Weight loss in patients treated long-term with levodopa. Metabolic aspects

Seven aged Parkinsonian patients treated with levodopa (average dose 3-4 g daily for 1-3 years), showed a considerable weight loss. They were compared to two control groups of elderly and young volunteers after levodopa stimulation and after oral glucose tolerance tests. It was found that after levodopa administration the plasma free fatty acids, glucose, growth hormone and cortisol were significantly higher in the Parkinsonian group than in the young control group and only slightly higher than in the aged control group. It was also found that the serum insulin was significantly higher in Parkinsonian patients than in the aged control group. We think that the metabolic disturbances found in Parkinsonian patients are not solely due to levodopa administration but may be due to ageing processes. We suggest that weight loss in the older Parkinsonian patients treated over long periods with high doses of levodopa, is due to the enhancement of the lipolytic activity of the ageing fat cells caused by high levels of circulating insulin.