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The Neuroscience of Behavior: Five Famous Cases

Five patients who shaped our understanding of behavior and the brain..

Posted January 16, 2020 | Reviewed by Lybi Ma

“Considering everything, it seems we are dealing here with a special illness… There are certainly more psychiatric illnesses than are listed in our textbooks.” —Alois Alzheimer (In: Benjamin, 2018)

Once thought to be the product of demonic possession, immorality, or imbalanced humors, we now know that psychiatric symptoms are often caused by changes in the brain. Read on to learn about the people who helped us understand the brain as the driving force behind our behaviors.

Phineas Gage

In 1848, John Harlow first described the case of a 25-year-old railroad foreman named Phineas Gage. Gage was a "temperate" man: hardworking, polite, and well-liked by all those around him. One day, Gage was struck through the skull by an iron rod launched in an accidental explosion. The rod traveled through the prefrontal cortex of his brain. Remarkably, he survived with no deficits in his motor function or memory . However, his family and friends noticed major changes in his personality . He became impatient, unreliable, vulgar, and was even described as developing the "animal passions of a strong man." This was the first glimpse into the important role of the prefrontal cortex in personality and social behavior (David, 2009; Thiebaut de Schotten, 2015; Benjamin, 2018).

Louis Victor Leborgne

Pierre Broca first published the case of 50-year-old Louis Victor Leborgne in 1861. Despite normal intelligence , Leborgne inexplicably lost the ability to speak. His nickname was Tan, after this became the only word he ever uttered. He was otherwise unaffected and seemed to follow directions and understand others without difficulty. After he died, Broca examined his brain, finding an abnormal area of brain tissue only in the left anterior frontal lobe. This suggested that the left and right sides of the brain were not always symmetric in their functions, as previously thought. Broca later went on to describe several other similar cases, cementing the role of the left anterior frontal lobe (now called Broca’s area) as a crucial region for producing (but not understanding) language (Dronkers, 2007; David, 2009; Thiebaut de Schotten, 2015).

Auguste Deter

Psychiatrist and neuropathologist Aloysius Alzheimer described the case of Auguste Deter, a 56-year-old woman who passed away in 1906 after she developed strange behaviors, hallucinations, and memory loss. When Alzheimer looked at her brain under the microscope, he described amyloid plaques and neurofibrillary tangles that we now know are a hallmark of the disease that bears his name. This significant discovery was the first time that a biological molecule such as a protein was linked to a psychiatric illness (Shorter, 1997; David, 2009; Kalia & Costa e Silva, 2015).

In 1933, Spafford Ackerly described the case of "JP” who, beginning at a very young age, would do crude things like defecate on others' belongings, expose himself, and masturbate in front of other children at school. These behaviors worsened as he aged, leading to his arrest as a teenager . He was examined by Ackerly who found that the boy had a large cyst, likely present from birth, that caused severe damage to his prefrontal cortices. Like the case of Phineas Gage, JP helped us understand the crucial role that the prefrontal cortex plays in judgment, decision-making , social behaviors, and personality (Benjamin, 2018).

HM (Henry Gustav Molaison)

William Scoville first described the case of HM, a 29-year-old man whom he had treated two years earlier with an experimental surgery to remove his medial temporal lobes (including the hippocampus and amygdala on both sides). The hope was that the surgery would control his severe epilepsy, and it did seem to help. But with that improvement came a very unexpected side effect: HM completely lost the ability to form certain kinds of new memories. While he was still able to form new implicit or procedural memories (like tying shoes or playing the piano), he was no longer able to form new semantic or declarative memories (like someone’s name or major life events). This taught us that memories were localized to a specific brain region, not distributed throughout the whole brain as previously thought (David, 2009; Thiebaut de Schotten, 2015; Benjamin, 2018).

Facebook /LinkedIn image: Gorodenkoff/Shutterstock

Benjamin, S., MacGillivray, L., Schildkrout, B., Cohen-Oram, A., Lauterbach, M.D., & Levin, L.L. (2018). Six landmark case reports essential for neuropsychiatric literacy. J Neuropsychiatry Clin Neurosci, 30 , 279-290.

Shorter, E., (1997). A history of psychiatry: From the era of the asylum to the age of Prozac. New York: John Wiley & Sons, Inc.

Thiebaut de Schotten, M., Dell'Acqua, F., Ratiu, P. Leslie, A., Howells, H., Cabanis, E., Iba-Zizen, M.T., Plaisant, O., Simmons, A, Dronkers, N.F., Corkin, S., & Catani, M. (2015). From Phineas Gage and Monsieur Leborgne to H.M.: Revisiting disconnection syndromes. Cerebral Cortex, 25 , 4812-4827.

David, A.S., Fleminger, S., Kopelman, M.D., Lovestone, S., & Mellers, J. (2009). Lishman's organic psychiatry: A textbook of neuropsychiatry. Hoboken, NJ: Wiley-Blackwell.

Kalia, M., & Costa e Silva, J. (2015). Biomarkers of psychiatric diseases: Current status and future prospects. Metabolism, 64, S11-S15.

Dronkers, N.F., Plaisant, O., Iba-Zizen, M.T., & Cabanis, E.A. (2007). Paul Broca's historic cases: High resolution MR Imaging of the brains of Leborgne and Lelong. Brain , 130, 1432–1441.

Scoville, W.B., & Milner, B. (1957). Loss of recent memory after bilateral hippocampal lesions. J. Neurol. Neurosurg. Psychiat., 20, 11-21.

Melissa Shepard, MD , is an assistant professor of psychiatry at the Johns Hopkins School of Medicine.

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Article Contents

Introduction, conflict of interest, acknowledgments.

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Case Report: A Comprehensive Neuropsychological Assessment of a Case of Superficial Siderosis

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Jodie R. Gawryluk, Lesley J. Ritchie, George Sicz, Andrea R. Kilgour, Brian J. Schmidt, Case Report: A Comprehensive Neuropsychological Assessment of a Case of Superficial Siderosis, Archives of Clinical Neuropsychology , Volume 32, Issue 4, June 2017, Pages 483–490, https://doi.org/10.1093/arclin/acx012

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Superficial siderosis (SS) is a neurodegenerative condition due to the long-term effects of hemosiderin deposition on the surface of the brain, cerebellum, brainstem, and spinal cord. SS symptoms include sensorineural hearing loss, ataxia and upper motor neuron signs. SS was diagnostically evasive until magnetic resonance imaging (MRI) became available. As the detection of SS improved, case studies have become more prevalent. To our knowledge, however, this is the first report of SS detailing a comprehensive neuropsychological assessment.

The current study presents a right-handed female in her early 60s, with a university level of education, who was diagnosed with SS.

Her neuropsychological profile showed impairment across multiple domains, including memory and executive function, with consistent behavioral findings. The results from a comprehensive neuropsychological assessment include dementia and a cerebellar cognitive affective syndrome.

Neuropsychological evaluation of a patient with new cognitive impairment in combination with unexplained hearing loss, gait disorder, or myelopathy should lead to a referral for MRI that includes techniques sensitive for iron deposition, in order to rule out SS.

Superficial siderosis (SS) is a disorder of the central nervous system (CNS) caused by chronic or intermittent bleeding into the subarachnoid space, typically at the level of the spine ( Kumar, 2010 ). Thirty-five percent of cases are idiopathic, 21% are caused by a CNS tumor or tumor resection, 13% result from identifiable head or spine trauma and the remaining 31% of cases are caused by a variety of conditions that are associated with subarachnoid hemorrhage ( Levy, Turtzo & Llinas, 2007 ). In each case, blood accumulates in the cerebrospinal fluid, where it breaks down into hemosiderin, which deposits on the surface of the CNS. The regions most vulnerable to hemosiderin deposition are those with the greatest exposure to blood-containing cerebrospinal fluid including the superior vermis, crest of the cerebellar folia, basal frontal lobe, temporal cortex, brainstem, spinal cord, nerve roots, and cranial nerves I and VIII ( Moreira et al., 2011 ). The deposition of hemosiderin in these locations results in gliosis, neuronal loss and demyelination ( Fearnley, Stevens, & Rudge, 1995 ).

Although SS was initially described over a century ago ( Hamill, 1908 ), the diagnosis can now be readily made pre-mortem using magnetic resonance imaging (MRI; Levy et al., 2007 ). Particular MRI acquisition methods, such as gradient echo T2- and T2*-weighted images, have a high sensitivity for hemosiderin deposition; therefore the accuracy and sensitivity of diagnosis has dramatically improved ( Kumar, 2010 ; Levy et al., 2007 ; Yamamoto, Yamamoto, & Kuroki, 2012 ). If a dural tear is detected as the presumed cause of chronic hemorrhage and SS, then it can be sealed through surgical intervention ( Egawa et al., 2013 ; Lekgabe & Kavar, 2012 ; Shih, Yang, Batjer & Liu, 2009 ). A recent case report described clinical and MRI improvement in a man with SS treated with the lipid-soluble iron-binding agent, deferiprone ( Levy et al., 2007 ).

Patients with SS typically have progressive neurological sequelae ( Fearnley et al., 1995 ). The disease can remain latent, from the time of initial bleeding to the development of symptoms, from 4 months up to 30 years ( Moreira et al., 2011 ). The most common symptoms include a triad of sensorineural hearing loss (95%), cerebellar ataxia (88%), and myelopathy (76%; Fearnley et al., 1995 ; Levy et al., 2007 ). Importantly, a symptom described in early reports of SS, but only rarely the focus of discussion in the literature, is cognitive decline (e.g., Cheng, Chen, Wang, & Lin, 2011 ; Stevens, Petersen, Grodd, Poremba, & Dichgans, 1991 ; Tomlinson & Walton, 1964 ). To date, there exist only a few reports of the neuropsychological profile of SS and most of these are based on an abbreviated battery of assessment measures.

One of the first, and largest, reports on neuropsychological aspects of SS was by van Harskamp, Rudge, and Cipolotti (2005) , who documented cognitive, social, and emotional processing in six patients with SS. Their neuropsychological assessment battery included the Wechsler Adult Intelligence Scale, the National Adult Reading Test, Recognition Memory Tests (for words and faces), the Rey Osterrieth Complex Figure Test, Trails A and B, Hayling Sentence Completion, and a modified Wisconsin Card Sorting Test. They found that general intellectual functioning was preserved, as was speed of information processing. In contrast, they found significant impairments in speech production, visual recall, and executive functioning. SS patients were also noted to have difficulty on a measure of theory of mind.

In 2009, Uttner and colleagues presented a 65-year-old female with SS. They observed severe deterioration of verbal and nonverbal memory, information processing speed and verbal fluency as measured by the Corsi-Block Span, Digit Span, and a 16-item Verbal Learning Test, the Doors Test, Stroop Test, and the Controlled Oral Word Association Test.

Le Scanff, Vighetto, Gedeon, Bonnefoy, and Krolak-Salmon (2009) described two patients who presented with dementia as the primary manifestation of SS. The authors did not detail the neuropsychological test battery employed, but did note that standardized neuropsychological evaluations revealed impaired attention, executive functioning, and visuocontructive skills. The authors concluded that dementia could be a sign of SS, which can be accurately diagnosed via neuroimaging.

Most recently, Dubessy and colleagues (2012) described a 75-year-old man with a Mini Mental State Examination score of 16 (with impaired language, praxis and executive functions). The authors estimated that the findings of dementia were secondary to SS and concluded that dementia is “probably underdiagnosed” in this group.

