Word memory test performance in amnesic patients with hippocampal damage.

Abstract

Many symptom validity tests (SVTs) assess performance validity via declarative memory paradigms. One widely used SVT, the Word Memory Test (WMT), uses a variety of memory tests to assess performance. It is well known that declarative memory requires the hippocampus and related medial temporal lobe structures. In the present study, WMT performance was examined in nonlitigating amnesic subjects (n = 3) with well-documented focal bilateral hippocampal atrophy who were nondemented and otherwise cognitively unimpaired compared with matched controls. The amnesic subjects had no external incentives. Amnesic subjects performed significantly below the level of matched comparison subjects but above established cutoff scores on the immediate recognition and delay recognition subtests and consistency component. In contrast, the amnesic subjects were impaired relative to our comparison subjects on the multiple-choice, paired associate, free-recall, and long delay free-recall subtests and had extremely low performance on these measures. Thus, there was a differential effect of hippocampal damage on WMT performance where the recognition subtests were performed within the normal range, yet the free recall was profoundly impaired in amnesic subjects. Such an approach where SVT performance is assessed in populations with well-known cognitive impairments adds breadth to SVT clinical interpretations.