Prospects for faking believable memory deficits on neuropsychological tests and the use of incentives in simulation research

Abstract

The vulnerability of several neuropsychological memory tests – the Wechsler Memory Scale – Revised, Complex Figure Test, Auditory Verbal Learning Test, and Rey Memory Test – to faked deficits was evaluated. Subjects were randomly assigned to one of three conditions: Control (n=28), Malingering with a financial incentive (n=30), and Malingering without a financial incentive (n=28). Overall, the performance of the Malingering Groups was not significantly different from one another, but both groups were significantly poorer than Controls. Discriminant functions with a reduced set of predictors correctly classified about 75% of cases in both the Control and the combined Malingering Groups on cross-validation. The results suggest that neuropsychological memory tests are vulnerable to faked deficits, and that recognition tasks are disproportionately affected. The use of incentives in simulation research is also discussed.     

Known-groups cross-validation of the letter memory test in a compensation-seeking mixed neurologic sample

Compensation-seeking neuropsychological evaluees were classified into Honest (HON; n = 37) or Probable Cognitive Feigning (PCF; n = 53) groups based on results from the Victoria Symptom Validity Test, the Test of Memory Malingering, and the Digit Span subtest of the Wechsler Adult Intelligence Scale--3rd ed. The groups were generally comparable on demographic, background, and injury severity characteristics, although HON TBI participants were significantly more likely to have a documented loss of consciousness, whereas PCF participants were significantly more likely to be currently on disability. PCF participants scored significantly lower on many neuropsychological test, particularly of memory, as well as higher on most MMPI-2 clinical scales. The PCF group also had significantly higher scores on multiple indices of feigning of psychiatric symptoms. Results from the Letter Memory Test (LMT) were significantly lower for the PCF group, and using the recommended cutting score, specificity was .984, whereas sensitivity was .640, suggesting adequate performance on cross-validation.     

Rates of Below-Chance Performance in Forced-Choice Symptom Validity Tests

The rates of significantly below-chance results on three neuropsychological symptom validity tests (SVTs) including the Portland Digit Recognition Test (PDRT), Test of Memory Malingering (TOMM), and Word Memory Test (WMT) were compared in a private practice forensic sample of 1032 examinees with alleged mild traumatic brain injury, moderate to severe traumatic brain injury, alleged toxic exposure, and reported chronic pain. The PDRT and WMT were equivalent to one another in the rates of below-chance results, with both yielding more frequent below-chance results than the TOMM. Seemingly more difficult sections of the PDRT and WMT had higher yields than seemingly easier sections. Multiple SVTs were more likely to yield below-chance results than a single test, supporting the use of multiple SVTs in forensic neuropsychological evaluations.     

Manganese exposure: neuropsychological and neurological symptoms and effects in welders

Manganese exposure reportedly may have an adverse effect on CNS function and mood. Sixty-two welders with clinical histories of exposure to manganese were compared to 46 matched regional controls chosen at random from a telephone directory. The following tests were given: Wechsler Adult Intelligence Scale (WAIS-III), Wechsler Memory Scale (WMS-III), Boston Naming, WRAT-3, Cancellation H, Trail Making Tests A and B, Auditory Consonant Trigrams, Stroop, Rey-Osterreith, Animal Naming, Controlled Oral Word Association (COWAT), Test of Memory Malingering, Rey 15-item, Fingertapping, Grooved Pegboard, Dynamometer, Visual Attention Test, Lanthony d-15 Color Vision, Vistech Contrast Sensitivity, and Schirmer strips. The controls were administered a shorter battery of tests and the Rey-Osterreith, Animal Naming and some of the subtests of the WAIS-III, WMS-III were not administered. Mood tests, given to both groups, included the Symptom Checklist-40, Symptom Checklist-90-R, Profile of Mood Scale, Beck Depression Inventory II, and Beck Anxiety Inventory. Forty-seven welders and 42 controls were retained for statistical analysis after appropriate exclusions. Results showed a high rate of symptom prevalence and pronounced deficits in motor skills, visuomotor tracking speed and information processing, working memory, verbal skills (COWAT), delayed memory, and visuospatial skills. Neurological examinations compared to neuropsychological test results suggest that neuropsychologists obtain significantly more mood symptoms overall. Odds ratios indicate highly elevated risk for neuropsychological and neurological symptomatology of manganism. Mood disturbances including anxiety, depression, confusion, and impaired vision showed very high odds ratios. Neurological exams and neuropsychological tests exhibit complementarity and differences, though neuropsychological methods may be more sensitive in detecting early signs of manganism. The present study corroborates the findings of our previous study in another group of welders.     