There is limited information regarding the neuropsychological profile of SS. Existing case studies have utilized a narrow neuropsychological test battery with mixed findings, which made a priori hypotheses difficult. To the best of our knowledge, the present study provides the most comprehensive assessment to date.

The patient and her family both provided informed consent for publication of the following case. The current study was also approved by the local Research Ethics Board.

Diagnosis of Superficial Siderosis and Initial Symptoms

Magnetic resonance imaging (MRI) showing hemosiderin deposition. The arrows show areas of typical confluent T2 signal hypointensity, indicative of hemosiderin deposition, present over the surface of medulla and cerebellar folia (A), medial temporal lobes and midbrain (B), and Sylvian fissure and dorsal aspect of the thalami (C). A mid-sagittal T1 FLAIR image shows atrophy of the cerebellum and brainstem (D).

Initial studies failed to identify a source of bleeding. She was subsequently referred to a tertiary care facility and underwent a series of spinal neuroimaging studies, which demonstrated a dural tear and cerebrospinal fluid leak at the C7-T1 level. The cerebrospinal fluid contained red blood cells and bilirubin. It was concluded she might have been bleeding, either continuously or intermittently, for over 30 years.

During the 4 years of observation, following initial development of hearing loss and impaired balance, these symptoms progressed and she developed bilateral nystagmus, impaired fine motor coordination and dysarthria. Along with the development of these secondary symptoms, she also reported memory difficulty at the time of diagnosis, which was progressive. She was referred for neuropsychological assessment with a diagnosis of SS (without any comorbid diagnoses) to determine her level of cognitive function and ability to function independently.

An intake interview and collateral interview were completed to gather information regarding the patient's level of functioning. Given that the literature to date did not include a comprehensive neuropsychological assessment of a case of SS, a comprehensive battery was chosen that would capture the domains of intellectual functioning, attention and processing speed, language, memory, executive functioning, visual spatial skills, and motor-sensory skills. Measures of personality and mood were also administered to allow for interpretation of the test scores with the context of emotional well-being. As per routine, measures of test engagement or effort were administered at different points in time during two testing sessions.

Neuropsychological Assessment

Subjective cognitive symptoms.

The patient had been experiencing memory difficulties for 2 years. She required more time to complete routine tasks and often needed to re-check her performance. She also reported imbalance and hearing loss. She denied concerns regarding her mood.

The patient permitted interviews with significant others. The collateral information was considerably disparate from the patient's self-report. In particular, collateral information suggested substantial decline in the patient's short-term and prospective memory. For example, the patient was noted to forget whether she had eaten, which seemed to correlate with recent unintentional weight loss. Dependence for all activities of daily living (e.g., financial management, medical management, self-care, and meal preparation) was also noted. Collateral report revealed that, due to functional deficits, she had been residing with a family member for 2 months, a fact that she was unable to recall during the intake session. Concern regarding her progressive balance deterioration and risk for falls was reported. Collateral history did not raise concerns about her mood, although intermittent irritability was acknowledged. She was noted to quickly forget reasons for her distress and return to her baseline positive mood and affect.

Patient Presentation

The patient ambulated with the aid of a walker and her gait was unsteady. No evidence of tremor or nystagmus was identified. Despite reported hearing loss on the left side, she was able to communicate effectively and respond to questions. Repetition of test instructions was required to accommodate memory and speech deficits. Her speech was fluent and void of word-finding deficits.

The patient's presentation included multiple behavioral indicators of executive dysfunction. For example, she exhibited an impulsive approach to testing and spoke uninhibitedly about personal relationships. She presented as younger than her biological age, with interactions that were overly familiar and casual, immature language. Her behavior was incongruent with the social situation. For example, she requested utensils from a passerby while sitting in the waiting room of the treatment office and made frequent requests for food and beverages during the testing session. Marked perseverative tendencies, limited insight, and social disinhibition were noted. Disorientation (e.g., to location of her purse and walker) appeared related to profound memory deficits. The patient did not meet the criteria for delirium. She was attentive during the intake and evaluation and no alterations in level of arousal were noted. No evidence of hallucinations or delusions was identified. Consistent with collateral report, bouts of irritability were short-lived. In general, she was cooperative, pleasant, and able to communicate effectively. Good rapport was easily established and maintained.

Comprehensive Test Battery

Comprehensive neuropsychological assessment results organized by domain of function

Psychometric Test Results

Table 1 shows her scores for the individual tasks.

Review of the scores presented in Table 1 , reveals variable performance on measures of engagement in testing. Notably, many engagement measures administered to this patient are based on a forced-choice recognition paradigm. While the patient did not meet the standard for valid responding on some of these tests, she did not perform at a chance or below-chance level.

Her performance was deemed to reflect the severity of her memory deficit, rather than poor effort during the assessment.

Her neuropsychological profile shows impairment across multiple domains. In particular, her performance on indices of perceptual reasoning and processing speed fell below her estimated level of premorbid function and was suggestive of a decline in intellectual functioning. In terms of processing speed, her accuracy was greater than her speed. She was not oriented to place (e.g., stating that she was at someone's home rather than the hospital) or time (e.g., stating that it was July rather than November). Impaired memory for both visuospatial and auditory information was noted. On administration of the California Verbal Learning Test – II, the patient demonstrated an encoding deficit and presented with a blank look when asked to recall items, noting, “the first list got erased.” On the Rey Complex Figure Test, the patient recalled a circle with three dots, which was reproduced on recall as a face with two eyes and a nose. Evidence of executive dysfunction included impaired deductive reasoning and perseveration. Her performance on executive tasks was highly consistent with her behavioral presentation. Qualitatively, she was perseverative in her speech, impulsive, and demonstrated impaired insight regarding her behavior and cognitive functioning. Her performance also fell in the borderline or impaired range on measures of processing speed, visual reproduction, confrontation naming, semantic fluency, and speeded manual dexterity. In particular, speeded manual dexterity (Grooved Pegboard) was impaired, bilaterally and the task was discontinued for her left hand after 5 min as a result of her slow speed. She demonstrated impulsivity on the grooved pegboard task, as she began reaching for the pegs prior to being given instructions. She had difficulty grasping the task instructions and required reminding to use only one hand at a time. When attempting the task with one hand, she used the table or her chest to assist her. She did not recognize that all of the pegs were the same and frequently picked one up and then exchanged it for another commenting that “this one doesn't fit” or “it's too big.” In terms of other specific observations, during administration of the Boston Naming Test, the patient either described the item (e.g., said what the item was used for) or provided a semantically related response (e.g., naming the incorrect animal); phonemic cues did not significantly improve recall. Markedly, on administration of the Trail Making Test A, the patient became stuck at one point, which increased her time to completion and may explain her lower performance relative to part B of the test. Of note, ideomotor apraxia and hearing difficulties were not deemed to have a significant affect on the patient's presentation or neuropsychological profile; rather, slow processing speed, memory deficits, and profound executive dysfunction, were identified as the most prominent areas of compromise.

Despite the aforementioned areas of compromise, no evidence of significant impairment in working memory, visual construction, and expressive vocabulary was identified. Performance in these areas fell well within normal limits. Consistent with her self-report, she endorsed normal levels of depression and anxiety.

Case Summary

This report describes a woman in her early 60s with a history of SS and memory impairment. A neuropsychological evaluation was requested to assess her current level of cognitive functioning and formulate recommendations for supervision.

Case Conclusions

Overall, the patient's behavioral presentation and neuropsychological profile were considerably more compromised than expected, given the existing literature on SS. This was clearly evident by the patient's lack of insight regarding her living situation at the time of the assessment. Given her dependence for activities of daily living (e.g., cooking, bathing, managing medications and finances), decline in general intellectual function, and multiple areas of neuropsychological decline (e.g., impaired memory, confrontation naming, executive functioning), she was deemed to meet the criteria for a diagnosis of dementia. Recommendations for 24-hr supervision and assistance with decision-making (i.e., medical and financial) were provided. General cognitive strategies, such as maintaining a structured routine and keeping written notes of important tasks, were discussed at feedback. Subsequent to her neuropsychological assessment, the dural leak was surgically repaired.

Case in the Context of the Literature

The current case study on SS documents the results of a comprehensive neuropsychological examination. Although some aspects of the patient's cognitive profile remained within normal limits, the areas in which she scored below expected levels are largely consistent with the available literature. In particular, findings of impaired visual and verbal memory are consistent with the findings of Uttner, Tumani, von Arnim, and Brettschneider (2009) and van Harskamp and colleagues (2005) . Decreased perceptual reasoning, attention and processing speed are consistent with observations by Le Scanff and colleagues (2009) and Uttner et al. (2009) , whereas poor language and motor skills support the report by Dubessy et al. Executive dysfunction is the most commonly identified cognitive impairment described in the SS literature ( Dubessy et al., 2012 ; Le Scanff et al., 2009 ; van Harskamp et al., 2005 ; Uttner et al., 2009 ). While our patient exhibited compromised deductive reasoning, the most prominent evidence of executive dysfunction was noted in her behavior. In particular, she exhibited markedly compromised insight, interpersonal skills, and situational skills, as well as strong perseverative tendencies, impulsivity, and disorganization. Although the patient did not exhibit attention difficulties, our findings remain highly consistent with others, who have proposed cerebellar cognitive affective syndrome as a possible explanation for cognitive symptoms in SS ( Uttner et al., 2009 ; van Harskamp et al., 2005 ).

Cerebellar cognitive affective syndrome was first described by Schmahmann and Sherman (1998) , who performed neuropsychological assessments on 20 patients with localized cerebellar damage. They identified marked changes in behavior as the most prominent presenting features in a subset of patients with cerebellar damage involving the posterior lobe and vermis. Their results revealed impairment in executive functioning (i.e., planning, set-shifting, verbal fluency, abstract reasoning, and working memory), including personality change with disinhibited and inappropriate behavior. Additionally, visuospatial organization, memory, and language impairments were observed in this group. The authors suggested that these deficits result from disruption of the cerebellar modulation of neural circuits that link prefrontal, posterior parietal, superior temporal and limbic cortices with the cerebellum. Since the original formulation of cerebellar cognitive affective syndrome, other articles have lent support to the idea that the cerebellum is involved in cognitive and affective functions (e.g., Baillieux et al., 2010 ; Baillieux, De Smet, Paquier, De Deyn & Mariën, 2008 ; Gordon, 2007 ; Tavano & Borgatti, 2010 ). The behavioral and cognitive deficits reported in patients with SS are consistent with the cerebellar pathway damage observed in cerebellar cognitive affective syndrome. The patient described in the current study did not demonstrate some of the common deficits associated with cerebellar cognitive affective syndrome. In the current case, it is likely that partial cerebellar affective syndrome plus involvement of other cortical and subcortical regions may be present (e.g., the radiology report noted hemosiderin deposits in the medial temporal lobes and midbrain). In particular, given the domains of intact performance (e.g., passive attention) in combination with the MRI findings suggest that posterior frontal and parietal regions are relatively spared compared to prefrontal–striatal–cerebellar and temporal–striatal–cerebellar connections.

In the current case study, given that the patient presented with significant impairment in multiple domains of cognitive function, as well as an observable decline in function noted by collateral informants and difficulties performing activities of daily living that could not be otherwise explained, she was diagnosed with dementia. The findings in the current case are congruent with an early review by Fearnley and collagues (1995), which reported an association between SS and dementia in up to 24% of SS cases. Comorbidity of SS and dementia is also consistent with previous case studies ( Dubessy et al., 2012 ; Le Scanff et al., 2009 ). Additionally, Zonneveld et al. (2014) , reported that 2.1% of patients in a memory clinic setting met the diagnostic criteria for SS. Whether dementia is a consequence of the advanced stages of SS is yet to be determined. Our patient developed symptoms of hearing loss and imbalance 10 years before neuropsychological assessment and was thought to have likely suffered the onset of chronic cerebrospinal fluid hemorrhage 30 years earlier. Further research evaluating the risk factors for the development of dementia in patients with SS is required.

