FRONTO-STRIATAL COGNITIVE DEFICITS AT DIFFERENT STAGES OF PARKINSON'S DISEASE

TLDR

The study compares these findings with data from young neurosurgical patients who had localized frontal lobe excisions to explore the specific cognitive deficits that emerge at different stages of Parkinson’s disease. The authors compared medicated and unmedicated idiopathic Parkinson’s patients with matched healthy controls using a computerized battery sensitive to frontal‑lobe dysfunction, comprising tests of planning, spatial working memory, and attentional set‑shifting. Medicated Parkinson’s patients exhibited deficits in planning time, accuracy (in severe cases), and spatial working memory, whereas early unmedicated patients performed normally on these tasks; however, all PD groups showed impaired attentional set‑shifting while pattern‑recognition abilities remained intact.

Abstract

Groups of patients with idiopathic Parkinson's disease, either medicated or unmedicated, were compared with matched groups of normal controls on a computerized battery previously shown to be sensitive to frontal lobe dysfunction, including tests of planning, spatial working memory and attentional set-shifting. In a series of problems based on the ‘Tower of London’ test, medicated patients with Parkinson's disease were shown to be impaired in the amount of time spent thinking about (planning) the solution to each problem. Additionally, an impairment in terms of the accuracy of the solution produced on this test was only evident in those patients with more severe clinical symptoms and was accompanied by deficits in an associated test of spatial short-term memory. Medicated patients with both mild and severe clinical symptoms were also impaired on a related test of spatial working memory. In contrast, a group of patients who were unmedicated and ‘early in the course’ of the disease were unimpaired in all three of these tests. However, all three Parkinson's disease groups were impaired in the test of attentional set-shifting ability, although unimpaired in a test of pattern recognition which is insensitive to frontal lobe damage. These data are compared with those previously published from a group of young neurosurgical patients with localized excisions of the frontal lobes and are discussed in terms of the specific nature of the cognitive deficit at different stages of Parkinson's diseas.