Utility of the trail making test in the assessment of malingering in a sample of mild traumatic brain injury litigants

The Trail Making Test (TMT) is one of the most commonly administered tests in neuropsychological assessments. It has been shown to be a valid indicator of brain damage due to traumatic brain injury (TBI), as well as a number of other neuropathological conditions. TMT error and ratio scores have been suggested as possible markers of malingering. The present study examined the utility of various TMT scores as malingering measures in 94 TBI litigants. Litigants were divided into those suspected of (n = 27) and those not suspected of malingering (n = 67) based on scores obtained on the Test of Memory Malingering and/or the Rey 15-Item Test. TMT errors did not discriminate between suspected and nonsuspected malingerers; however, the overall level of performance on the TMT was suppressed in suspected malingerers. The TMT ratio score was significantly lower in litigants suspected of malingering, although the clinical utility of this ratio is minimal. Results of the present study suggest using caution when interpreting TMT scores as markers of malingering in TBI litigants.     

Distinguishing between neuropsychological malingering and exaggerated psychiatric symptoms in a neuropsychological setting

It is unclear whether symptom validity test (SVT) failure in neuropsychological and psychiatric domains overlaps. Records of 105 patients referred for neuropsychological evaluation, who completed the Test of Memory Malingering (TOMM), Reliable Digit Span (RDS), and Millon Clinical Multiaxial Inventory-III (MCMI-III), were examined. TOMM and RDS scores were uncorrelated with MCMI-III symptom validity indices and factor analysis revealed two distinct factors for neuropsychological and psychiatric SVTs. Only 3.5% of the sample failed SVTs in both domains, 22.6% solely failed the neuropsychological SVT, and 6.1% solely failed the psychiatric SVT. The results support a dissociation between neuropsychological malingering and exaggeration of psychiatric symptoms in a neuropsychological setting.     

Distinguishing between Neuropsychological Malingering and Exaggerated Psychiatric Symptoms in a Neuropsychological Setting

It is unclear whether symptom validity test (SVT) failure in neuropsychological and psychiatric domains overlaps. Records of 105 patients referred for neuropsychological evaluation, who completed the Test of Memory Malingering (TOMM), Reliable Digit Span (RDS), and Millon Clinical Multiaxial Inventory–III (MCMI–III), were examined. TOMM and RDS scores were uncorrelated with MCMI–III symptom validity indices and factor analysis revealed two distinct factors for neuropsychological and psychiatric SVTs. Only 3.5% of the sample failed SVTs in both domains, 22.6% solely failed the neuropsychological SVT, and 6.1% solely failed the psychiatric SVT. The results support a dissociation between neuropsychological malingering and exaggeration of psychiatric symptoms in a neuropsychological setting.     

The influence of white matter lesions on neuropsychological functioning in demented and non-demented 85-year-olds

White matter lesions on computed tomography of the head were studied in relation to neuropsychological functioning in subjects from a representative sample of non-demented ( n = 134) and demented ( n = 98) 85-year-olds. Non-demented subjects with white matter lesions ( n = 46) scored significantly lower in tests of verbal ability (Synonyms), spatial ability (Block Design, Clock Test), perceptual speed (Identical forms), secondary memory (Thurstone Picture Memory), basic arithmetic (Coin Test) and the global cognitive screening test Mini-Mental State Examination than non-demented subjects without white matter lesions ( n = 88). Demented subjects with white matter lesions ( n = 67) scored significantly lower in tests of spatial ability (Block Design and Clock Test) and secondary memory (free recall in the MIR memory test, Ten-word memory test I and II) and in the Mini-Mental State Examination than demented subjects without white matter lesions ( n = 31). It is concluded that white matter lesions contribute to cognitive decline in both non-demented and demented elderly subjects.     

