Classification Accuracy of the Test of Memory Malingering in Traumatic Brain Injury: Results of a Known-Groups Analysis

The Clinical Utility of the Conners' Continuous Performance Test-II in Traumatic Brain Injury

OBJECTIVE

The Conners' Continuous Performance Test Second Edition (CPT-II) is a measure commonly used in persons with suspected attentional deficits. Our study examined the utility of the CPT-II as a measure of attention in adults with traumatic brain injury (TBI) of varying severity.

METHOD

As part of a larger investigation, several measures of cognitive functioning, including the CPT-II, were administered to 30 healthy control participants (HCP), 30 mild TBI participants (M-TBI), and 30 moderate to severe TBI participants (MS-TBI). Multivariate and correlational analyses compared group performances and examined convergent and divergent relationships between the CPT-II and various measures, including other tests of attention and neuropsychological function.

RESULTS

Group differences were found for four of six CPT-II variables, with the MS-TBI group exhibiting greater impairment, relative to M-TBI and HCP. In addition, the CPT-II commission and detectability variables were found to correlate significantly with TBI severity. The CPT-II variables also demonstrated correlations of varying magnitude between commonly used neuropsychological measures.

CONCLUSIONS

These findings support the utility of the CPT-II for assessing attentional abilities in persons with TBI of varying severity, particularly those with moderate to severe status. Moreover, the current study also demonstrates relationships that are consistent with convergent validity but inconsistent findings with regard to divergent validity. As a result, the CPT-II measures components of attention that is unique to other commonly used neuropsychological measures of attentive functioning. Further research examining CPT-II performance in TBI populations is recommended.

Malingering in Toxic Exposure

This study examined the sensitivity and false-positive error rate of reliable digit span (RDS) and the WAIS-III Digit Span (DS) scaled score in persons alleging toxic exposure and determined whether error rates differed from published rates in traumatic brain injury (TBI) and chronic pain (CP). Data were obtained from the files of 123 persons referred for neuropsychological evaluation related to alleged exposure to environmental and industrial substances. Malingering status was determined using the criteria of Slick, Sherman, and Iverson (1999). The sensitivity and specificity of RDS and DS in toxic exposure are consistent with those observed in TBI and CP. These findings support the use of these malingering indicators in cases of alleged toxic exposure and suggest that the classification accuracy data of indicators derived from studies of TBI patients may also be validly applied to cases of alleged toxic exposure.

Bridging the gap between neurocognitive processing theory and performance validity assessment among the cognitively impaired: a review and methodological approach

Bigler (2012) and Larrabee (2012) recently addressed the state of the science surrounding performance validity tests (PVTs) in a dialogue highlighting evidence for the valid and increased use of PVTs, but also for unresolved problems. Specifically, Bigler criticized the lack of guidance from neurocognitive processing theory in the PVT literature. For example, individual PVTs have applied the simultaneous forced-choice methodology using a variety of test characteristics (e.g., word vs. picture stimuli) with known neurocognitive processing implications (e.g., the "picture superiority effect"). However, the influence of such variations on classification accuracy has been inadequately evaluated, particularly among cognitively impaired individuals. The current review places the PVT literature in the context of neurocognitive processing theory, and identifies potential methodological factors to account for the significant variability we identified in classification accuracy across current PVTs. We subsequently evaluated the utility of a well-known cognitive manipulation to provide a Clinical Analogue Methodology (CAM), that is, to alter the PVT performance of healthy individuals to be similar to that of a cognitively impaired group. Initial support was found, suggesting the CAM may be useful alongside other approaches (analogue malingering methodology) for the systematic evaluation of PVTs, particularly the influence of specific neurocognitive processing components on performance.

Unreliable block span reveals simulated intellectual disability on the stanford-binet intelligence scales-fifth edition

Previously developed validity measures are largely lacking in their ability to accurately distinguish malingerers from individuals with genuine intellectual disabilities (ID). The purpose of the present study was to develop a validity index for the Stanford-Binet Intelligence Scales-Fifth Edition (SB-5) aimed at detecting malingered ID. Fifty-four college students were instructed to feign impairment consistent with mental retardation while completing the SB-5. Simulated malingerers performed significantly poorer on the Block Span task of the SB-5 than did individuals with genuine impairment. A Block Span Validity Index (BSVI) cutoff score of less than 10 showed perfect specificity by correctly identifying all persons with true ID and demonstrated 52% sensitivity in identifying persons feigning impairment. For the detection of malingered ID, the BSVI yielded favorable results, although more research is needed to validate the BSVI using a known-groups study design.

Lying in neuropsychology

The issue of lying occurs in neuropsychology especially when examinations are conducted in a forensic context. When a subject intentionally either presents non-existent deficits or exaggerates their severity to obtain financial or material compensation, this behaviour is termed malingering. Malingering is discussed in the general framework of lying in psychology, and the different procedures used by neuropsychologists to evidence a lack of collaboration at examination are briefly presented and discussed. When a lack of collaboration is observed, specific emphasis is placed on the difficulty in unambiguously establishing that this results from the patient's voluntary decision.