None declared.

The authors would sincerely like to thank the patient and her family. We are also grateful to Dr. John Arnett in the Clinical Health Psychology Department at Winnipeg Health Sciences Centre for his helpful suggestions.

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• hemosiderin
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• spinal cord diseases
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• iron deposition
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• cerebellar cognitive affective syndrome
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Six Landmark Case Reports Essential for Neuropsychiatric Literacy

Information & authors, metrics & citations, view options, phineas gage.

It is due to science, that a case so grave, and succeeded by such remarkable results, should not be lost sight of; that its subsequent history, termination, and pathological evidences, in detail, should have a permanent record. —John M. Harlow 1

Louis Victor Leborgne (“Tan”)

We speak with the left hemisphere. —Pierre Paul Broca 9

Auguste Deter

Considering everything, it seems we are dealing here with a special illness…. There are certainly more psychiatric illnesses than are listed in our textbooks. —Alois Alzheimer 20

Solomon Shereshevsky (S)

[I]t appeared that there was no limit either to the capacity of S.’s memory or to the durability of the traces he retained . —Alexander Luria 31

Each morning the editor would meet with the staff and hand out assignments for the day.... The list of addresses and instructions was usually fairly long, and the editor noted with some surprise that S. never took notes. He was about to reproach the reporter for being inattentive when, at his urging, S. repeated the entire assignment word for word. 31

[M]an cannot elaborate his social sense so that it can become part of his total self without “the great nerve net” of his frontal lobes. —Spafford Ackerly and Arthur Benton 33

He never holds a grudge nor speaks ill of anyone, never picks a fight, never tricks anyone….One is struck with the childish simplicity and superficiality of his petty lying and stealing and sex experiences which are unpremeditated. Yet these acts are never the result of pure impulse dissociated from their settings. Of all patients encountered he is by far the most stimulus bound….Everybody knows there is something radically wrong, but no one can put his finger on it. 35

Henry Gustav Molaison (HM)

Henry Gustav Molaison... left no survivors. He left a legacy in science that cannot be erased. —B.H.M. Carey 40

Acknowledgments

Information, published in.

• Diagnosis and Classification in Neuropsychiatry
• Childhood Neuropsychiatric Disorders
• Cognitive Disorders
• Rehabilitation (Neuropsychiatric)
• Neuropsychiatric Education

Competing Interests

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Single case-control design for the study of the neuropsychological deficits and dissociations in Huntington’s disease-like 2

Aline ferreira-correia.

a University of the Witwatersrand, Department of Psychology, School of Human and Community Development, Johannesburg, South Africa

David G. Anderson

b University of the Witwatersrand Donald Gordon Medical Centre, Neurology, Johannesburg, South Africa

c Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

Kate Cockcroft

Amanda krause, associated data, graphical abstract.

The Single-Case Methodology in Neuropsychology (Crawford & Howell, 1998) is a research design and robust inferential statistical method that facilitates the neuropsychological description of one case in terms of the differences between its profile and the performance of a carefully matched sample (Crawford & Garthwaite, 2012). The comparison is made by means of a t -test statistic that treats the normative sample as a sample and not as a population, with a particular effect-size associated with the size (n) of the sample. It is an ideal method for the neuropsychological investigation of rare diseases, such as Huntington’s Disease Like-2 (HDL2), especially when the cases are embedded in contexts of great diversity. This paper presents a step by step guide to the implementation of this method in a series of demographically and clinically diverse group of patients.

• • The application of a Single-Case Methodology in Neuropsychology enables the characterisation of rare diseases while controlling for demographic and context-related variables.
• • The implementation Single-Case Methodology in Neuropsychology provides test norms for homogenous groups that can be used by practitioners in their clinical work.
• • The method was customised for the South African population by controlling variables of specific relevance, such as linguistic diversity and quality of education.

Specification Table

Method details

Step 1: assessment of the suitability of the method, identification of rare cases.

The Single-Case Methodology in Neuropsychology [ 1 ] is a research design and robust inferential statistical method that facilitates the neuropsychological description of one case in terms of the differences between its profile and the performance of a carefully matched sample of modest size [ 2 ]. Thus, it is ideal to implement for rare or unique cases or when the establishment of clinical groups is not possible due to the heterogeneity of the cases in terms of relevant clinical variables (e.g. disease progression, age of onset, and severity of the genetic mutation).

Huntington Disease Like-2 (HDL2) is an autosomal dominant genetic disease caused by mutations that produce a pathogenic expansion of a triplet repeat in chromosome 16q24.3 in a variably spliced exon of junctophilin-3 (JPH3). It is the phenocopy that most resembles the clinical presentation of Huntington’s Disease (HD). Huntington’s Disease Like-2 is very rare [ 3 , 4 ], with a strong ethnic implication as most, if not all, of the individuals with HDL2 have predominantly African ancestry [ 51 ](Rudnicki & Margolis, 2008). Consequently, no group studies on the characterisation of HDL2 are available.

Identification of context-relevant variables

This method performs a comparison between the case’s scores and the mean of the matched control group. This comparison is made by means of a t -test statistic that treats the normative sample as a sample and not as a population (unlike z scores), with a particular effect-size associated with the size ( n) of the sample. A premise of the single-case study methodology is that the matched control sample potentially represents the premorbid functioning of the clinical case, thus, it is important to identify relevant contextual variables that act as a moderators of cognitive performance. Specifically, the selection of a matched control sample permits the investigation of neurocognitive performance while indirectly controlling for covariates [ 1 , [5] , [6] , [7] , [8] ], such as age, level of education [ [9] , [10] , [11] ], quality of education [ 12 ], and ethnicity (in terms of linguistic practices and historical disadvantages attached to ethnicity) [ 13 , 14 ], which have a significant impact on cognitive testing.

In South Africa, neuropsychological assessment faces great challenges linked to the history of apartheid which resulted in significant socioeconomic inequalities and variances of educational opportunities associated to ethnicity [ 15 ], as well as vast linguistic and cultural diversity [ 16 ]. These factors are associated with wide performance differences between standardised tests scores of different samples, especially when South Africans are compared against foreign norms [ 17 ]. The most affected by this bias are those South Africans from rural areas and/or who attended disadvantaged schools [ 18 , 19 ]. Therefore, the selection of matched control samples was conducted in order to control for the following context-relevant variables: age, level of education, type of school (public/government only), English second language speakers (polyglot participants only), and race. All participants in the study self-identified as belonging to two racial groups that have a history of socioeconomic disadvantage in South Africa (Black and Mixed race 1 ).

Other variables, such as developmental history [ 21 , 22 ], gender [ 10 ], current pharmacological treatment [ 23 ], socioeconomic status [ 24 ], medical factors linked to HD/HDL2 (such as repeat length and age of onset) [ 25 ], acculturation [ 12 ], fatigue [ 26 ], mood [ 27 , 28 ], motivation [ 29 ], testing environment [ 26 ], and test wiseness [ 30 ], are moderators, to different degrees, of test performance. While these variables could not be strictly controlled, it is anticipated that their effects were mitigated by matching the controls and the HD patients to the HDL2 patients. Nevertheless, the possibility of their effect on the performance on the test must be borne in mind. Participants with medical histories with a known impact on cognition, such as HIV, metabolic and other neurological conditions (e.g. traumatic brain injury), were excluded from the sample.

Sampling considerations

A total population sampling method [ 31 ] was implemented for the recruitment of the HDL2 cases whereas a purposive homogenous sampling [ 31 ] was used for the configuration of the healthy control groups. The healthy participants were matched to the clinical cases in terms of age, years of education, type of schooling (only public, primary and secondary schools were included), and ethnicity. The healthy controls did not have a history of genetic disease, or any reported motor, psychiatric or cognitive symptoms. Only participants who were able to converse in English were included from the clinical and healthy sample, while those participants with other comorbid neurological or metabolic diseases, a history of traumatic brain injury with loss of consciousness, abuse of illegal drugs, and/or who did not give formal consent, were excluded from participation.

The research design and the statistical method linked to it is suitable even for very small control samples (n = 5), nevertheless, predictive power is associated with the size of the control sample, with bigger samples possessing greater power to detect differences and effects [ 1 , 8 ]. A sample of at least 20 controls was the minimum required to reject the null hypothesis and to reduce the rate of type I error [ 32 ]. Therefore, the size of the control groups met the criterion of n ≥20.

Step 2: Establishment of the assessment protocol

Since the purpose of the research was to establish a cognitive profile of HDL2 (deficits and dissociations), measurements of a wide array of constructs in both visual and verbal domains were included. Subsequently, test selection was guided by three aspects: the identification of instruments frequently used in the Huntington’s Disease (HD) literature (given the similarities between HDL2 and HD), availability of the instruments and the time constraints imposed by the study design. Given that participation in the study involved other activities besides the neurocognitive assessment, only two hours were available for the evaluation of each patient, so preference was given to brief tests. All the instruments used are described below.

The Demographic questionnaire assessed variables such as: age, level of education, occupation, language experience (language spoken in order of self-assessed proficiency and languages used daily), gender, ancestry, HDL2 history (diagnosis, onset and symptomatology), general medical history and medication.

The Montreal Cognitive Assessment (MoCA) [ 33 ] is a neuropsychological screening test for identifying cognitive impairment. It assesses a variety of cognitive functions, including attention and concentration, executive functions, memory, language, visuoconstructive abilities, abstract thinking, arithmetic ability and orientation in approximate 10 min [ 33 ]. The English 7.1 version was used (Lion, Rhinoceros, Camel, Version). The total score was calculated including the additional point awarded to the participants with less than 12 years of education.

The Rey Auditory Verbal Learning Test (RAVLT) [ 34 ] assessed verbal attention and concentration span under overloaded conditions [ 26 ], and evaluates verbal memory (immediate, delay and recognition). It takes approximately 20 min to be administered and the lists A–B were used.

The Stroop Word-Colour Interference Test (SWCIT) [ 35 ] measures concentration (selective attention) and executive function (cognitive flexibility and inhibition) [ 35 ]. This test consists of three pages with 100 items (of words Red, Green and Blue) each organised in five columns of 20 items; the first page (Word Reading) presents only the words in black ink organised randomly, the second page (Colour Naming) consists of the symbols XXXX printed in either of the three inks and, on the fourth page (Colour-Word Reading), pages one and two are combined, having a word printed in a different colour than the name suggests [ 35 ]. The participant has only 45 s for each trial, hence the test takes approximately 5 min to administer.

Two subtests from the Wechsler Adult Intelligence Scale-IV (WAIS-IV) were selected, including the Symbol Search Subtest [ 36 ], which evaluates visual attention in terms of information processing speed and visual perception [ 36 ]. In this subtest, the examinee must mark ‘yes’ or ‘no’ if one of the target symbols is found in a group of symbols. The participant should correctly identify as many items as possible within 120 s [ 36 ]. The Letter-Number Sequencing Subtest [ 36 ] assesses verbal working memory. Here, the participant must rearrange a combination of numbers and letters that are presented to them orally. It consists of 7 items with 3 trials each and the test has a duration of 10 min approximately.

