Performance Validity and Neuropsychological Outcomes in Litigants and Disability Claimants

Examining the cross-cultural validity of the test of memory malingering and the Rey 15-item test

OBJECTIVE

This study was designed to investigate the cross-cultural validity of two freestanding performance validity tests (PVTs), the Test of Memory Malingering - Trial 1 (TOMM-1) and the Rey Fifteen Item Test (Rey-15) in Romanian-speaking patients.

METHODS

The TOMM-1 and Rey-15 free recall (FR) and the combination score incorporating the recognition trial (COMB) were administered to a mixed clinical sample of 61 adults referred for cognitive evaluation, 24 of whom had external incentives to appear impaired. Average scores on PVTs were compared between the two groups. Classification accuracies were computed using one PVT against another.

RESULTS

Patients with identifiable external incentives to appear impaired produced significantly lower scores and more errors on validity indicators. The largest effect sizes emerged on TOMM-1 (Cohen's d = 1.00-1.19). TOMM-1 was a significant predictor of the Rey-15 COMB ≤20 (AUC = .80; .38 sensitivity; .89 specificity at a cutoff of ≤39). Similarly, both Rey-15 indicators were significant predictors of TOMM-1 at ≤39 as the criterion (AUCs = .73-.76; .33 sensitivity; .89-.90 specificity).

CONCLUSION

Results offer a proof of concept for the cross-cultural validity of the TOMM-1 and Rey-15 in a Romanian clinical sample.

Ability of the Wisconsin Card-Sorting Test-64 as an embedded measure to identify noncredible neurocognitive performance in mild traumatic brain injury litigants

OBJECTIVE

To investigate the ability of selective measures on the Wisconsin Card Sorting Test-64 (WCST-64) to predict noncredible neurocognitive dysfunction in a large sample of mild traumatic brain injury (mTBI) litigants.

METHOD

Participants included 114 adults who underwent a comprehensive neuropsychological examination. Criterion groups were formed based upon their performance on stand-alone measures of cognitive performance validity (PVT).

RESULTS

Participants failing PVTs performed worse across all WCST-64 dependent variables of interest compared to participants who passed PVTs. Receiver operating curve analysis revealed that only categories completed was a significant predictors of PVT status. Multivariate logistic regression did not add to classification accuracy.

CONCLUSION

Consideration of noncredible executive functioning may be warranted in mild traumatic brain injury (mTBI) litigants who complete ≤ 1 category on the WCST-64.

Commonality in Abnormality: "Abnormal" Neuropsychological Scores Are Common in Baseline Testing of Youth Athletes

OBJECTIVE

Although research shows that abnormal scores are common in adults, fewer studies examine the frequency of abnormal scores within children. The present study assessed how specific tests, cognitive domains, and patient factors affect the likelihood of abnormally low scores among healthy youth athletes.

METHODS

Youth athletes (n = 85, Mage = 11.72, SD = 2.23) completed a comprehensive neuropsychological battery (N = 23 tests) during baseline testing for a sport-related concussion clinical research program. "Abnormal" scores were defined using cutoffs at 1, 1.5, and 2 standard deviations (SDs) below the population mean. Univariate and multivariate Poisson regression models examined abnormal test scores as a function of age, sex, ethnicity, and Full-Scale Intelligence Quotient (FSIQ).

RESULTS

Using cutoffs of 1, 1.5, and 2 SDs, the percent of healthy participants with at least one abnormal test score was 61.2, 36.5, and 22.4%, respectively, indicating a high proportion of healthy participants with abnormal scores and low specificity for tests using these cutoffs. In univariate Poisson regression analyses, FSIQ and abnormal score were negatively correlated (p < .001), wherein lower FSIQ was associated with more abnormal scores. In multivariate regression analyses, lower performance on executive function, memory, and processing speed tests was significantly associated with an increased frequency of abnormal scores.

CONCLUSIONS

Abnormally low scores in healthy youth occur frequently and do not necessarily represent functional deficits. Cutoffs of 2 SDs should be considered for many tests to increase specificity and reduce the risk of false positive errors that could lead to negative clinical outcomes.