Efficacy of test of memory malingering Trial 1, Trial 2, the Retention Trial, and the Albany Consistency Index in a criterion group forensic neuropsychological sample

The Test of Memory Malingering is one of the most popular and heavily researched validity tests available for use in neuropsychological evaluations. Recent research has suggested, however, that the original indices and cutoffs may require modifications to increase sensitivity rates. Some of these modifications lack cross-validation and no study has examined all indices in a single sample. This study compares Trial 1, Trial 2, the Retention Trial, and the newly created Albany Consistency Index in a criterion group forensic neuropsychological sample. Findings lend support for the newly created indices and cutoff scores. Implications and cautionary statements are provided and discussed.

Prevalence of malingering in patients with chronic pain referred for psychologic evaluation in a medico-legal context

OBJECTIVE

To provide an empirical estimate of the prevalence of malingered disability in patients with chronic pain who have financial incentive to appear disabled.

DESIGN

Retrospective review of cases.

SETTING

A private neuropsychologic clinic in a southeastern metropolitan area.

PARTICIPANTS

Consecutive patients (N=508) referred for psychologic evaluation related to chronic pain over a 10-year period (1995-2005).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Prevalence of malingering was examined using 2 published clinical diagnostic systems (Malingered Pain-Related Disability and Malingered Neurocognitive Dysfunction) as well as statistical estimates based on well validated indicators of malingering.

RESULTS

The prevalence of malingering in patients with chronic pain with financial incentive is between 20% and 50% depending on the diagnostic system used and the statistical model's underlying assumptions. Some factors associated with the medico-legal context such as the jurisdiction of a workers' compensation claim or attorney representation were associated with slightly higher malingering rates.

CONCLUSIONS

Malingering is present in a sizable minority of patients with pain seen for potentially compensable injuries. However, not all excess pain-related disability is a result of malingering. It is important not to diagnose malingering reflexively on the basis of limited or unreliable findings. A diagnosis of malingering should be explicitly based on a formal diagnostic system.

Executive dysfunction in traumatic brain injury: the effects of injury severity and effort on the Wisconsin Card Sorting Test

This study examined the persistent effects of traumatic brain injury (TBI) on Wisconsin Card Sorting Test (WCST) performance. Since poor effort can contaminate results in populations with incentive to perform poorly, performance validity was explicitly assessed and controlled for using multiple well-validated cognitive malingering indicators. Participants were 109 patients with mild TBI and 67 patients with moderate-to-severe TBI seen for neuropsychological evaluation at least one year post injury. Patients with diffuse neurological impairment and healthy controls were included for comparison. Results suggested a dose-response effect of TBI severity on WCST performance in patients providing good effort; the mild TBI group did not differ from controls while increased levels of impairment were observed in the moderate-to-severe TBI group. Effort during testing had a larger impact on WCST performance than mild or moderate-to-severe TBI. Clinical implications of these findings are discussed.

Are the Original and Second Edition of the California Verbal Learning Test Equally Accurate in Detecting Malingering?

This two-part study sought to determine the equivalence of the California Verbal Learning Tests (CVLT-1 and CVLT-2) in the detection of malingering in traumatic brain injury (TBI) and chronic pain. Part 1 compared a variety of scores from the two versions in carefully matched patient groups. Part 2 used criterion groups (known-groups) methodology to examine the relative rates of false positive (FP) errors across the two versions. Participants were 442 TBI (CVLT-1 = 310; CVLT-2 = 132) and 378 chronic pain patients (CVLT-1 = 250; CVLT-2 = 128). Overall, the CVLT-2 was more difficult than the CVLT-1, with the chronic pain patients showing larger version effects than the TBI patients. The two versions of the CVLT were equally accurate in detecting malingering in TBI and chronic pain. However, they were not interchangeable. The use of CVLT-1 cutoffs with the CVLT-2 may result in an increased risk of FP error. Appropriate cutoff adjustment in clinical practice is recommended.

The Test Validation Summary

Common rates employed in classificatory testing are the true positive rate (TPR), false positive rate (FPR), positive predictive power (PPP), and negative predictive power (NPP). FPR and TPR are estimated from research samples representing populations to be distinguished by classificatory testing. PPP and NPP are used by clinicians to classify test takers into populations. PPP and NPP depend on the base rate (BR) of population members in the clinician's sample. The authors introduce the test validation summary (TVS) as a means to report within a single graph the FPR and TPR and the ranges of PPP and NPP across all potential sample BRs for any chosen cut score. The authors investigate how the TVS has other applications, including the estimation of local BR for the condition of interest and the estimation of standard errors for FPR and TPR when estimated across multiple independent validation studies of the classificatory test.

The prevalence of cognitive malingering in persons reporting exposure to occupational and environmental substances

OBJECTIVE

Directly estimate the prevalence of cognitive malingering in persons claiming exposure to occupational and environmental substances.

METHODS

Retrospective review of 128 neuropsychological cases with financial incentive. Estimates were based on two methods: (1) clinical identification using the Slick, Sherman and Iverson criteria for malingered neurocognitive dysfunction (MND), and (2) statistical modeling based on patient performance on several individual psychometric indicators of malingering.

RESULTS

The prevalence based on the clinical method was 40%. The statistically based estimates ranged from 30% to more than 45% depending on model parameters. Different incentive parameters may influence prevalence.

CONCLUSIONS

Cognitive malingering in toxic exposure is common and must be adequately addressed in the clinical neuropsychological assessment of toxic exposure and in research on its neurocognitive effects or findings will likely over-estimate the degree of cognitive impairment and related disability.