Access to Semantic Memory in Parkinson's Disease and Multiple Sclerosis

Abstract

The capacity to access semantic memory and the efficiency of the memory search were studied in patients with Parkinson's disease (PD) or multiple sclerosis (MS) using a modified version of the "Supermarket Test." PD and MS patients who performed normally on the Boston Naming Test generated as many specific exemplars and category labels as did controls, and these patients also searched their semantic memories as efficiently as controls. In contrast, PD and MS patients with impaired confrontational naming generated fewer specific exemplars, but a normal number of generic category labels. These naming-impaired patients searched their semantic memories less efficiently than controls. For both MS and PD patients, the efficiency of semantic memory search was significantly correlated with measures that reflect access to semantic memory (eg, performance on letter or category fluency tasks), but was not significantly related to measures of problem-solving ability derived from the Wisconsin Card Sorting Test. Inefficient search of semantic memory in MS and PD appears to arise from an inability to retrieve knowledge from semantic memory quickly or from the loss of information from semantic memory stores, rather than from impairment in the ability to formulate and deploy appropriate strategies for task solution. ( J Geriatr Psychiatry Neurol 1989; 2:153-162).