Objective: This study investigated the base rates of performance validity test (PVT) failure on neuropsychological testing in a sample of patients seeking surgical intervention (DBS/MRgFUS) for management of tremor or dystonia.

Background: PVTs are used in neuropsychological evaluations to help determine the validity of cognitive test performance. PVT failure is often interpreted to be due to feigning or malingering, though failure can occur due to suboptimal engagement and/or true cognitive deficits. Patients who undergo neuropsychological testing as part of their presurgical workup are presumably highly motivated to do well on cognitive testing, as cognitive impairment at baseline can be a contraindication to surgery. Understanding base rates of PVT failure for patients being considered for these interventions is important to determine which PVTs are most appropriate as using PVTs least likely to yield false positive errors (PVT failure in the absence of feigning/malingering) is vital to ensure informed decision-making and positive postsurgical outcomes.

Method: Data were collected from 56 consecutive movement disorder patients (66% male, Mage=67.3, Meducation=15 years, 89% White) undergoing outpatient neuropsychological evaluation for DBS or MRgFUS candidacy. All patients underwent comprehensive testing including freestanding (Test of Memory Malingering [TOMM, Trial 1]; Coin-In-The-Hand [CIH]) and embedded (Wechsler Adult Intelligence Scale—Fourth Edition, Reliable Digit Span [WAIS-IV RDS], Hopkins Verbal Learning Test—Revised, Recognition Discrimination [HVLT-RD], Stroop Word Reading T Score [Stroop]) PVTs.

Results: Overall, 21.4% of patients failed at least one PVT. Two patients (3.6%) failed ≥2 PVTs, and an additional 10 patients (17.9%) failed exactly one PVT. On embedded PVTs, failure rates were as follows: WAIS-IV RDS: 6%; HVLT-RD: 12%; Stroop: 4%. On freestanding PVTs, no patients failed CIH and one of 29 patients (3.4%) failed TOMM T1.

Conclusion: Patients presenting for presurgical neuropsychological evaluations demonstrated a higher PVT failure rate than what is expected for this population. Seven of 12 patients (58.3%) who failed at least one PVT were determined to have a diagnosis of dementia, suggesting that PVT failures for these patients may reflect true cognitive deficits. Given the high invalidity rate on HVLT-RD, further research is necessary to cross-validate established cut-scores in this population.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/performance-validity-test-failure-base-rates-among-presurgical-movement-disorder-patients/