From the Wechsler Memory Scale-IV (WMS-IV) two subtests were included in the assessment battery. Firstly, the Spatial Addition Sub-Test [ 37 ] asseses visual working memory by asking the participants to solve a problem of visual addition presented in a sequence of grids and following a set of rules [ 37 ]. Secondly, the Visual Reproduction I and II Subtests [ 37 ] evaluate immediate (I) and delayed (II) non-verbal memory. For Visual Reproduction I, the participant must draw a design from memory after viewing it for 10 s. For Visual Reproduction II, the participant must draw the same designs from the first trial after a period of interference and is also required to choose from six designs those that matched the original ones (immediate recall).

The Controlled Oral-Word Association Test (COWAT) [ 38 ] is a measure of verbal fluency, which consists of three naming trials (frequently the letters F, A and S [ 26 ]. The participant is asked to say as many words as possible starting with each letter, for one minute per trial [ 38 ].

Two subtests were selected from the Delis-Kaplan Executive Function System (D-KEFS). Firstly, the Design Fluency Test [ 39 ], which consists of an unstructured activity in which the participant is required to produce, in three trials of 60 s each, as many different designs as possible, by connecting dots in a grid using a pencil. It assesses non-verbal fluency, cognitive flexibility and response inhibition [ 39 ]. Secondly, the Tower Test [ 39 ] was selected from the D-KEFS. The purpose of the task is to build a designated or target tower in the fewest number of movements possible using discs varying in sizes (small to large), following two rules: move only one disc at a time and never place a larger disc over a smaller disc [ 39 ].

The Symbol Digit Modalities Test (SDMT) [ 40 ] assesses divided attention, visual scanning, tracking and motor speed [ 41 ]. It consists of a substitution task where the participant has to pair numbers with geometric symbols for 90 s [ 40 ], which is done in writing for the first form, and orally in the second form.

The Hooper Visual Organization Test (HVOT) [ 42 ] measures visual organization ability. It consists of 30 pictures of cut up objects that have been rearranged and the examinee has to recognise and name each [ 26 ].

Lastly, the Purdue Grooved Pegboard Test (PGPT) [ 43 ] assesses manual dexterity [ 26 ]. The objective of the task is to place pegs, one by one, as quickly as possible, in a row of holes, using firstly the dominant hand and, in the second trial, the non-dominant hand [ 41 ].

The Magnetic Resonance Imaging (MRI) conducted on the HDL2 patients was done at the University of the Witwatersrand Donald Gordon Medical Centre Radiology Department on a 1.5 T Philips Intera MR scanner (Philips Medical Systems, Eindhoven).

All clinical participants met with an independent genetic counsellor who provided detailed information about the study and obtained formal written consent. The consent from the healthy participants was obtained directly by the assessor. The implementation of the research protocol after consent included, first, the neurological assessment, which culminated with the procurement of a blood sample. Second, the participant undertook the neuropsychological assessment. Third, the participant was transported to the MRI facilities, where lunch was provided upon arrival. Variations of this typical protocol were sometimes necessary in order to accommodate for special circumstances such as refusal or inability to take part in certain aspects of the study (e.g. MRI or neuropsychological assessment).

The order of administration was as follows: 1) Demographic questionnaire, 2) MoCA, 3) RAVLT (trials I to V, trial B, trial VI), 4) Design Fluency Sub-Test, 5) SDMT, 6) HVOT, 7) Spatial Addition Sub-Test, 8) RAVLT Delayed trial and Recognition Trial, 9) Visual Reproduction I Sub-Test, 10) Letter-Number Sequencing Sub-Test, 11) Symbol Search Sub-Test, 12) COWAT, 13) Tower Sub-Test, 14) SWCIT, 15), Visual Reproduction II Sub-Test, and 16) PPT. Behavioral and clinical notes were kept across the entire assessment. Variations on this protocol took place due to issues beyond the researchers’ control; nevertheless, the interruptions were managed in order to preserve the delay periods in the memory tests. Breaks were offered after the RAVLT recognition trial. All assessments were conducted in a well-lit and ventilated space, on a flat surface (table or desk) in a quiet room.

In order to establish the neuropsychological profile of HDL2, it was necessary to identify the pattern of multiple cognitive functions. Although no single test provides a pure measure of a particular function, for the purpose of facilitating the interpretation of the profile, specific tests or subtests have been grouped under the core cognitive domain that each test intends to assess. Thus, the specific core tests assessing each of the cognitive variables are specified in Table 1 .

Operational definition for each cognitive function to be assessed.

Step 3: Preliminary analyses

Normality assessment.

Crawford and Howell’s [ 1 ] t- Test requires the assumption of a normal distribution to be met. Therefore, the characteristics of the distribution were reviewed by means of visual inspections of data histograms for each control group separately, using SAS version 9.4 [ 44 ] (Supplementary Data File 1). For sample groups of 30 or fewer, the use of histograms is recommended to assess normality [ 45 ]. Most of the variables appeared to be normally distributed with slight variations in terms of kurtosis and skewness. However, this did not hold for extreme cases, which were found in the following tasks: RAVLT Recognition trial, and SDMT Speed and Accuracy Index; thus affecting the conditional distribution and increasing the possibility of Type I error. Ceiling effects are common in tasks that should be within the competence of healthy controls and in measurements of pathological deviations from the instruction (e.g. errors), which cause an extreme distribution that is skewed and most likely leptokurtic [ 32 ]. According to the argument and empirical evidence presented by Crawford et al. [ 32 ], this is highly problematic for smaller samples (n≤20) where the risk of Type I error increases considerably. Bearing in mind that all control samples in the current study comprised approximately 20 participants, the limitation of small samples may apply to this study. Yet, methods available to normalise the data are not applicable for single case control studies where the samples are too small to adjust, or when the characteristics of the test do not allow for such transformation given the limited range of scores [ 32 ]. Both conditions are applicable to the data from the control groups’ data in this research.

Nonetheless, Crawford et al. [ 32 ] still recommend that the method be used on the grounds of sustaining its power when the assumption of normality is not met [ 1 ], even under extreme conditions of kurtosis and skewed distributions [ 32 ]. In addition, t- scores are significantly less biased than z -scores and can provide a reliable measure of the probability of the score’s deviation from normality. In spite of its robustness, the authors warn about the increased risk of incorrectly judging a score as deficient due to an inflation of Type I error rate. Given these guidelines and the exploratory nature of the study, only the tasks with a standard deviation of zero (such as Number of Pegs achieved at five minutes in the PGPT) and those that were extremely skewed (such as Orientation of the MoCA) were excluded. Other tasks which displayed a non-normal distribution were not excluded from the analysis of deficit, these findings were interpreted cautiously and the associated risks and limitations of this decision are highlighted in the Discussion chapter.

Correlations

The modified t -test analysis [ 1 , 46 ] allows for the exploration of deficits while controlling for the effects of covariates, thus, correlational analyses were necessary. Age and level of education are the most important covariates of neuropsychological performance [ 7 ]. Although the controls were matched on these two variables, meaningful variations within the parameters (in a somewhat arbitrary manner) are possible. A third variable that correlates highly with cognitive performance is psychomotor speed [ 7 , 47 ]. Since this is a function severely affected in HDL2, it is important to determine if the deficit in an ‘unrelated' function was moderated by psychomotor speed. Three measures were considered specifically for the purpose of exploring potential psychomotor speed effects: PGPT time dominant, PGPT time non-dominant, and Symbol Search Correct. These were chosen because they displayed distributions that appeared normally distributed and are reliable measures of speed. As for age and years of education, if any of these covariates significantly correlated with the task under investigation, new analyses were conducted in order to control for their possible moderation effects. If more than one of the speed of processing tests correlated significantly with the task at hand, the one with the highest and most significant correlation was chosen for the analysis.

It is important to note that this method does not require a multivariate or bivariate normal distribution [ 7 ]. Therefore, a correlation matrix was carried out using SPSS version 9.4 for Windows [ 48 ] and it was conducted separately for each control group (Supplementary Data File 2). Specifically, this analysis consisted of pairwise correlations between variables, which were measured by Spearman’s correlation coefficient. The selection of Spearman’s correlation over Pearson’s is justified by the small sample size and the histograms, which do not show normal distributions for most variables.

Data selection

The initial analysis were conducted using 64 test variables, which included, for example, all the subtests of the MoCA and all the errors and times on the different tests. This number was reduced to 33 after implementing a “data reduction strategy” (Stout et al., 2012, p. 5) that involved selecting the tests or subcomponents thereof that are known to have the best psychometric properties, especially in terms of their sensitivity to measure the cognitive variable of interest. This was a necessary step as all the calculations are done manually and one by one.

Step 4: Analysis of deficits

The analysis of deficit was achieved by comparing the raw score 2 of the patient on each of the tests with the performance of the matched control group. The t -test developed by Crawford and Howell [ 1 ], based on Sokal and Rohlf’s method (1995, as cited in Crawford and Howell [ 1 ]), was the inferential statistical method used to explore the presence of deficits in all cases. This method tests whether the score obtained in a test is significantly below that of the control. A significant difference is therefore interpreted as deficit, thus, both of these terms indicate extremely low performance. The method was further updated by Crawford et al. [ 46 ], and the newer version provides additional data regarding the percentage of the control population that would obtain a score lower than the patient, as well as estimates of effect sizes.

The operational definitions provided by Crawford et al. [ 6 ] for interpreting a score are:

• - Within normal limits : the patient’s score on a given test is not significantly lower than that of controls using Crawford and Howell [ 1 ] and Crawford et al. [ 7 ] method and a one-tailed test (p < 0.05).
• - Deficit : the patient’s score on a given test is significantly lower than that of controls using Crawford and Howell [ 1 ] and Crawford et al. [ 7 ] method and a one-tailed test (p < 0.05).

The severity of deficit can be inferred from the size of the t -test in conjunction with the p -value. A large t -test would be indicative of a large distance between the case’s score and the control mean, which, if negative, would indicate a severe deficit, similarly to the interpretation of the z -score. Considerations regarding the distribution of the control group should be included in this reading of severity.

Following the modified t -test analysis [ 1 , 46 ], all significant deficits (p < 0.05) were further tested while controlling for the effects of covariates, in order to explore whether the dissociation remained when the effects of cofounding variables were removed.

For these two t- tests (with and without consideration of covariates), a one-tailed test was used because there is a clear direction towards lower performance by the HDL2 cases in comparison to controls in the alternate hypothesis [ 49 ]. The program Singlims_ES.exe ( Fig. 1 ) was used for the purpose of testing for deficits and dissociations [ 1 , 46 , 50 ], while the program BTD_Cov.exe ( Fig. 2 ) was used to test if dissociations remained significant in the presence of selected covariates [ 7 ]. For these two t- tests (with and without consideration of covariates), a one-tailed test was used because there is a clear direction towards lower performance by the HDL2 cases in comparison to controls in the alternate hypothesis [ 49 ]. The program Singlims_ES.exe was used for the purpose of testing for deficits and dissociations [ 1 , 46 , 50 ], while the program BTD_Cov.exe was used to test if dissociation remained significant in the presence of selected covariates [ 7 ]. The data is summarised in tables following the authors’ guidelines [ 46 ] ( Table 2 ).

Screen shot of the program Singlims_ES.exe.

The data requested must be introduced manually and the calculations are rendered immediately.

Screen shot of the program BTD_Cov.exe.

The data requested must be introduced manually and the calculations are rendered immediately. The correlation matrix between the covariates and the test under investigation is necessary. This matrix expands according to the number of covariates introduced.