Specific cognitive deficits are common in children with Duchenne muscular dystrophy

A neuropsychological assessment was conducted to study cognition, with emphasis on memory, information processing/learning ability, and executive functions in boys with Duchenne muscular dystrophy (DMD). A group of 20 boys with DMD, aged 7 to 14 years (mean age 9 years 5 months, SD 2 years 2 months), was contrasted with 17 normally developing age-matched comparison individuals, using specific neuropsychological tests (Block Span, Digit Span, Story Recall, Rey Auditory Verbal Learning Test, Rey Complex Figure Test, Spatial Learning Test, Verbal Fluency, Trail Making Test, Tower of London, Memory for Faces, and Raven's Coloured Progressive Matrices). The DMD group performed significantly worse on all aspects of memory, learning, and executive functions. There was no significant difference in general intellectual ability between the two groups. Analyses of group differences indicate that problems in short-term memory are the most apparent, suggesting specific cognitive deficits. The differences between the groups were similar for both verbal-auditory and visuospatial tests, thus contradicting the idea that cognitive deficits are related to type of stimulus presented. It is concluded from this study that short-term memory deficits might play a critical role in the cognitive impairment and intellectual development seen in those with DMD.     

Neuropsychological test performance of successful brain injury simulators

This study provided an examination of the performance characteristics of successful brain injury simulators (SBIS). Coached (n = 56) and uncoached (n = 35) brain injury simulators received instructions to fake cognitive impairment; controls were asked to do their best. The Test of Memory Malingering (TOMM) was administered along with standard neuropsychological measures (e.g., Wisconsin Card Sorting Test). The TOMM identified 80% of uncoached and 60% of coached brain injury simulators. SBIS were participants from the brain injury simulation groups whose TOMM performance indicated adequate effort. A total of 32% of all brain injury simulators scored above the TOMM cutoff scores for adequate effort (the SBIS group). Significantly more coached than uncoached participants composed the SBIS group (76% vs. 24%, respectively). SBIS performed significantly worse than controls and significantly better than unsuccessful brain injury simulators on select standard neuropsychological measures. The SBIS scores were lowered compared to controls; in some instances this lowered performance was at a clinically relevant level.     

A controlled study of neuropsychological deficits in acute spinal cord injury patients

According to a number of studies, between 40% and 60% of acute traumatic spinal cord injury (SCI) patients demonstrate cognitive dysfunction resulting from various forms of cerebral damage, including concurrent or premorbid closed head injury, chronic alcohol or substance abuse, and other causes. However, applicability of findings from these reports has been limited due to the use of inadequate neuropsychological testing techniques and the lack of control data. In a collaborative investigation, 81 acute SCI patients and 61 non-injured control subjects between 18 and 55 years of age completed a comprehensive motor-free neuropsychological test battery, including: Halstead Category Test (HCT), Vocabulary Subtest (VOCAB) of the Wechsler Adult Intelligence Scale - Revised; Mental Control (MC) Subtest, and Initial and Recall trials of Logical Memory (LM) and Paired Associates (PA) Subtests of the Wechsler Memory Scale; and the 8 trials of the Rey Auditory Verbal Learning Test (RAVLT). Percentages of retained information on the LM and PA were also calculated. Impairment levels for each test were defined as values which exceeded two standard deviations (one-tailed) from the control mean. Based on this definition, the prevalence of neuropsychological abnormality on each test ranged between 10% and 40%. Mean performance levels of patients were significantly more impaired than those of control subjects for all tests except for the Interference trial of the RAVLT and for the percentages of retained information on the LM and PA subtests. Comparison of test results of SCI patients with those of control subjects demonstrates that poor attention span and limited initial learning ability are frequent problems among SCI patients. Other common neuropsychological deficits among these patients include poor concentration ability, impaired memory function, and altered problem solving ability. These deficits may interfere with rehabilitation following SCI.     

Neuropsychological impairment in Wilson's disease

To examine the neuropsychological deficits of patients with Wilson's disease (WD), 19 neurologically impaired patients with WD were administered the Wechsler Adult Intelligence Scale (revised), Wechsler Memory Scale, Dementia Rating Scale, Wisconsin Card Sorting Test, Boston Naming Test, Trail Making Test, and Animal Naming Test. Their test scores were compared with those of 12 neurologically asymptomatic patients with WD and 15 normal controls. The neurologically impaired patients scored lower than did the control group on the Performance IQ, Full-Scale IQ, Dementia Rating Scale, and Trail Making Test, and they scored lower on the Wechsler Memory Scale than did both the asymptomatic and control groups. The major areas of deficit for the neurologically impaired WD group were in motor and memory functioning. Computed tomographic and neurologic examinations of the neurologically impaired patients with WD generally reflected abnormalities of the basal ganglia.     

