Performance validity tests in people with epilepsy: A review of the literature

Abstract

Objective

Professional bodies recommend the use of performance validity tests (PVTs) to aid the interpretation of scores obtained in neuropsychological assessments, but base rates of failure differ according to neurological diagnosis and the associated impairments. This review summarises the PVT literature in people with epilepsy with the aim of establishing base rates of PVT failure and the factors associated with PVT performance in this population.

Methods

Ovid and PubMed databases were searched for studies reporting PVT test performance in people with epilepsy.

Results

The search strategy identified 29 studies reporting the performance of people with epilepsy on 23 PVTs. The most commonly reported PVTs were memory-based tasks including the Test of Memory Malingering (n=15) and the Word Memory Test (n=9). Highly variable failure rates were reported on these tasks using cut-offs established in other neurological groups. Factors associated with apparent failure on PVTs in people with epilepsy included older age, lower IQ, attention deficits, impaired verbal and working memory and epilepsy-related factors including a left sided seizure focus, the presence of interictal EEG abnormalities and recent seizure activity.

Conclusions

Epilepsy related factors are associated with apparent failures on some PVTs. Caution should be employed when interpreting scores on memory based PVTs in this population.