Malingering detection with the Wisconsin Card Sorting Test in mild traumatic brain injury.

This study evaluates the ability of several Wisconsin Card Sorting Test (WCST; Psychological Assessment Resources, 1990) variables to detect malingering in mild traumatic brain injury (TBI). The sample consisted of 373 TBI patients and 766 general clinical patients. Classification accuracy for seven indicators is reported across a range of injury severity and scores levels. Overall, most WCST scores were ineffective in discriminating malingering from non-malingering mild TBI patients. Failure-to-Maintain-Set, the Suhr & Boyer formula, and the King et al. formula detected about 30% of malingerers at cutoffs associated with a false positive error rate of < or =11%. The clinical interpretation and use of these indicators are discussed.

Classification accuracy of MMPI-2 validity scales in the detection of pain-related malingering: a known-groups study.

The purpose of this study was to determine the accuracy of Minnesota Multiphasic Personality Inventory 2nd edition (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) validity indicators in the detection of malingering in clinical patients with chronic pain using a hybrid clinical-known groups/simulator design. The sample consisted of patients without financial incentive (n = 23), nonmalingering patients with financial incentive (n = 34), patients definitively determined to be malingering based on published criteria ( n = 32), and college students asked to simulate pain-related disability (n = 26). The MMPI-2 validity scales differentiated malingerers from nonmalingerers with a high degree of accuracy. Hypochondriasis and Hysteria were also effective. For all variables except Scale L, more extreme scores were associated with higher specificity. This study demonstrates that the MMPI-2 is capable of differentiating intentional exaggeration from the effects on symptom report of chronic pain, genuine psychological disturbance, and concurrent stress associated with pursuing a claim in a medico-legal context.

Classification accuracy of the Portland digit recognition test in persons claiming exposure to environmental and industrial toxins.

The classification accuracy of the Portland digit recognition test (PDRT) in detecting cognitive malingering was studied in patients claiming cognitive deficits due to exposure to environmental or industrial toxins. Twenty-nine patients alleging toxic exposure and who met Slick et al. [Slick, D. J., Sherman, E. M. S., & Iverson, G. L. (1999). Diagnostic criteria for malingering neurocognitive dysfunction: Proposed standards for clinical practice and research. The Clinical Neuropsychologist, 13, 545-561] criteria for malingered neurocognitive dysfunction were compared to 14 toxic exposure patients negative for evidence of malingering. The published cutoffs were associated with a false positive error rate of 0% and sensitivity of more than 50%. When criterion for a PDRT failure was a positive PDRT finding on more than one section, the FP rate remained 0% while sensitivity improved to about 70%. The results indicate that a failed PDRT is an indication of malingering and not the neurological effect of a toxic substance or some other clinical phenomenon. The PDRT can be used with confidence as an indicator of negative response bias in cases of alleged exposure to neurotoxic substances.

Malingering in toxic exposure: classification accuracy of reliable digit span and WAIS-III Digit Span scaled scores.

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.

Sensitivity and specificity of MMPI-2 validity scales and indicators to malingered neurocognitive dysfunction in traumatic brain injury.

The present study used a known-groups design to determine the classification accuracy of 10 MMPI-2 validity scales and indicators in the detection of cognitive malingering in traumatic brain injury. Participants were 259 traumatic brain injury and 133 general clinical patients seen for neuropsychological evaluation. The TBI patients were subdivided into groups based on a comprehensive examination of effort following Slick, Sherman, and Iverson's (1999) criteria. More extreme scores demonstrated excellent specificity; often impressive sensitivity was seen even while maintaining a low false positive error rate. Specificity was good even in stroke, memory disorder, and psychiatric patients without incentive. The results of this study are presented in frequency tables that can be easily referenced in clinical practice.

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.

Classification accuracy of the Test of Memory Malingering in persons reporting exposure to environmental and industrial toxins: Results of a known-groups analysis.

This study used a known-groups design to examine the classification accuracy of the Test of Memory Malingering in detecting cognitive malingering in patients claiming cognitive deficits due to exposure to environmental and industrial toxins. Thirty-three patients who met Slick et al. criteria for Malingered Neurocognitive Dysfunction were compared to 17 toxic exposure patients negative for evidence of malingering, 14 TBI patients and 22 memory disorder patients, both groups without incentive. The original cutoffs (<45) for Trial 2 and Retention demonstrated perfect specificity (0% false positive error rate) and impressive sensitivity (>50%). These findings indicate the TOMM can be used with confidence as an indicator of negative response bias in cases of cognitive deficits attributed to exposure to alleged neurotoxic substances.

Pain, malingering, and performance on the WAIS-III Processing Speed Index.

