Justin B. Miller

Detection of Insufficient Effort Using the Advanced Clinical Solutions for the Wechsler Memory Scale, Fourth Edition

This study investigated the ability of the Wechsler Memory Scale-4th Edition (WMS-IV) and the Advanced Clinical Solutions (ACS) package including the new Word Choice test (WCT) to distinguish poor performance due to intentional response bias among simulators of traumatic brain injury (TBI) from poor performance due to actual TBI. Participants were 45 survivors of moderate to severe TBI and 39 healthy adult coached to simulate TBI. Logistic regression indicated that a five-variable model containing all the ACS variables and a single-variable model using only the WCT were statistically reliable. Comparing predictive accuracy of each model found that adding the WCT to the ACS increased predictive accuracy. Diagnostic efficiency for the full ACS model was considered “excellent” according to interpretive guidelines.

Comparisons of five performance validity indices in bona fide and simulated traumatic brain injury

A number of performance validity tests (PVTs) are used to assess memory complaints associated with traumatic brain injury (TBI); however, few studies examine the concordance and predictive accuracy of multiple PVTs, specifically in the context of combined models in known-group designs. The present study compared five widely used PVTs: the Test of Memory Malingering (TOMM), Medical Symptom Validity Test (MSVT), Reliable Digit Span (RDS), Word Choice Test (WCT), and California Verbal Learning Test – Forced Choice (CVLT-FC). Participants were 51 adults with bona fide moderate to severe TBI and 58 demographically comparable healthy adults coached to simulate memory impairment. Classification accuracy of individual PVTs was evaluated using logistic regression and receiver operating characteristic (ROC) curves, examining both the dichotomous cutting scores as recommended by the test publishers and continuous scores for the measures. Results demonstrated nearly equivalent discrimination ability of the TOMM, MSVT, and CVLT-FC as individual predictors, all of which markedly outperformed the WCT and RDS. Models of combined PVTs were examined using Bayesian information criterion statistics, with results demonstrating that diagnostic accuracy showed only small to modest growth when the number of tests was increased beyond two. Considering the clinical and pragmatic issues in deriving a parsimonious assessment battery, these findings suggest that using the TOMM and CVLT in conjunction or the MSVT and CVLT in conjunction maximized predictive accuracy as compared to a single index or an assortment of these widely used measures.

Gender Differences in Lateralized Semantic Priming

Previous literature suggests that women evidence more bilateral cerebral organization, particularly in language processing, whereas men show greater left hemisphere dominance for language. This study examined the magnitude of these gender differences in a lateralized lexical decision task and the implications of such differences to semantic processing and cerebral organization. As predicted, women, as compared to men, recruited greater bilateral hemispheric resources, as evidenced by greater contralateral hemispheric priming. Spatial skills predicted less priming in women, but not in men. Implications for laterality research in aging populations as well as future directions are discussed.

Strategies of successful and unsuccessful simulators coached to feign traumatic brain injury

Abstract Objective: The present study evaluated strategies used by healthy adults coached to simulate traumatic brain injury (TBI) during neuropsychological evaluation. Method: Healthy adults (n = 58) were coached to simulate TBI while completing a test battery consisting of multiple performance validity tests (PVTs), neuropsychological tests, a self-report scale of functional independence, and a debriefing survey about strategies used to feign TBI. Results: “Successful” simulators (n = 16) were classified as participants who failed 0 or 1 PVT and also scored as impaired on one or more neuropsychological index. “Unsuccessful” simulators (n = 42) failed ≥2 PVTs or passed PVTs but did not score impaired on any neuropsychological index. Compared to unsuccessful simulators, successful simulators had significantly more years of education, higher estimated IQ, and were more likely to use information provided about TBI to employ a systematic pattern of performance that targeted specific tests rather than performing poorly across the entire test battery. Conclusion: Results contribute to a limited body of research investigating strategies utilized by individuals instructed to feign neurocognitive impairment. Findings signal the importance of developing additional embedded PVTs within standard cognitive tests to assess performance validity throughout a neuropsychological assessment. Future research should consider specifically targeting embedded measures in visual tests sensitive to slowed responding (e.g. response time).