PTSD and Cognitive Functioning: Importance of Including Performance Validity Testing

Many studies have observed an association between post-traumatic stress disorder (PTSD) and cognitive deficits across several domains including memory, attention, and executive functioning. The inclusion of response bias measures in these studies, however, remains largely unaddressed. The purpose of this study was to identify possible cognitive impairments correlated with PTSD in returning OEF/OIF/OND veterans after excluding individuals failing a well-validated performance validity test. Participants included 126 men and 8 women with a history of mild traumatic brain injury (TBI) referred for a comprehensive neuropsychological evaluation as part of a consortium of five Veterans Affairs hospitals. The PTSD CheckList (PCL) and Word Memory Test (WMT) were used to establish symptoms of PTSD and invalid performance, respectively. Groups were categorized as follows: Control (PCL < 50, pass WMT), PTSD-pass (PCL ≥ 50, pass WMT), and PTSD-fail (PCL ≥ 50, fail WMT). As hypothesized, failure on the WMT was associated with significantly poorer performance on almost all cognitive tests administered; however, no significant differences were detected between individuals with and without PTSD symptoms after separating out veterans failing the WMT. These findings highlight the importance of assessing respondent validity in future research examining cognitive functioning in psychiatric illness and warrant further consideration of prior studies reporting PTSD-associated cognitive deficits.     

Neuropsychological function in subjects with psychotic and affective disorders. Relationship to diagnostic category and duration of illness.

OBJECTIVE: To explore the links between neuropsychological performance, diagnostic category and duration of illness in subjects with psychotic and affective disorders. METHODS: Memory and executive abilities were tested in consecutively admitted patients with schizophrenia (N = 20), other non-schizophrenic psychotic disorders (N = 29), bipolar disorder (N = 33) and major depression (N = 19). RESULTS: Subjects with schizophrenia had poorer global memory performances than subjects with major depression, and poorer delayed verbal memory abilities than those from the other three diagnostic groups. Executive abilities explored by the Stroop test and the Wisconsin Card Sorting Test did not differ between diagnostic groups. Neuropsychological performances were not influenced by previous duration of illness. CONCLUSION: Memory deficits are the most discriminatory cognitive features between subjects with schizophrenia and those with other psychotic or mood disorders. The fact that cognitive deficits are static whatever the diagnostic group indirectly suggests that they may have a neurodevelopmental origin in subjects with schizophrenia, but perhaps also in subjects with other psychotic and mood disorders.     

Known-Groups Cross-Validation of the Letter Memory Test in a Compensation-Seeking Mixed Neurologic Sample

Compensation-seeking neuropsychological evaluees were classified into Honest (HON; n = 37) or Probable Cognitive Feigning (PCF; n = 53) groups based on results from the Victoria Symptom Validity Test, the Test of Memory Malingering, and the Digit Span subtest of the Wechsler Adult Intelligence Scale—3rd ed. The groups were generally comparable on demographic, background, and injury severity characteristics, although HON TBI participants were significantly more likely to have a documented loss of consciousness, whereas PCF participants were significantly more likely to be currently on disability. PCF participants scored significantly lower on many neuropsychological test, particularly of memory, as well as higher on most MMPI-2 clinical scales. The PCF group also had significantly higher scores on multiple indices of feigning of psychiatric symptoms. Results from the Letter Memory Test (LMT) were significantly lower for the PCF group, and using the recommended cutting score, specificity was .984, whereas sensitivity was .640, suggesting adequate performance on cross-validation.     

Use of Trial 1 of the Test of Memory Malingering (TOMM) as a screening measure of effort: suggested discontinuation rules

Trial 1 of the Test of Memory Malingering (TOMM) has been suggested as a screening tool, with several possible cut-off scores proposed. The purpose of the present study was to replicate the utility of previously suggested cut-off scores and to characterize neuropsychological profiles of persons who "pass" the TOMM but obtain Trial 1 scores < 45 and of persons with cognitive disorders. A total of 229 veterans were administered the TOMM as part of a neuropsychological evaluation. Trial 1 scores ≥ 41 and ≤ 25 showed good utility as discontinuation scores for adequate and poor effort, respectively, beyond which administration of additional trials were unnecessary. Findings suggest better Trial 1 performance is significantly related to better speeded mental flexibility and memory.     

