The TOMM1 discrepancy index (TDI): A new performance validity test (PVT) that differentiates between invalid cognitive testing and those diagnosed with dementia

The classification accuracy of Warrington's recognition memory test (words) as a performance validity Test in a neurorehabilitation setting

This study was designed to evaluate the classification accuracy of the Warrington's Recognition Memory Test (RMT) in 167 patients (97 or 58.1% men; MAge = 40.4; MEducation= 13.8) medically referred for neuropsychological evaluation against five psychometrically defined criterion groups. At the optimal cutoff (≤42), the RMT produced an acceptable combination of sensitivity (.36-.60) and specificity (.85-.95), correctly classifying 68.4-83.3% of the sample. Making the cutoff more conservative (≤41) improved specificity (.88-.95) at the expense of sensitivity (.30-.60). Lowering the cutoff to ≤40 achieved uniformly high specificity (.91-.95) but diminished sensitivity (.27-.48). RMT scores were unrelated to lateral dominance, education, or gender. The RMT was sensitive to a three-way classification of performance validity (Pass/Borderline/Fail), further demonstrating its discriminant power. Despite a notable decline in research studies focused on its classification accuracy within the last decade, the RMT remains an effective free-standing PVT that is robust to demographic variables. Relatively low sensitivity is its main liability. Further research is needed on its cross-cultural validity (sensitivity to limited English proficiency).

The impact of race and other demographic factors on the false positive rates of five embedded Performance Validity Tests (PVTs) in a Veteran sample

INTRODUCTION

It is common to use normative adjustments based on race to maintain accuracy when interpreting cognitive test results during neuropsychological assessment. However, embedded performance validity tests (PVTs) do not adjust for these racial differences and may result in elevated rates of false positives in African American/Black (AA) samples compared to European American/White (EA) samples.

METHODS

Veterans without Major Neurocognitive Disorder completed an outpatient neuropsychological assessment and were deemed to be performing in a valid manner (e.g., passing both the Test of Memory Malingering Trial 1 (TOMM1) and the Medical Symptom Validity Test (MSVT), (n = 531, EA = 473, AA = 58). Five embedded PVTs were administered to all patients: WAIS-III/IV Processing Speed Index (PSI), Brief Visuospatial Memory Test-Revised: Discrimination Index (BVMT-R), TMT-A (secs), California Verbal Learning Test-II (CVLT-II) Forced Choice, and WAIS-III/IV Digit Span Scaled Score. Individual PVT false positive rates, as well as the rate of failing two or more embedded PVTs, were calculated.

RESULTS

Failure rates of two embedded PVTs (PSI, TMT-A), and the total number of PVTs failed, were higher in the AA sample. The PSI and TMT-A remained significantly impacted by race after accounting for age, education, sex, and presence of Mild Neurocognitive Disorder. There were PVT failure rates greater than 10% (and considered false positives) in both groups (AA: PSI, TMT-A, and BVMT-R, 12-24%; EA: BVMT-R, 17%). Failing 2 or more PVTs (AA = 9%, EA = 4%) was impacted by education and Mild Neurocognitive Disorder but not by race.

CONCLUSIONS

Individual (timed) PVTs showed higher false positive rates in the AA sample even after accounting for demographic factors and diagnosis of Mild Neurocognitive Disorder. Requiring failure on 2 or more embedded PVTs reduced false positive rates to acceptable levels across both groups (10% or less) and was not significantly influenced by race.

Performance validity of the Dot Counting Test in a dementia clinic setting

OBJECTIVE

This study examined the utility of a performance validity test (PVT), the Dot Counting Test (DCT), in individuals undergoing neuropsychological evaluations for dementia. We investigated specificity rates of the DCT Effort Index score (E-Score) and various individual DCT scores (based on completion time/errors) to further establish appropriate cutoff scores.

METHOD

This cross-sectional study included 56 non-litigating, validly performing older adults with no/minimal, mild, or major cognitive impairment. Cutoffs associated with ≥90% specificity were established for 7 DCT scoring methods across impairment severity subgroups.

