Levodopa treatment is unquestionably the reason parkinsonian patients now live a normal1 or nearnormal2 life span. When in the course of the disease levodopa therapy should begin remains controversial for several reasons: the initial favorable response to the drug is followed by a gradual decline; the impression that levodopa has a finite period of optimal usefulness3; and the assumption that severe dyskinesia and a true "on-off" effect are related to duration of treatment. These suggestions have led some to believe that levodopa should be held in reserve until the patient is at least moderately afflicted, so that it is not "wasted" on early stages of the disease.
Our data lead us to conclude that this reasoning is fallacious. When the condition of a patient with a progressive disease who is receiving long-term drug treatment is seen to worsen over time, two possibilities arise. The first is that
Markham CH, Diamond SG. Modification of Parkinson's Disease by Long-term Levodopa Treatment. Arch Neurol. 1986;43(4):405–407. doi:10.1001/archneur.1986.00520040083026