DOPAMINE-DEPENDENT FRONTOSTRIATAL PLANNING DEFICITS IN EARLY PARKINSONS-DISEASE

Three groups of medicated and nonmedicated patients at different stage s of Parkinsons disease and a group of neurosurgical patients with loc alized frontal lobe excisions were assessed on 2 novel tests of planni ng and spatial working memory. Results demonstrate that, like other te sts of frontal lobe dysfunction, planning and spatial working memory a re vulnerable in nonmedicated patients with mild Parkinson's disease a nd suggest that certain aspects of the planning impairment in these pa tients may be ameliorated by dopaminergic therapy. Specifically, with medication there was an improvement in accuracy of planning, but not i n latency, in a series of problem!, based on the Tower of London test of planning. The results in terms of the frontostriatal, dopamine-depe ndent nature of some of the cognitive deficits found in early Parkinso n's disease versus the apparent dopamine-independent nature of deficit s in other cognitive processes are discussed.