The Graeme Robertson memorial lecture, 1983. The long-term prognosis of Parkinson's disease.

Review after more than ten years' treatment shows that Parkinson's disease continues to progress in about 50% of patients. This progression involves mainly gait and equilibrium, but akinesia and speech deteriorate also, though at a slower rate. Organic dementia appears in about 40% of parkinsonian patients, mainly after ten years of treatment. Only 17% of patients enjoy a benign course, mild from the outset and without progression after ten years' treatment.