RESULTS

Performance on 5 of 7 DCT scoring methods significantly differed based on impairment severity. Overall, more severely impaired participants had significantly higher E-Scores and longer completion times but demonstrated comparable errors to their less impaired counterparts. Contrary to the previously established E-Score cutoff of ≥17, a cutoff of ≥22 was required to maintain adequate specificity in our total sample, with significantly higher adjustments required in the Mild and Major Neurocognitive Disorder subgroups (≥27 and ≥40, respectively). A cutoff of >3 errors achieved adequate specificity in our sample, suggesting that error scores may produce lower false positive rates than E-Scores and completion time scores, both of which overemphasize speed and could inadvertently penalize more severely impaired individuals.

CONCLUSIONS

In a dementia clinic setting, error scores on the DCT may have greater utility in detecting non-credible performance than E-Scores and completion time scores, particularly among more severely impaired individuals. Future research should establish and cross-validate the sensitivity and specificity of the DCT for assessing performance validity.

Multivariate Models of Performance Validity: The Erdodi Index Captures the Dual Nature of Non-Credible Responding (Continuous and Categorical)

This study was designed to examine the classification accuracy of the Erdodi Index (EI-5), a novel method for aggregating validity indicators that takes into account both the number and extent of performance validity test (PVT) failures. Archival data were collected from a mixed clinical/forensic sample of 452 adults referred for neuropsychological assessment. The classification accuracy of the EI-5 was evaluated against established free-standing PVTs. The EI-5 achieved a good combination of sensitivity (.65) and specificity (.97), correctly classifying 92% of the sample. Its classification accuracy was comparable with that of another free-standing PVT. An indeterminate range between Pass and Fail emerged as a legitimate third outcome of performance validity assessment, indicating that the underlying construct is an inherently continuous variable. Results support the use of the EI model as a practical and psychometrically sound method of aggregating multiple embedded PVTs into a single-number summary of performance validity. Combining free-standing PVTs with the EI-5 resulted in a better separation between credible and non-credible profiles, demonstrating incremental validity. Findings are consistent with recent endorsements of a three-way outcome for PVTs (Pass, Borderline, and Fail).

Failing Performance Validity Cutoffs on the Boston Naming Test (BNT) Is Specific, but Insensitive to Non-Credible Responding

This study was designed to examine alternative validity cutoffs on the Boston Naming Test (BNT).Archival data were collected from 206 adults assessed in a medicolegal setting following a motor vehicle collision. Classification accuracy was evaluated against three criterion PVTs.The first cutoff to achieve minimum specificity (.87-.88) was T ≤ 35, at .33-.45 sensitivity. T ≤ 33 improved specificity (.92-.93) at .24-.34 sensitivity. BNT validity cutoffs correctly classified 67-85% of the sample. Failing the BNT was unrelated to self-reported emotional distress. Although constrained by its low sensitivity, the BNT remains a useful embedded PVT.

Are there differences in performance validity test scores between African American and White American neuropsychology clinic patients?

OBJECTIVE

The purpose of the present study was to compare performance on a wide range of PVTs in a neuropsychology clinic sample of African Americans and White Americans to determine if there are differences in mean scores or cut-off failure rates between the two groups, and to identify factors that may account for false positive PVT results in African American patients.

METHOD

African American and White American non-compensation-seeking neuropsychology clinic patients were compared on a wide range of standalone and embedded PVTs: Dot Counting Test, b Test, Warrington Recognition Memory Test, Rey 15-item plus recognition, Rey Word Recognition Test, Digit Span (ACSS, RDS, 3-digit time, 4-digit time), WAIS-III Picture Completion (Most discrepant index), WAIS-III Digit Symbol/Coding (recognition equation), Rey Auditory Verbal Learning Test, Rey Complex figure, WMS-III Logical Memory, Comalli Stroop Test, Trails A, and Wisconsin Card Sorting Test.

RESULTS

When groups were equated for age and education, African Americans obtained mean performances significantly worse than White Americans on only four of 25 PVT scores across the 14 different measures (Stroop Word Reading and Color Naming, Trails A, Digit Span 3-digit time); however, FSIQ was also significantly higher in White American patients. When subjects with borderline IQ (FSIQ = 70 to 79) were excluded (resulting in 74 White Americans and 25 African Americans), groups no longer differed in IQ and only continued to differ on a single PVT cutoff (Trails A). Further, specificity rates in African Americans were comparable to those of White Americans with the exception of the b Test, the Dot Counting Test, and Stroop B.

CONCLUSIONS

PVT performance generally does not differ as a function of Black versus White race once the impact of intellectual level is controlled, and most PVT cutoffs appear appropriate for use in African Americans of low average IQ or higher.