Crawford et al. [ 46 ] guidelines on the presentation of the data for the identification of deficits with and without controlling for covariates.

n-1 degrees of freedom.

Step 5: Analysis of dissociations

The intra-case variability was explored in order to establish whether the pattern of performance in the tasks meets the criteria of classical or strong dissociation [ 46 , 49 ]. The Revised Standardized Difference Test (RSDT) was used for testing the difference between the patient’s scores in two tasks, which is subsequently compared to the distribution of standardised differences from the control sample [ 49 ]. The program Dissoc_ES.exe ( Fig. 3 ) was used and a two-tail analysis was selected because, although alternate hypotheses were available, they do not specify the exact direction in which the deficit will be displayed [ 49 ].

After comparing the HDL2 case to the control sample, it is possible to differentiate scores that are significantly below the norm (considered to represent a deficit) from those within normal limits. Subsequently, they can be compared to each other. If the intra-individual comparison yields a significant difference between a task (X) with a deficit and a task (Y) within normal limits, it is interpreted as a classical dissociation. If the scores in both tasks are significantly below the mean, and also significantly different from each other, it is interpreted as a strong dissociation [ 6 ]. The specific operational definitions provided by Crawford et al. [ 6 ] are Table 3 :

• - Classical dissociation : the patient’s score on a given test (A) is within normal limits while the patient’s score on a different test (B) has a deficit and the difference is significant using Crawford et al.’s [ 8 ] method and a two-tailed test (p < 0.05).
• - Strong dissociation : the patient’s score on two given tests (A and B) present with a deficit, but one score is significantly lower than the other using Crawford et al.’s [ 8 ] method and a two-tailed test (p < 0.05).

Crawford et al. [ 46 ] guidelines on the presentation of the data for the identification of classical and strong dissociations.

b Estimated percentage of control population exhibiting a discrepancy more extreme than the case.

Note: This level analysis provides significance tests, point and interval estimates of the percentage of pairs of controls that will exhibit a larger abnormality (or discrepancy), and the point and interval of the effect sizes [ 7 , 46 ].

In progressive conditions, such as HDL2, the relevance of this analysis is accentuated because the possibility of a generalised decline introduces the risk of having trivial differences between performances that may be misinterpreted [ 46 ]. With this test, it is possible to identify those functions that are specifically affected for each case, thus allowing for the identification of dissociations and introducing the issue of the severity of deficit for each individual, who is at a particular stage of the disease and therefore, at a specific moment of neuropathological progression. Therefore, the tasks yielding a strong dissociation would be interpreted as more severely affected than those displaying a classical dissociation.

Acknowledgements

We are grateful to Ms Marianne Gomes provided genetic counselling to all potential clinical participants and Ms Petra Gaylard who provided assistance with the preliminary statistical analyses. Prof Amanda Krause received the Medical Research Council’s Self-Initiated Research Grant entitled “The clinical and genetic profile of Huntington disease like 2 (HDL2) in South Africa”, which partially funded this study.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

1 This study adheres to the definitions of terms proposed by Krause et al. [ 20 ]: “Mixed ancestry individuals, in South Africa, are those whose gene pool is derived from one or more of the indigenous African populations (San, Khoikhoi or Bantu speaking), European immigrants from western Europe and/or slaves and indentured labourers from Madagascar, the Malaysian archipelago and India”. “Black individuals are those whose gene pool is derived from one or more of the indigenous Bantu-speaking African populations” (p. 1).

2 Raw scores were used in all data analyses in order to avoid superimposing specific distributions attached to adjusted scores and to allow for more variability in the scores, especially because some of the measurements have a narrow range and ceiling effects.

Appendix A Supplementary material related to this article can be found, in the online version, at doi: https://doi.org/10.1016/j.mex.2020.100782 .

Appendix A. Supplementary data

The following are Supplementary data to this article:

Department of Psychology

Introduction to clinical neuropsychology: case studies in cognitive neuroscience (ec).

Much of what we know about the brain systems underlying perception, attention, memory, and language has been first derived from patients with brain lesions or other brain pathology. Despite our advances in functional brain imaging the study of clinical cases in neuropsychology is still important to determine the causal role of certain brain regions in contributing to a given cognitive process.

School of Psychology

The personal pages of Professor John R Crawford

School of Psychology, University of Aberdeen

Single-Case Methodology in Neuropsychology

This research is conducted by Prof John R Crawford , School of Psychology, University of Aberdeen ) in collaboration with:

• Prof Paul H Garthwaite (Department of Statistics, Open University) , 
• Professor David C Howell (Department of Psychology, University of Vermont) , 
• Prof Keith R Laws (Department of Psychology, University of Hertfordshire) ,
• Prof Addelchi Azzalini (Dept of Statistics, University of Padua),
• Prof Annalena Venneri (University of Hull) ,
• Dr Colin Gray (University of Aberdeen ) and
• Patricia Bestelmeyer (University of Aberdeen)

For computer programs that implement the statistical methods described on this page click here

Click here for powerpoint file of Professor Crawford's Investigator Workshop delivered at the 34th International Neuropsychological Society Annual Meeting in Boston in February 2006

"Dissociation is the key word in neuropsychology" Rossetti & Revensuo, 2000, p. 1)

• (A) Background: The Single-Case Approach

The single-case approach in neuropsychology has made a significant contribution to our understanding of the architecture of human cognition.  However, as Caramazza and McCloskey (1988) note, if advances in theory are to be sustainable they “… must be based on unimpeachable methodological foundations” (p. 619).  The statistical treatment of single-case study data is one area of methodology that has been relatively neglected. In general terms, the motivation behind the work described below is to provide methods for single-case research that more closely match the standards demanded in group studies. 

There are three basic approaches to inference in single-case studies:

• The patient is administered fully standardized neuropsychological tests and performance is compared to large sample normative data
• At the other extreme, the patient’s performance is not referenced to normative data or control performance; i.e., analysis is limited to intra-individual comparisons
• The patient is compared to a (modestly sized) matched control sample

(1) The fully standardized approach:

Very useful and elegant methods have been devised for drawing inferences using approach (1); e.g. see Capitani, (1997), De Renzi, Faglioni, Grossi, & Nicheli, (1997), Willmes (1985).  However, because new constructs are constantly emerging in neuropsychology and the collection of large-scale normative data is a time-consuming and arduous process (Crawford, 2004) the prototypical single-case study remains one in which a patient is compared to a modestly-sized (matched) control sample.

(2) The intra-individual approach:

There are numerous single-case studies in the literature (some of which have been very influential) in which a patient’s performance is not referenced to a control sample; i.e. approach (2) is employed.  Typically in these studies within-individual inferential methods are employed (chi-square tests are typical) to compare a patient’s performance on Task X with their performance on Task Y .  For example, chi-square tests have been used in attempts to demonstrate a dissociation between naming of living-things and non-living things.  It is clear that the chi-square test’s assumption of independence is violated in these circumstances.

Moreover, in a recent collaboration on category specificity in Alzheimer’s disease with Keith Laws and colleagues (Laws, Gale, Leeson & Crawford, 2005, ( reprint as pdf ) we have demonstrated how these intra-individual analyses can be very misleading.  For example, patients can show a significant difference between living and non-living naming on chi-square tests (i.e. they are classified as exhibiting a dissociation) but such raw differences are not unusual when standardized against control performance (i.e. the within-individual method yields a false positive). Conversely, patients whose chi-square results are not significant, can show strong evidence of a dissociation between living and non-living naming when referenced to control performance.  Laws et al even found a case in which a putative dissociation in one direction was reversed when performance was referenced to control performance.  It can be concluded that single-case studies should never rely on within-individual analysis alone; a patient’s performance should always be referenced to control performance.

(3) The matched control sample approach (i.e., the case-controls design):

As noted above, in the third approach to inference, a patient’s performance is referenced to a matched control sample.  This approach is very widely employed in single-case research and is the focus of the methods outlined below.  By far the most common approach to the statistical analysis of such data uses z .  That is, the patient’s performance is converted to a z score based on the mean and SD of the control sample and this z is referred to a table of areas under the normal curve.  With this approach the control sample is treated as though it were a population (i.e. the sample statistics are treated as parameters).  However, as the size of the control samples in most single-case studies is modest (i.e. N is often < 10 and can even be < 5), this is not appropriate. The upshot is that these methods are associated with an inflated Type I error rate and overestimate the abnormality of the patient’s score.

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• (B) Our Basic Methods

Testing for a deficit:

Methods have been developed for comparing an individual patient's score with a control sample: these address the question of whether or not a patient exhibits a statistically significant deficit (Crawford & Howell, 1998) (Reprint as pdf ).  In contrast to the use of z , Crawford & Howell’s (1998) method treats the control sample statistics as statistics rather than as parameters.  Recent work using Monte Carlo simulations (Crawford & Garthwaite, 2005a) confirms that this test controls the Type I error rate regardless of the size of the control sample.

Furthermore, it is very common for the control data in single-case studies to exhibit severe depatures from normality. Simulation studies have shown that Crawford & Howell’s method is surprisingly robust even in the face of very severe skew and /or leptokurtosis (Crawford et al, 2006) ( reprint ). This latter study also evaluates potential non-parametric alternatives to our methods.

Crawford and Howell's (1998) method performs two roles simultaneously: (1) it tests whether a patient's score is significantly below controls, and (2) it provides a point estimate of the abnormality of the score; i.e. it estimates the percentage of the control population that would obtain a score lower than the patient (a formal proof that the p value for the significance test is also a point estimate of abnormality can be found in Crawford & Garthwaite,(2006b) (reprint ) .

A method for setting confidence limits on the abnormality of a patient’s score has also been developed (Crawford & Garthwaite, 2002) ( reprint as pdf ); this latter methods make use of non-central t -distributions. A computer program accompanies this latter paper (singlims.exe); the program performs the significance test and provides the point estimate of abnormaility and 95% confidence limits on this abnormality.

The program singlims.exe implements these methods; that is, it tests whether a patient's score is significantly below controls, provides a point estimate of the abnormality of the patient's score (ie it estimates the percentage of the control population exhibiting a lower score), and provides accompanying confidence limits on this quantity. An upgraded version of singlims is now available, Singlims_ES.exe ; that supplements the foregoing results with point and interval stimates of effect sizes ; as described in Crawford, Garthwaite & Porter (2010) ( reprint ).

One issue that, until relatively recently, has not been studied formally is the power to detect a deficit in single-case studies (that is, although there is now a body of work examining Type I error rates, little attention has been given to Type II errors). Crawford and Garthwaite (2006) ( reprint) have examined the power of Crawford & Howell's method, and an alternative method proposed by Mycroft et al (2002). Power to detect a (large) deficit was typically moderate for the former method but was very low for the latter method. The paper also examines the effects of measurement error on power to detect deficits, including scenarios in which a patient's scores are more unreliable than those of controls. Finally (Study 5) it is demonstrated that low power to detect a deficit (i.e., a high Type II error rate), such as typifies Mycroft et al's method, can have the paradoxical effect of inducing very high Type I error rates when attempting to detect a classical dissociation.

Testing for differences among a patient's scores:

Methods have also been developed for comparing the difference between a patient's performance on two (Crawford, Howell & Garthwaite, 1998) ( Reprint as pdf ) or more tasks (Crawford & Garthwaite, 2002) ( Reprint as pdf ) with the distribution of differences in controls.  These methods address the further question of whether there is evidence of a dissociation or a differential deficit in the patient.  The methods are all modified t -tests (i.e. unlike the use of z they treat the control sample as a sample rather than as a population).  In addition to providing a significance test they also simultaneously provide a point estimate of the rarity / abnormality of a patient's score or score difference. 

