Effects of levodopa therapy in Parkinson's disease. II. Measurement of behavioural changes.

Forty-seven patients with Parkinson's disease were evaluated prior to and during levodopa treatment (at five weeks and at six months), to obtain quantitative measures of the effects of the disease and of levodopa on a variety of cognitive and psychomotor functions, by means of psychological tests and special apparatus. Analysis of the findings in relation to a comparable control group shows that before treatment patients had impaired performance of all motor tasks, but no differences in cognitive functioning were found. Most motor functions had improved after five weeks on levodopa and this improvement was maintained at the six-month follow-up, but cognitive functions remained largely unchanged. The relationship between patients' age, disability, duration of illness and drug tolerance is also discussed in relation to the functions measured.