Date of Award
Doctor of Philosophy (PhD)
Patients with epilepsy are considered a motivated population without clear incentive to perform suboptimally on neuropsychological testing. However, in the limited research exploring performance validity testing (PVT) in patients with epilepsy, the base rate of suboptimal performance has ranged from 4 (Hill, Ryan, Kennedy, & Malamut, 2003) to 28% (Loring, Lee, & Meador, 2005). These findings are concerning, as suboptimal PVT scores have been found to be associated with significantly lower neuropsychological performance across most cognitive domains (e.g., Green, Rohling, Lees-Haley, & Allen, 2001). One possible explanation for the variance in base rate of suboptimal performance is the significant cognitive impairment commonly associated with epilepsy (Bortz, 2003). The present study investigated this unexplored theory by utilizing the Word Memory Test (WMT). The WMT is a PVT that indicates whether scores below failure cutoff likely reflect suboptimal performance or significant cognitive impairment, a determination made by General Memory Impairment Profile (GMIP) analysis. Using WMT normative cutoffs, patients in the current study were categorized into optimal, suboptimal, and GMIP performance groups. Subsequently, differences among groups on a variety of neuropsychological measures were explored. The validity of the GMIP was also examined to provide support for its use with this population. Findings indicated that 43% of the sample fell into the WMT optimal group, 36% into the suboptimal group, and 21% into the GMIP group. Although WMT performance accounted for 29% of the variance in overall neuropsychological performance, PV did not impact all cognitive domains equally. WMT performance groups scored significantly differently across most neuropsychological measures; patients in the suboptimal and GMIP groups typically obtained significantly lower scores than patients in the optimal group. Results also largely supported the validity of the GMIP in its ability to identify WMT scores below failure cutoff due to borderline memory impairment. Overall, current findings encourage the use and further investigation of the WMT and GMIP analysis in patients with epilepsy.