Diagnostic efficiency of an ability-focused battery

An ability-focused battery (AFB) is a selected group of well-validated neuropsychological measures that assess the conventional range of cognitive domains. This study examined the diagnostic efficiency of an AFB for use in clinical decision making with a mixed sample composed of individuals with neurological brain dysfunction and individuals referred for cognitive assessment without evidence of neurological disorders. Using logistic regression analyses and ROC curve analysis, a five-domain model composed of attention, processing speed, visual-spatial reasoning, language/verbal reasoning, and memory domain scores was fitted that had an AUC of.89 (95% CI =.84–.95). A more parsimonious two-domain model using processing speed and memory was also fitted that had an AUC of.90 (95% confidence interval =.84–.95). A model composed of a global ability score calculated from the mean of the individual domain scores was also fitted with an AUC of.88 (95% CI =.82–.94).

Parsimonious prediction of Wechsler Memory Scale, Fourth Edition scores: Immediate and delayed memory indexes

Research on previous versions of the Wechsler Memory Scale (WMS) found that index scores could be predicted using a parsimonious selection of subtests (e.g., Axelrod & Woodard, 2000). The release of the Fourth Edition (WMS–IV) requires a reassessment of these predictive formulas as well as the use of indices from the California Verbal Learning Test–II (CVLT–II). Complete WMS–IV and CVLT–II data were obtained from 295 individuals. Six regression models were fit using WMS–IV subtest scaled scores—Logical Memory (LM), Visual Reproduction (VR), and Verbal Paired Associates (VPA)—and CVLT–II substituted scores to predict Immediate Memory Index (IMI) and Delayed Memory Index (DMI) scores. All three predictions of IMI significantly correlated with the complete IMI (r = .92 to .97). Likewise, predicted DMI scores significantly correlated with complete DMI (r = .92 to .97). Statistical preference was indicated for the models using LM, VR, and VPA, in which 97% and 96% of the cases fell within two standard errors of measurement (SEMs) of full index scores, respectively. The present findings demonstrate that the IMI and DMI can be reliably estimated using two or three subtests from the WMS–IV, with preference for using three. In addition, evidence suggests little to no improvement in predictive accuracy with the inclusion of CVLT–II indices.

Substitution of California Verbal Learning Test, second edition for Verbal Paired Associates on the Wechsler Memory Scale, fourth edition.

Two common measures used to evaluate verbal learning and memory are the Verbal Paired Associates (VPA) subtest from the Wechsler Memory Scales (WMS) and the second edition of the California Verbal Learning Test (CVLT-II). For the fourth edition of the WMS, scores from the CVLT-II can be substituted for VPA; the present study sought to examine the validity of the substitution. For each substitution, paired-samples t tests were conducted between original VPA scaled scores and scaled scores obtained from the CVLT-II substitution to evaluate comparability. Similar comparisons were made at the index score level. At the index score level, substitution resulted in significantly lower scores for the AMI (p = .03; r = .13) but not for the IMI (p = .29) or DMI (p = .09). For the subtest scores, substituted scaled scores for VPA were not significantly different from original scores for the immediate recall condition (p = .20) but were significantly lower at delayed recall (p = .01). These findings offer partial support for the substitution. For both the immediate and delayed conditions, the substitution produced generally lower subtest scores compared to original VPA subtest scores.

Parsimonious Estimation of the Wechsler Memory Scale, Fourth Edition Demographically Adjusted Index Scores: Immediate and Delayed Memory

The recent release of the Wechsler Memory Scale Fourth Edition contains many improvements from a theoretical and administration perspective, including demographic corrections using the Advanced Clinical Solutions. Although the administration time has been reduced from previous versions, a shortened version may be desirable in certain situations given practical time limitations in clinical practice. The current study evaluated two- and three-subtest estimations of demographically corrected Immediate and Delayed Memory index scores using both simple arithmetic prorating and regression models. All estimated values were significantly associated with observed index scores. Use of Lins Concordance Correlation Coefficient as a measure of agreement showed a high degree of precision and virtually zero bias in the models, although the regression models showed a stronger association than prorated models. Regression-based models proved to be more accurate than prorated estimates with less dispersion around observed values, particularly when using three subtest regression models. Overall, the present research shows strong support for estimating demographically corrected index scores on the WMS-IV in clinical practice with an adequate performance using arithmetically prorated models and a stronger performance using regression models to predict index scores.