Standalone Performance Validity Tests May Be Differentially Related to Measures of Working Memory, Processing Speed, and Verbal Memory in Patients With Multiple Sclerosis.

Abstract

Cognitive functioning may account for minimal levels (i.e., 5%-14%) of variance of performance validity test (PVT) scores in clinical examinees. The present study extended this research twofold: (a) by determining the variance cognitive functioning explains within three distinct PVTs (b) in a sample of patients with multiple sclerosis (pwMS). Seventy-five pwMS (Mage = 48.50, 70.6% female, 80.9% White) completed the Victoria Symptom Validity Test (VSVT), Word Choice Test (WCT), Dot Counting Test (DCT), and three objective measures of working memory, processing speed, and verbal memory as part of clinical neuropsychological assessment. Regression analyses in credible groups (ns ranged from 54 to 63) indicated that cognitive functioning explained 24% to 38% of the variance in logarithmically transformed PVT variables. Variance from cognitive testing differed across PVTs: verbal memory significantly influenced both VSVT and WCT scores; working memory influenced VSVT and DCT scores; and processing speed influenced DCT scores. The WCT appeared least related to cognitive functioning of the included PVTs. Alternative plausible explanations, including the apparent domain/modality specificity hypothesis of PVTs versus the potential sensitivity of these PVTs to neurocognitive dysfunction in pwMS were discussed. Continued psychometric investigations into factors affecting performance validity, especially in multiple sclerosis, are warranted.