The TOMM1 discrepancy index (TDI): A new performance validity test (PVT) that differentiates between invalid...

Area of Science:

• Neuropsychology
• Cognitive Assessment
• Psychometrics

Background:

• Accurate performance validity tests (PVTs) are crucial for distinguishing severe cognitive decline from invalid testing.
• Existing PVTs may lack sensitivity or specificity in identifying genuine cognitive impairment versus feigned deficits.

Purpose of the Study:

• To develop and validate the TOMM1 Discrepancy Index (TDI) as a novel PVT.
• To assess the TDI's ability to identify dementia and detect suspected invalid cognitive test performance.

Main Methods:

• The TDI was developed using data from veterans with dementia (n=251) by calculating the difference between TOMM1 and MSVT Free Recall scores.
• Cutoffs were established using the dementia sample and applied to a non-dementia sample (n=1,226) to identify suspected invalid performance (n=401).
• The diagnostic accuracy of combining TOMM1 and TDI was evaluated.

Main Results:

• The TDI demonstrated high specificity (0.97) in the dementia sample when combined with TOMM1 at a cutoff of ≤28 points.
• The TDI identified suspected invalid test performance with a sensitivity of 0.75, significantly higher than the MSVT Genuine Memory Impairment Profile (GMIP) sensitivity of 0.49.
• The TDI correctly classified individuals with dementia and identified a substantial proportion with invalid performance.

Conclusions:

• The TDI, by incorporating a neurologically plausible score pattern across two PVTs, offers improved classification of dementia.
• This complex performance pattern analysis enhances the detection of individuals suspected of invalid cognitive testing.
• The TDI shows promise in reducing the ability to fabricate cognitive deficits during assessments.