A superior test on the difference between a patient’s performance on two tasks has been developed (Crawford & Garthwaite, 2005; Garthwaite & Crawford, 2004).  This test, the Revised Standardized Difference Test (RSDT) controls the Type I error rate regardless of (a) the control sample N and (b) magnitude of the correlation between tasks X and Y .  It should therefore be used in preference to Crawford, Howell & Garthwaite’s (1998) method. This test has been implemented in a computer program ( RSDT.exe ) and is also incorporated into a program that tests for dissociations ( dissocs.exe ). Both of these programs have now been upgraded to provide point and interval estimates of effect sizes ; see upgraded versions (RSDT_ES.exe and dissocs_ES.exe) and click here for preprint of paper on effect sizes in the case-controls design.

It should be noted that, in testing whether the difference between a patient's performance on two tasks differs significantly from the distribution of differences in controls, it is normally necessary to standardize the scores. That is, the two tasks involved typically have different means and standard deviations. For example, a researcher may want to compare a patient's performance on a Theory of Mind task (with mean of 25 and SD of 4.5) to performance on a measure of executive function (mean = 52 and SD = 12).

Finding a suitable method for this type of analysis has proved to be much more difficult than it appears. Although we believe that further advances can be made, the results for The Revised Standardized Difference Test (RSDT) are very positive. The graphic below shows the results from a Monte Carlo simulation in which we examined control of the Type I error rate for three methods: the widely used test of Payne and Jones (1957), Crawford, Howell and Garthwaite's (1998) method and the RSDT (Crawford and Garthwaite, 2005). It can be seen that Type I errors (which should be at the specified rate of 5%) are very high for the Payne and Jones test particulalrly for control sample sizes that are typical in single-case studies (in this context a Type I error occurs if a member of the control population is classified as differing from controls). Furthermore, although Crawford et al's (1998) test is a marked improvement over this earlier test, the Type I error rate is still inflated. In contrast, the RSDT achieves control of the Type I error rate.

• (C) Extensions to the Basic Methods

Comparing a patient to controls when data are in the form of slopes of regression lines or correlation coefficients

The methods have been further extended to allow inferences to be drawn when the patient's performance is quantified, not by a conventional score, but as the slope of a regression line (Crawford & Garthwaite, 2004; Reprint as a pdf ) (e.g. in distance or time estimation tasks where actual distance or elapsed time is regressed on estimated distance or time) or as a correlation coefficient (Crawford, Garthwaite, Howell & Venneri, 2003; Reprint as pdf ) (e.g. in assessing temporal order memory when the rank order correlation between actual and reported order of presentation is used to quantify performance).  Note that in both cases performance is quantified by an intra-individual measure of association but, crucially and unlike the intra-individual methods discussed above, a patient’s performance is still compared against the performance of controls when applying the inferential statistics. These methods have been implemented in computer programs: singlslope.exe deals with data in the form of slopes and iima.exe deals with data in the form of correlation coefficients

Comparing patients' obtained scores with their scores predicted by a regression equation

We (Crawford and Garthwaite, 2006a) ( reprint as pdf ) have also developed methods for drawing inferences concerning the discrepancy between an individual's obtained score and their scores predicted by a regression equation. Regression equations are widely used in neuropsychology to draw inferences concerning the cognitive status of individual patients. For example, an equation predicting retest scores from scores at original testing can be used to test whether there has been change in a patient's level of functioning. Equations can also be used as an alternative to conventional normative data by providing "continuous norms" as when a patient's score on a neuropsychological test is compared to the score predicted by their age (sse paper for further examples).

These programs test if there is a significant discrepancy between an individual's obtained and predicted score (one- and two-tailed p values are provided). They also provide a point estimate of the abnormality of the discrepancy (i.e., a point estimate of the percentage of the population exhibiting a larger discrepancy) and accompanying confidence limits on this quantitiy. The methods have been implemented in computer programs ( regdiscl.exe and regdisclv.exe ).

A commonly used alternative to these methods of analyzing the discrepancy between obtained and predicted scores involves dividing the discrepancy by the equation's standard error of estimate and treating the result as a standard normal deviate (the p value for this z is then obtained from a table of areas under the normal curve). Monte Carlo simulations ( Crawford & Garthwaite, 2006a ) show that, unlike the method implemented in these programs, the latter method does not control Type I errors and overestimates the abnormality of an individual's discrepancy. In addition, because it does not acknowledge the uncertainty associated with sample regression statistics, it cannot provide confidence limits on the abnormality of the discrepancy.

We have extended this work ( Crawford & Garthwaite, 2007 ) to allow researchers or clinicians to build regression equations from summary data (correlation between a predictor and criterion variable together with these variables means and SDs). There is a large reservoir of published data that could be used to build regression equations, these equations could then be used to draw inferences concerning a single-case. The methods have been implemented in computer programs (regbuild.exe and regbuild_t.exe )

Comparing two cases

We have recently developed methods that allow single case reseasrchers to compare the scores of two single cases ( Crawford, Garthwaite & Wood, 2010 ). Unlike existing methods of comparing two cases, these new methods refer the scores of the two cases to a control sample. (See the accompanying paper for a discussion of the issues arising when control data are not used). All of the methods provide a significance test (one and two-tailed), point and interval estimates of the effect size for the difference, and point and interval estimates of the percentage of pairs of controls that will exhibit a larger difference than that observed for the cases (i.e., these latter statistics quantify the abnormality of the difference). The methods are predominantly classical (although a Bayesian approach is also developed - this provides results that converge with the classical approach). There is the option of allowingl for the effects of covariates when comparing the two cases. The computer programs accompanying the paper can be used with summary data or raw data from the controls.

Comparing a case to controls allowing for the effects of covariates

We have recently developed Bayesian methods that allow a researcher to compare a case's score to controls allowing for the effects of covariates ( Crawford, Garthwaite & Ryan, in press). The methods include comparison of a case's standardized difference between two tasks to differences observed in controls (i.e., one can test for a dissocation in the case, allowing for the effects of covariates)

The covariate methods provide the same full range of results provided by our earlier methods. That is they provide: (a) a signficance test (i.e. tests whether we can reject the null hypothesis that the case's score, or score difference, is an observation from the scores, or score differences, in the control population); (b) point and interval estimate of the abnormality of the case's score, or score difference; and (c) point and interval estimates of the effect size for the difference between case and controls

These methods have a very wide range of potential applications, e.g., they can provide a means of increasing the statistical power to detect deficits or dissociations, or can be used to test whether differences between a case and controls survive partialling out the effects of potential confounding variables

• (D) Criteria for Classical and Strong Dissociations

Crawford, Garthwaite & Gray (2003) reviewed existing definitions of dissociations used in single-case studies and argued that they are vague (i.e. the statistical methods used to determine whether a patient meets the definitions are rarely specified) and are insufficiently rigorous.  In response they proposed formal criteria for deficits, strong and classical dissociations and double dissociations ( Reprint as a pdf ).  For example, the typical (conventional) definition of a classical dissociation is that a patient is impaired on Task X and “within normal limits” or “unimpaired” on Task Y .  There are two related problems with this definition, (1) the second half of the definition boils down to an attempt to prove the null hypothesis, and (2) the difference between a patient’s performance on Tasks X and Y could be very trivial (i.e. the score on Task X could be just below a particular cut-off and Task Y just above it). In these circumstances one would not want to claim that a dissociation had been established.

Crawford, Garthwaite & Gray’s (2003) criteria provided operational definitions of a deficit and “within normal limits” and proposed that a classical dissociation is established when the patient has a deficit on Task X , is within normal limits on Y , and that there is a significant difference between performance on Task X and Y.  The latter criterion deals with the two problems outlined above.  These criteria draw on the statistical methods described in Section B (above).  Monte Carlo simulations indicated that very few individuals drawn from the healthy population would be misclassified as exhibiting a strong or classical dissociation when these criteria are applied.  Crawford & Garthwaite (2005) revised these criteria by replacing Crawford, Howell & Garthwaite’s (1998) test on the difference between tasks with the Revised Standardized Difference Test ( reprint as pdf ).  An accompanying computer program ( dissocs.exe ) automates testing for dissociations; this program has been upgraded ( dissocs_ES.exe ) to include point and interval estimate of effect sizes (see Crawford, Garthwaite & Porter, 2010 ).

Crawford & Garthwaite (2005b) reprint as pdf ) have examined the Type I error rates for the conventional criteria for a classical dissocation and find that the rates are high (up to 18.6%) when a Type I error rate is defined as misclassifying a control case as exhibiting a classical dissociation. We have also conducted further simulation studies in which we "lesion" cases; this allows us to study a different form of Type I error; namely misclassifying a patient with equivalent deficits on the tasks of interest as exhibiting a dissocation (as equivalent deficits were imposed, such cases do not exhibit a true dissociation). The error rates for the conventional criteria were alarmingly high in these simulations (range 19.3% to 49.6%). In contrast the rates were markedly lower for our criteria (range 2.7% to 7.1%). Some of the results are displayed in the figure below (in this example the population correlation between Task X and Y was 0.5). These results demonstrate the importance of testing for a significant difference between a patient’s performance on Tasks X and Y when attempting to identify classical dissociations. Further simulations indicated that both sets of criteria are robust in the face of departures from normality.

Crawford & Garthwaite, 2006c) ( reprint as pdf ) quantified the Type I error rates and power for competing methods of detecting strong dissociations and quantified the overall error rate and power when attempting to detect either form of dissociation (ie strong or classical). Using our criteria, power to detect either form of dissociation is moderate-to-high in most scenarios and Type I error rates are reasonable.

This study also found that, regardless of the criteria used, many patients classified as exhibiting classical dissociations will in reality be cases of strong dissociation (i.e., there will be a failure to detect the deficit on one of the tasks). In contrast, cases of strong dissocations will rarely be misclassified as exhibiting a classical dissocation. In light of these findings we suggest that the term "classical dissocation" should be changed to "a dissociation, putatively classical" - this terminology captures the fact that although (if Crawford & Garthwaite's criteria are employed) one can be confident that a patient has suffered a dissocation of some form, but one cannot be confident that it is classical in form.

The need to standardize scores when testing for a difference / dissociation: The cow-canary problem

Our classical and Bayesian methods for testing for a difference between a case's scores on two tasks standardize the case's scores. In contrast, if the analysis is based on the difference between raw scores there is the danger of artefacts arising from what Capitani et al. (1999) have termed the Cow-Canary problem. If the tasks differ in their standard deviations, the task with the larger standard deviation will exert more weight on the raw difference score. Indeed, if the difference in SDs is very large, the difference score will alomost entirely be a reflection of the task with the larger SD. Crawford, Garthwaite & Howell (2009) provided dramtic illustrations of these dangers in which a case's scores were analyzed using a mixed ANOVA (case vs controls as the between-subjects factor, task as within-subjects factor): the p value for the interaction was used to test for a dissociation. For example, a case with identical z scores on two tasks was recorded as exhibiting a dissociation between the tasks .

• (E) Computer Programs for the Single-Case Researcher

Computer programs that accompany the papers on single-case methods have been written and made available; these implement all the statistical methods discussed above.  By using these programs single-case researchers can use the statistical methods to analyse their data in seconds (and also reduce the possibility of clerical error).