Pain patients often report cognitive symptoms and many will include them in their claims of disability. The Processing Speed Index (PSI) of the WAIS-III was investigated as one aspect of cognitive functioning in six groups. Slight impairment was found for PSI and Digit Symbol subtest performance, but not for Symbol Search, in a Laboratory-induced Pain group and a Clinical Pain group. The lowest scores were found in a Simulator group instructed to fake cognitive impairment and a Clinical Pain group diagnosed as Malingering. Results suggest that PSI scores are only slightly reduced by laboratory-induced pain or chronic pain, and that unexpectedly low scores in the absence of significant/documented brain dysfunction suggest poor effort or deliberate misrepresentation.

Pain, malingering and the WAIS-III Working Memory Index.

BACKGROUND CONTEXT: Pain patients often report cognitive symptoms, and many will include them in their claims of disability. There is empirical evidence that patients with pain do experience problems on attention-demanding cognitive tasks, but the results are mixed and the potential impact of exaggeration in the context of pain-related litigation has not been addressed. PURPOSE: 1) Examine the impact of pain and malingering on attention; 2) determine if the Working Memory Index (WMI) of the Wechsler Adult Intelligence Scale-3 (WAIS-III) can reliably detect malingering. STUDY DESIGN/SETTING: Study 1: simulator design; Study 2: clinical known-groups design. PATIENT SAMPLE: Study 1 used healthy college students; Study 2 used chronic pain patients and neurological patients. OUTCOME MEASURES: The WMI and its constituent subtests. METHODS: Study 1: College students were administered the WMI under three conditions: standard administration, with cold-pressor induced pain, or with instructions to simulate impairment due to pain. Study 2: Known-groups design in which the WMI was examined in non-malingering and definite malingering chronic pain patients, non-malingering moderate-severe traumatic brain injury, and memory disorder patients seen for routine psychological evaluation. Malingering was operationalized using published criteria. RESULTS: There were no group differences in WMI or its subtests among non-malingering groups, but some individual clinical patients with pain did score at a level suggestive of attentional impairment. The lowest scores were found in the simulated malingering college students and definite malingering clinical pain groups, in which about half scored worse than 95% of the non-malingering clinical patients. CONCLUSIONS: This study demonstrated that even when controlling for exaggeration some pain patients do exhibit problems with attentional function. However, significant impairment in WMI performance (eg, index score

WAIS digit span-based indicators of malingered neurocognitive dysfunction: classification accuracy in traumatic brain injury.

The present study determined specificity and sensitivity to malingered neurocognitive dysfunction (MND) in traumatic brain injury (TBI) for several Wechsler Adult Intelligence Scale (WAIS) Digit Span scores. TBI patients (n = 344) were categorized into one of five groups: no incentive, incentive only, suspect, probable MND, and definite MND. Performance of 1,063 nonincentive patients (e.g., cerebrovascular accident, memory disorder) was also examined. Digit Span scores included reliable digit span, maximum span forward both trials correct, maximum span forward, combined maximum forward and backward span, Digit Span scaled score, maximum span backward both trials correct, and maximum span backward. In TBI, sensitivity to MND ranged from 15% to greater than 30% at specificities of 92% to 98%. Patient groups with documented brain pathology had higher false-positive error rates. These results replicate previous known-groups malingering studies and provide valuable data supporting the WAIS Digit Span scores in detection and diagnosis of malingering.

Detection of feigned tactile sensory loss using a forced-choice test of tactile discrimination and other measures of tactile sensation.

OBJECTIVE: Intentional exaggeration of disability is a risk in work injuries but is hard to reliably detect clinically. This study examined the accuracy of tactile sensory threshold and forced-choice discrimination measures in detecting feigned sensory loss. METHODS: Participants (n = 80) were randomly assigned to one of four sensory loss groups: (1) none; (2) partial; (3) full; or (4) feigned. Sensory data were collected for the upper extremities. RESULTS: Tactile thresholds greater than 0.5 g, discriminability less than 0.50, or forced-choice scores less than 90% were associated with a very low probability of false-positive errors. CONCLUSIONS: Below-chance scores are definitive evidence that the sensory loss is intentionally feigned. Scores beyond cut-offs should raise the clinician's suspicion of malingering if there is no physical basis for sensory loss.

Sensitivity and specificity of reliable digit span in malingered pain-related disability.

The reliable digit span (RDS) performance of chronic pain patients with unambiguous spinal injuries and no evidence of exaggeration or response bias (n = 53) was compared to that of chronic pain patients meeting criteria for definite malingered neurocognitive dysfunction (n = 35), and a group of nonmalingering moderate-severe traumatic brain injury (TBI) patients (n = 69). The results demonstrated that scores of 7 or lower were associated with high specificity (> .90) and sensitivity (up to .60) even when moderate to severe TBI are included. Multiple studies have demonstrated that RDS scores of 7 or lower rarely occur in TBI and pain patients who are not intentionally performing poorly on cognitive testing. This study supports the use of the RDS in detecting response bias in neuropsychological patients complaining of pain as well as in the assessment of pain-related cognitive impairment in patients whose primary complaint is pain.