Cognitive functioning related to quality of life in schizophrenia

The present study compared the cognitive function of patients with schizophrenia to that of healthy subjects, and investigated the relationships between cognitive function and quality of life (QOL). Participants consisted of 53 patients meeting DSM-IV criteria for schizophrenia and 31 normal controls. All participants completed a neuropsychological test battery assessing executive function, verbal memory, and social knowledge. QOL was rated using the Schizophrenia Quality of Life Scale. Patients with schizophrenia showed lower performance across various cognitive measures of memory, including the Sentence Memory Test, the Verbal Learning Test, and the Script Test, as well as the Rule Shift Cards Test of executive function. Multiple regression analyses were used to evaluate the neuropsychological measures and clinical symptoms to predict QOL. The QOL total score, the social initiative score or the empathy score were significantly predicted by the Script or/and the Sentence Memory. Neuropsychological functioning was unrelated to most QOL scores in the presence of clinical symptoms, while ability of empathy in the QOL was predicted by performance of the Sentence Memory Test. These results demonstrated patients with schizophrenia have deficits in executive function, memory and learning, and social knowledge, and that social knowledge and memory are related to QOL. Thus, in patients with schizophrenia, deficits in social knowledge appear to be associated with current QOL in general, and specifically with the capacity for empathy and social initiative.     

Use of Trial 1 of the Test of Memory Malingering (TOMM) as a Screening Measure of Effort: Suggested Discontinuation Rules

Trial 1 of the Test of Memory Malingering (TOMM) has been suggested as a screening tool, with several possible cut-off scores proposed. The purpose of the present study was to replicate the utility of previously suggested cut-off scores and to characterize neuropsychological profiles of persons who “pass” the TOMM but obtain Trial 1 scores <45 and of persons with cognitive disorders. A total of 229 veterans were administered the TOMM as part of a neuropsychological evaluation. Trial 1 scores ≥41 and ≤25 showed good utility as discontinuation scores for adequate and poor effort, respectively, beyond which administration of additional trials were unnecessary. Findings suggest better Trial 1 performance is significantly related to better speeded mental flexibility and memory.     

On the limits of effort testing: symptom validity tests and severity of neurocognitive symptoms in nonlitigant patients

Modern symptom validity tests (SVTs) use empirical cutoffs for decision making. However, limits to the applicability of these cutoffs may arise when severe cognitive symptoms are present. The purpose of the studies presented here was to explore these limits of applicability. In Experiment 1, a group of 24 bona fide neurological patients without clinically obvious cognitive symptoms was compared to a group of 24 patients with rather severe symptoms. A comprehensive test battery was employed, which included four SVTs (the Test of Memory Malingering, TOMM, the Word Memory Test, WMT, the Bremer Symptomvalidierung, BSV, and the Amsterdam Short-Term Memory Test, ASTM). In Experiment 2, a group of 20 patients with mild Alzheimer's disease was compared to 14 healthy controls. Results of both studies showed that cognitive impairment may significantly interfere with SVT performance. Correlation analyses revealed dissimilar relationships between SVTs and neuropsychological test measures. Whereas TOMM and WMT correlated mainly with tests of declarative memory, the BSV correlated with tests of attention, and ASTM correlated with tests of working memory. Intercorrelations between symptom validity measures were relatively low. The published cutoffs of the TOMM would be suitable for estimating effort in patients with Mini-Mental State Examination scores of 24 or above. More research will be necessary to investigate how performance in SVTs is related to cognitive functioning in populations of severely impaired patients.     

Mild cognitive impairment: a risk indicator of later dementia,or a preclinical phase of the disease?

OBJECTIVES: The proposals for classifying the transitional range between normal, ageing-associated cognitive dysfunctions and those suggestive of evolution towards dementia do not clarify whether the profiles are risk indicators of later cognitive impairment or represent preclinical phases of dementia. METHODS: Retrospective study of the baseline neuropsychological performance of ten subjects with subjective complaints of memory loss which evolved to dementia within 2 years and who meet clinical and neurological diagnosis for Probable Alzheimer's Disease (Progression group). They were compared with 34 normal subjects (Normative group), 33 patients with subjective complaints of memory who in 2 year did not evolve towards dementia and presented a stable profile (Stable group), and 47 Alzheimer's patients (Alzheimer group). A broad neuropsychological battery was administered to assess a range of cognitive functions. RESULTS: The Progression group presented a globally poor baseline neuropsychological performance, except in Working Memory, with clear deficits in Episodic Memory and Visual Memory. In the logistic regression analysis, Delayed Verbal Memory was significant as prognostic value for 80 . 5% of cases. CONCLUSION: Deficit on Episodic and Visual Memory at least 1.5 SD below T = 50 are preclinical manifestations of dementia in subjects with complain of memory loss. The use of broad neuropsychological batteries and the quantitative assessment of deficits is essential to identify and predict the risk of dementia.