• (F) References for the methods

• (G) Some examples of the use of the above methods

In this section:

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Fractured minds: A case-study approach to clinical neuropsychology

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Testing for suspected impairments and dissociations in single-case studies in neuropsychology: evaluation of alternatives using monte carlo simulations and revised tests for dissociations

Affiliation.

• 1 School of Psychology, University of Aberdeen, Aberdeen, Scotland. [email protected]
• PMID: 15910118
• DOI: 10.1037/0894-4105.19.3.318

In neuropsychological single-case studies, a patient is compared with a small control sample. Methods of testing for a deficit on Task X, or a significant difference between Tasks X and Y, either treat the control sample statistics as parameters (using z and zD) or use modified t tests. Monte Carlo simulations demonstrated that if z is used to test for a deficit, the Type I error rate is high for small control samples, whereas control of the error rate is essentially perfect for a modified t test. Simulations on tests for differences revealed that error rates were very high for zD. A new method of testing for a difference (the revised standardized difference test) achieved good control of the error rate, even with very small sample sizes. A computer program that implements this new test (and applies criteria to test for classical and strong dissociations) is made available.

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Psychology’s 10 greatest case studies – digested

These ten characters have all had a huge influence on psychology and their stories continue to intrigue each new generation of students. What’s particularly fascinating is that many of their stories continue to evolve – new evidence comes to light, or new technologies are brought to bear, changing how the cases are interpreted and understood. What many of these 10 also have in common is that they speak to some of the perennial debates in psychology, about personality and identity, nature and nurture, and the links between mind and body.

Phineas Gage

One day in 1848 in Central Vermont, Phineas Gage was tamping explosives into the ground to prepare the way for a new railway line when he had a terrible accident. The detonation went off prematurely, and his tamping iron shot into his face, through his brain, and out the top of his head.

Remarkably Gage survived, although his friends and family reportedly felt he was changed so profoundly (becoming listless and aggressive) that “he was no longer Gage.” There the story used to rest – a classic example of frontal brain damage affecting personality. However, recent years have seen  a drastic reevaluation  of Gage’s story in light of new evidence. It’s now believed that he underwent significant rehabilitation and in fact began work as a horse carriage driver in Chile. A  simulation of his injuries  suggested much of his right frontal cortex was likely spared, and  photographic evidence  has been unearthed showing a post-accident dapper Gage. Not that you’ll find this revised account in many psychology textbooks:  a recent analysis  showed that few of them have kept up to date with the new evidence.

Henry Gustav Molaison (known for years as H.M. in the literature to protect his privacy), who died in 2008, developed severe amnesia at age 27 after undergoing brain surgery as a form of treatment for the epilepsy he’d suffered since childhood. He was subsequently the focus of study by over 100 psychologists and neuroscientists and he’s been mentioned in over 12,000 journal articles! Molaison’s surgery involved the removal of large parts of the hippocampus on both sides of his brain and the result was that he was almost entirely unable to store any new information in long-term memory (there were some exceptions – for example, after 1963 he was aware that a US president had been assassinated in Dallas). The extremity of Molaison’s deficits was a surprise to experts of the day because many of them believed that memory was distributed throughout the cerebral cortex. Today, Molaison’s legacy lives on: his brain was carefully sliced and preserved and turned into a 3D digital atlas and his life story is reportedly due to be turned into a feature film based on the book researcher Suzanne Corkin wrote about him:  Permanent Present Tense, The Man With No Memory and What He Taught The World .

Victor Leborgne (nickname “Tan”)

The fact that, in most people, language function is served predominantly by the left frontal cortex has today almost become common knowledge, at least among psych students. However, back in the early nineteenth century, the consensus view was that language function (like memory, see entry for H.M.) was distributed through the brain. An eighteenth century patient who helped change that was Victor Leborgne, a Frenchman who was nicknamed “Tan” because that was the only sound he could utter (besides the expletive phrase “sacre nom de Dieu”). In 1861, aged 51, Leborgne was referred to the renowned neurologist Paul Broca, but died soon after. Broca examined Leborgne’s brain and noticed a lesion in his left frontal lobe – a segment of tissue now known as Broca’s area. Given Leborgne’s impaired speech but intact comprehension, Broca concluded that this area of the brain was responsible for speech production and he set about persuading his peers of this fact – now recognised as a key moment in psychology’s history. For decades little was known about Leborgne, besides his important contribution to science. However, in a paper published in 2013, Cezary Domanski at Maria Curie-Sklodowska University in Poland uncovered new biographical details, including the possibility that Leborgne muttered the word “Tan” because his birthplace of Moret, home to several tanneries.

Wild Boy of Aveyron

The “Wild boy of Aveyron” – named Victor by the physician Jean-Marc Itard – was found emerging from Aveyron forest in South West France in 1800, aged 11 or 12, where’s it’s thought he had been living in the wild for several years. For psychologists and philosophers, Victor became a kind of “natural experiment” into the question of nature and nurture. How would he be affected by the lack of human input early in his life? Those who hoped Victor would support the notion of the “noble savage” uncorrupted by modern civilisation were largely disappointed: the boy was dirty and dishevelled, defecated where he stood and apparently motivated largely by hunger. Victor acquired celebrity status after he was transported to Paris and Itard began a mission to teach and socialise the “feral child”. This programme met with mixed success: Victor never learned to speak fluently, but he dressed, learned civil toilet habits, could write a few letters and acquired some very basic language comprehension. Autism expert Uta Frith believes Victor may have been abandoned because he was autistic, but she acknowledges we will never know the truth of his background. Victor’s story inspired the 2004 novel  The Wild Boy  and was dramatised in the 1970 French film  The Wild Child .

Nicknamed ‘Kim-puter’ by his friends, Peek who died in 2010 aged 58, was the inspiration for Dustin Hoffman’s autistic savant character in the multi-Oscar-winning film  Rain Man . Before that movie, which was released in 1988, few people had heard of autism, so Peek via the film can be credited with helping to raise the profile of the condition. Arguably though, the film also helped spread the popular misconception that giftedness is a hallmark of autism (in one notable scene, Hoffman’s character deduces in an instant the precise number of cocktail sticks – 246 – that a waitress drops on the floor). Peek himself was actually a non-autistic savant, born with brain abnormalities including a malformed cerebellum and an absent corpus callosum (the massive bundle of tissue that usually connects the two hemispheres). His savant skills were astonishing and included calendar calculation, as well as an encyclopaedic knowledge of history, literature, classical music, US zip codes and travel routes. It was estimated that he read more than 12,000 books in his life time, all of them committed to flawless memory. Although outgoing and sociable, Peek had coordination problems and struggled with abstract or conceptual thinking.

“Anna O.” is the pseudonym for Bertha Pappenheim, a pioneering German Jewish feminist and social worker who died in 1936 aged 77. As Anna O. she is known as one of the first ever patients to undergo psychoanalysis and her case inspired much of Freud’s thinking on mental illness. Pappenheim first came to the attention of another psychoanalyst, Joseph Breuer, in 1880 when he was called to her house in Vienna where she was lying in bed, almost entirely paralysed. Her other symptoms include hallucinations, personality changes and rambling speech, but doctors could find no physical cause. For 18 months, Breuer visited her almost daily and talked to her about her thoughts and feelings, including her grief for her father, and the more she talked, the more her symptoms seemed to fade – this was apparently one of the first ever instances of psychoanalysis or “the talking cure”, although the degree of Breuer’s success has been disputed and some historians allege that Pappenheim did have an organic illness, such as epilepsy. Although Freud never met Pappenheim, he wrote about her case, including the notion that she had a hysterical pregnancy, although this too is disputed. The latter part of Pappenheim’s life in Germany post 1888 is as remarkable as her time as Anna O. She became a prolific writer and social pioneer, including authoring stories, plays, and translating seminal texts, and she founded social clubs for Jewish women, worked in orphanages and founded the German Federation of Jewish Women.

Kitty Genovese

Sadly, it is not really Kitty Genovese the person who has become one of psychology’s classic case studies, but rather the terrible fate that befell her. In 1964 in New York, Genovese was returning home from her job as a bar maid when she was attacked and eventually murdered by Winston Mosely. What made this tragedy so influential to psychology was that it inspired research into what became known as the Bystander Phenomenon – the now well-established finding that our sense of individual responsibility is diluted by the presence of other people. According to folklore, 38 people watched Genovese’s demise yet not one of them did anything to help, apparently a terrible real life instance of the Bystander Effect. However, the story doesn’t end there because historians have since established  the reality was much more complicated  – at least two people did try to summon help, and actually there was only one witness the second and fatal attack. While the main principle of the Bystander Effect has stood the test of time, modern psychology’s understanding of the way it works has become a lot more nuanced. For example, there’s evidence that in some situations people are more likely to act when they’re part of a larger group, such as when they and the other group members all belong to the same social category (such as all being women) as the victim.

Little Albert

“Little Albert” was the nickname that the pioneering behaviourist psychologist John Watson gave to an 11-month-old baby, in whom, with his colleague and future wife Rosalind Rayner, he deliberately attempted to instill certain fears through a process of conditioning. The research, which was of dubious scientific quality, was conducted in 1920 and has become notorious for being so unethical (such a procedure would never be given approval in modern university settings). Interest in Little Albert has reignited in recent years as an academic quarrel has erupted over his true identity. A group led by Hall Beck at Appalachian University announced in 2011 that they thought Little Albert was actually Douglas Merritte, the son of a wet nurse at John Hopkins University where Watson and Rayner were based. According to this sad account, Little Albert was neurologically impaired, compounding the unethical nature of the Watson/Rayner research, and he died aged six of  hydrocephalus (fluid on the brain). However, this account was challenged by a different group of scholars led by Russell Powell at MacEwan University in 2014. They established that Little Albert was more likely William A Barger (recorded in his medical file as Albert Barger), the son of a different wet nurse. Earlier this year, textbook writer Richard Griggs weighed up all the evidence and concluded that the Barger story is the more credible, which would mean that Little Albert in fact died 2007 aged 87.

Chris Sizemore

Chris Costner Sizemore is one of the most famous patients to be given the controversial diagnosis of multiple personality disorder, known today as dissociative identity disorder. Sizemore’s alter egos apparently included Eve White, Eve Black, Jane and many others. By some accounts, Sizemore expressed these personalities as a coping mechanism in the face of traumas she experienced in childhood, including seeing her mother badly injured and a man sawn in half at a lumber mill. In recent years, Sizemore has described how her alter egos have been combined into one united personality for many decades, but she still sees different aspects of her past as belonging to her different personalities. For example, she has stated that her husband was married to Eve White (not her), and that Eve White is the mother of her first daughter. Her story was turned into a movie in 1957 called  The Three Faces of Eve  (based on a book of the same name written by her psychiatrists). Joanne Woodward won the best actress Oscar for portraying Sizemore and her various personalities in this film. Sizemore published her autobiography in 1977 called  I’m Eve . In 2009, she appeared on the BBC’s  Hard Talk  interview show.

David Reimer

One of the most famous patients in psychology, Reimer lost his penis in a botched circumcision operation when he was just 8 months old. His parents were subsequently advised by psychologist John Money to raise Reimer as a girl, “Brenda”, and for him to undergo further surgery and hormone treatment to assist his gender reassignment.