Examining the Cognitive Proficiency Index in rehabilitation patients

This study examined the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) Cognitive Proficiency Index (CPI) in relation to other WAIS-IV indices, overall test battery mean (OTBM), and impairment (IMP) in an outpatient rehabilitation setting. Participants (N = 329) were 35% female and 88% Caucasian with average age and education of 42.9 (SD = 13.5) and 13.6 (SD = 2.4) years, respectively. Participants were grouped by diagnosis and validity: traumatic brain injury (TBI; n = 176; 39% mild), cerebrovascular accident (CVA; n = 52), other neurologic and psychiatric conditions (OTH; n = 49), and questionable performance validity (QPV; n = 52). OTBM was calculated from non-WAIS-IV tests; IMP was dichotomously defined as four or more non-WAIS-IV scores below cutoff (≤35 T). Significant group differences were observed on CPI, WAIS-IV indices, OTBM, and IMP. CPI significantly contributed (β = .51) to a linear regression model predicting OTBM (R² = .63) with education and GAI as covariates. A logistic regression model with IMP as the outcome and education, GAI, and CPI as predictors correctly classified 80% of cases with area under the curve of .86. A previously identified cutoff (CPI < 84) correctly classified 65-78% of clinical groups categorized by IMP. A novel cutoff (CPI ≤ 80) differentiated clinical participants with history of mild TBI from the QPV group with sensitivity of 44.2% and specificity of 89.7%. CPI showed incremental validity in predicting OTBM and IMP and warrants further study as a useful clinical addition to other WAIS-IV indices.

Elevated rates of memory impairment in military service-members and veterans with posttraumatic stress disorder

INTRODUCTION

Studies investigating the neurocognitive effects of posttraumatic stress disorder (PTSD) routinely find "deficits" in various cognitive domains. However, the rate of cognitive impairment in individuals with PTSD remains unclear, as studies have focused on null hypothesis testing (NHT) and inferring patterns of impairment rather than empirically determining the rate of cognitive impairment in this sample.

METHOD

This study examined rates of cognitive impairment using a domain-specific approach in non-treatment-seeking Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn service members and veterans with (n = 92) and without (n = 79) PTSD and without substance abuse/dependence who passed a performance validity measure and were matched on age, education, estimated IQ, and ethnicity. Chi-square analyses were used to compare the rate of cognitive impairment across groups based on normative scores using three cutoffs (-1, -1.5, and -2 SDs). NHT was also used to compare performances across groups.

RESULTS

Individuals with PTSD showed higher rates of impairment in memory (-1-SD cutoff) than controls, but equivalent rates of impairment in attention, processing speed, and executive functioning; no significant differences were found on NHT. Impairment in any domain was also more prevalent in PTSD (-1-, -1.5-, and -2-SD cutoffs). No differences were found on NHT or rates of impairment in individuals with PTSD with (n = 34) and without (n = 58) depression.

CONCLUSIONS

Patients with PTSD were more likely to meet criteria for memory impairment and to show impairment in any domain than controls. Patients with PTSD and comorbid depression were no more likely to be impaired in any cognitive domain or to have lower scores on individual cognitive tasks than patients with PTSD alone. Clinicians noting cognitive impairment in individuals with PTSD should exercise caution before ascribing that impairment to another etiology if deficits are limited to memory.

Rates of Abnormally Low TOPF Word Reading Scores in Individuals Failing Versus Passing Performance Validity Testing

The present study examined the impact of performance validity test (PVT) failure on the Test of Premorbid Functioning (TOPF) in a sample of 252 neuropsychological patients. Word reading performance differed significantly according to PVT failure status, and number of PVTs failed accounted for 7.4% of the variance in word reading performance, even after controlling for education. Furthermore, individuals failing ≥2 PVTs were twice as likely as individuals passing all PVTs (33% vs. 16%) to have abnormally low obtained word reading scores relative to demographically predicted scores when using a normative base rate of 10% to define abnormality. When compared with standardization study clinical groups, those failing ≥2 PVTs were twice as likely as patients with moderate to severe traumatic brain injury and as likely as patients with Alzheimer’s dementia to obtain abnormally low TOPF word reading scores. Findings indicate that TOPF word reading based estimates of premorbid functioning should not be interpreted in individuals invalidating cognitive testing.

Magnetoencephalography Slow-Wave Detection in Patients with Mild Traumatic Brain Injury and Ongoing Symptoms Correlated with Long-Term Neuropsychological Outcome

Mild traumatic brain injury (mTBI) is common in the United States, accounting for as many as 75-80% of all TBIs. It is recognized as a significant public health concern, but there are ongoing controversies regarding the etiology of persistent symptoms post-mTBI. This constellation of nonspecific symptoms is referred to as postconcussive syndrome (PCS). The present study combined results from magnetoencephalography (MEG) and cognitive assessment to examine group differences and relationships between brain activity and cognitive performance in 31 military and civilian individuals with a history of mTBI+PCS and 33 matched healthy control subjects. An operator-free analysis was used for MEG data to increase reliability of the technique. Subjects completed a comprehensive neuropsychological assessment, and measures of abnormal slow-wave activity from MEG were collected. Results demonstrated significant group differences on measures of executive functioning and processing speed. In addition, significant correlations between slow-wave activity on MEG and patterns of cognitive functioning were found in cortical areas, consistent with cognitive impairments on exams. Results provide more objective evidence that there may be subtle changes to the neurobiological integrity of the brain that can be detected by MEG. Further, these findings suggest that these abnormalities are associated with cognitive outcomes and may account, at least in part, for long-term PCS in those who have sustained an mTBI.