Reduced working memory span in Parkinson's disease: Evidence for the role of a frontostriatal system in working and strategic memory

Working and strategic memory were examined in unmedicated patients with Parkinson's disease who had neither depression nor dementia. The patients, relative to control participants, had reduced working memory spans for verbal and arithmetic material. They also had impairment on strategic memory tests of free recall, temporal ordering, and self-ordered pointing, but no impairment on tests ol recognition memory and semantic memory. Impairments in working memory capacity correlated with impairments in strategic memory and with a measure of perceptual-motor speed, but not with motor speed. It is hypothesized that a frontostriatal memory system, in which dopamine plays a critical role, mediates perceptual-motor processing speed that contributes to working memory capacity, which, in turn, contributes to strategic memory performance.