Money initially described the experiment (no one had tried anything like this before) as a huge success that appeared to support his belief in the important role of socialisation, rather than innate factors, in children’s gender identity. In fact, the reassignment was seriously problematic and Reimer’s boyishness was never far beneath the surface. When he was aged 14, Reimer was told the truth about his past and set about reversing the gender reassignment process to become male again. He later campaigned against other children with genital injuries being gender reassigned in the way that he had been. His story was turned into the book  As Nature Made Him, The Boy Who Was Raised As A Girl  by John Colapinto, and he is the subject of two BBC Horizon documentaries. Tragically, Reimer took his own life in 2004, aged just 38.

Christian Jarrett  ( @Psych_Writer ) is Editor of  BPS Research Digest

This article was originally published on  BPS Research Digest . Read the  original article .

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What to Expect at Your Neuropsychology Evaluation

What is a neuropsychological evaluation.

It's important for your child's overall health and development to understand how some medical conditions affect the brain, intellectual and cognitive functions, and psychological and psychosocial factors. A neuropsychological evaluation is an approach to identify and track these interactions in your child's development now and in the future.

The assessment may involve a broad evaluation of cognitive abilities or a more targeted assessment of specific areas of concern. The neuropsychology team at Children's Hospital of Philadelphia (CHOP) can help determine what kind of evaluation will be the best for your child.

A neuropsychological evaluation might assess any or all of the following areas:

• Intellectual functioning
• Attention and executive function skills (such as planning, organization, impulse control, cognitive flexibility)
• Reasoning and problem-solving
• Visual-spatial/visual-perceptual skills
• Sensory-perceptual functioning
• Fine motor abilities
• Learning and memory
• Academic achievement
• Social skills
• Emotional and behavioral functioning
• Adaptive skills (independence in daily living activities)

Neuropsychological evaluation is not considered to be medically necessary when used primarily for:

• Educational evaluation of possible learning disabilities or as part of vocational assessment to help plan job training
• Baseline assessment of function or screening purposes in individuals without medical conditions known to affect the brain
• Monitoring of chronic conditions when there is no significant new change in behavioral, mental state or cognitive functioning

What is included in a neuropsychological evaluation?

Neuropsychological evaluation usually includes an interview with the child and their parents or caregivers, observation of the child’s behavior and in-person testing.

Testing may involve hands-on activities, answering questions, computerized tasks, and paper-and-pencil tests. The neuropsychologist may also ask caregivers and teachers to complete standardized questionnaires about your child’s development, emotional functioning and behavior. Testing is usually completed in one day.

Once testing is done, the neuropsychologist summarizes the evaluation findings and recommendations in a feedback discussion with the family and in a written report. Depending on your child's age, the findings, impressions, diagnoses and recommendations will be shared with them.

The report will be shared with your child's referring medical provider and will be available to others also involved in delivering care, such as your child's specialists and primary care pediatrician. With your family's permission, information can also be shared with schools or outside services or agencies to facilitate further treatment and support for your child.

How do I add my child to the waitlist for a CHOP neuropsychological evaluation?

We ask that a medical provider or specialist involved in your child’s care submit a letter of medical necessity covering the reasons the evaluation is needed, along with relevant medical diagnoses (to help the insurance company understand the reason for the evaluation). Clinical documentation or office notes are also acceptable if a letter of medical necessity is not possible.

If your child’s provider is affiliated with CHOP, the letter of medical necessity can be submitted directly through your child's electronic medical record. If a provider outside of CHOP is referring your child, all documentation can be faxed to 445-428-4263. All incoming referrals are reviewed by a neuropsychologist to make sure they are clinically appropriate. Our administrative staff reviews the letter for insurance verification.

If your child’s clinical referral is appropriate for a CHOP neuropsychological evaluation, you will receive a letter from our group outlining the estimated wait, general information about the service and an option to be added to the cancellation list.

There may be a significant waiting period between your child’s clinical referral for an evaluation and your appointment. The exact length of time you’ll wait for an appointment depends on the type of evaluation your child needs.

If you have any additional questions about the referral process, evaluation procedures or the service in general, please direct your questions to [email protected] or call 215-590-7555.

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A win for science, and patients, against brain injury ‘nihilism’.

Illustrations by Liz Zonarich/Harvard Staff

Alvin Powell

Harvard Staff Writer

Hope for progress even after a 450-foot fall, trial shows, defying pessimism that hurts research and families

New research may upend the widely held view of traumatic brain injury as a permanently debilitating condition. The findings indicate that electrical stimulation can reawaken quiescent brain circuitry, leading to functional improvements that have the potential to restore work and social activities to patients’ lives. 

The early stage trial, by investigators at Harvard-affiliated Spaulding Rehabilitation Hospital and colleagues at institutions around the country, including Weill Cornell Medicine, Stanford University, the Cleveland Clinic, and the University of Utah, was completed by five of the six enrolled patients. It yielded improvements of between 15 percent and 52 percent on a standard test of executive function, which involves attention, inhibition, reasoning, problem-solving, and other key aspects of mental processing.  

Examples of executive function

The  study , published in December in Nature Medicine, relied on “deep brain stimulation,” in which a battery-powered device is implanted under a patient’s skin. Electrodes extend from the device to a part of the thalamus, which routes signals from one section of the brain to another. 

“There’s a lot of ways to shut parts of the system down,” said  Joseph Giacino , Spaulding’s director of rehabilitation neuropsychology and a professor of physical medicine and rehabilitation at Harvard Medical School, who helped design the study. “One is by direct damage to specific structures. Then you have the more common situation where I can damage the pathways that connect those structures and I get the same effect. 

“If the thalamus — this key relay station and signaling system — is damaged, it can’t activate or upregulate those circuits that are relatively spared and could work and perform their role if they had the right input.”

The volunteers had suffered moderate to severe brain injury from either a motor vehicle accident or a fall — one from 450 feet and another from roughly 60 feet. The accidents occurred between three and 18 years earlier, long enough that the victims were considered past the immediate post-injury phase when most healing takes place. Each had recovered enough to perform the activities of daily living — personal hygiene, dressing, and feeding themselves — but had not regained pre-injury levels of work, study, and social activities. 

A common view of brain injury, held by both laypeople and the medical community, is that the affected cells cannot regrow, leading to permanent disability. In this case, investigators tested an alternate theory: The idea that some — perhaps many — injuries disrupt signaling between parts of the brain, and it is the loss of communication, rather than cell death, that causes much of the decline in function. If that’s the case, they say, then it’s possible that stimulating brain regions important in communication can restore some function.

The five volunteers received deep-brain stimulation for 12 hours a day for three months. To gauge results, the researchers selected a standard test of executive function called the “trail making test part B” and established 10 percent improvement as a clinically relevant threshold.

By the study’s end, all five patients had exceeded the 10 percent threshold, producing an average improvement of 31.75 percent. The greatest gains, more than 40 percent, were seen in the two who had suffered falls and had the deepest initial deficits. But even those with mild impairment improved by more than 20 percent. Two participants, one injured in a car accident and a second hit by a car while riding a bicycle, regained the ability to work, albeit at reduced capacity, and socialize. The functional status of the other volunteers remained stable.

How does the device work?

One mother called her daughter’s improvement “profound” and “a miracle.” None of the participants were “cured,” however. Rather, the implant plays a long-term role analogous to that of a cardiac pacemaker. Even though the trial’s experimental phase concluded years ago, all five participants still have their devices. Some have had new batteries installed.

The researchers don’t understand precisely how deep-brain stimulation improves functioning, but they are skeptical that the artificial signals replace neural messages. The team’s favored explanation, Giacino said, is that the stimulation serves to activate the thalamus, which in turn upregulates viable downstream parts of the brain, restoring at least some signaling capacity.

“I think what it’s doing is putting the brain into a state of readiness, so when the demands are there to engage a particular network or subsystem, it can do that,” he said. 

Patients in the study saw improvements to capabilities that had been considered set in stone for as long as 18 years. This doesn’t mean that deep-brain stimulation is likely to be a universal answer, Giacino noted. And though the work suggests that not all loss of function is due to cell death in specific parts of the brain, some of it undoubtedly is. But overall, the results suggest that it’s time to rethink the idea that brain injury is permanent, he said. A Phase 2 study, set to involve about 50 people, is now in the planning stages.

“The degree of nihilistic belief that exists, both among the lay public and clinicians who see persons with severe brain injury, is remarkable and hugely problematic,” Giacino said. “This belief that if you have a severe brain injury you’re fated to do poorly — you’ll get some period of time in which your brain will naturally try to heal itself and then you’re at your final outcome — has been a problem for clinical practice, for research, for funding, and for people who have severe brain injury and their families.”

The progress of patients in the trial, he added, “helps chip away at the nihilism that really makes our work so much more difficult.”

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Fractured Minds: A case-study approach to clinical neuropsychology by Jenni A. Ogden (3-Mar-2005) Paperback Paperback

• Publisher OUP USA; 2 edition (3 Mar. 2005)
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• ASIN ‏ : ‎ B013J91DWM

About the author

Jenni ogden.

Jenni Ogden lives with her husband on a rugged, remote, off-grid island 100 kms off the north-east coast of New Zealand. It is a place her four adult children and five grandchildren love to visit. During the NZ winters she escapes to the Australian tropics or travels to the US or UK, travel being another passion, along with reading (writing!) and conservation. Her new novel, CALL MY NAME, another great read for bookclubs, is set mainly in Queensland, Australia. It is the story of two women, bound together by contrasting personalities, friendship, love and home—until motherhood rips them apart. THE MOON IS MISSING, published in 2020, was set in London, New Orleans during Hurricane Katrina, and on the very island Jenni lives on in NZ. A DROP IN THE OCEAN, her debut novel, set on another remote island on Australia’s Great Barrier Reef, features a woman over forty, and explores Jenni’s favorite themes: friendship, family, love, hard choices, and coping with neurological or medical illness. In 2016 it won the Gold in the Nautilus Book Awards for Fiction, Large Publisher, (shared with Monica Wood's novel, 'The One-In-A-Million-Boy'), the Gold for the Sarton Women's Book Awards in Contemporary Fiction, the Gold in the Independent Publisher Book Awards (IPPYS) for Best Fiction: Australia and NZ, and the Silver in the Readers' Favorites International Book Awards for Women's Fiction.

Writes Jacquelyn Mitchard, New York Times #1 best-selling author of 'The Deep End of the Ocean' and 'Two If By Sea'— “Reading A Drop in the Ocean was everything a reading experience should be, endearing and enduring, time spent with characters who seem to be people I already knew.”

And from Ann Hood, New York Times best-selling author of 'The Knitting Circle' and 'The Obituary Writer'—“In A Drop in the Ocean, protagonist Anna Fergusson learns that love is about letting go. Jenni Ogden takes us on a sweeping journey, rich with unique characters and places, moving backward and forward in time, to reach this poignant and heartfelt lesson.”

Before she took up fiction writing, Dr. Ogden enjoyed an international reputation as a neuropsychologist, and was awarded the Distinguished Career Award by the International Neuropsychological Society in 2015. Her non-fiction books include the classic text, FRACTURED MINDS, and a book for the general reader, TROUBLE IN MIND. Both relate the courageous struggles and triumphs of people who have suffered brain disorders.

Sign up for her occasional “Off-Grid” e-newsletter (http://www.jenniogden.com/newsletter.htm) and read her blog posts on Psychology Today (https://www.psychologytoday.com/blog/trouble-in-mind-0).

And if you want to see pics of her beautiful island check out her website (www.jenniogden.com)

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Customers find the book's explanations of specific case studies well organized, understandable, and good for school and real life learning. They also appreciate the basic definitions in neurology and terminology that are helpful, but not boring. Overall, readers say the book is well written and informative.

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