DRUG-INDUCED PARKINSONISM AS A RISK FACTOR FOR PARKINSONS-DISEASE - AHISTORICAL COHORT STUDY IN OLMSTED COUNTY, MINNESOTA

Objective: To investigate whether subjects who experienced a reversibl e episode of drug-induced parkinsonism have an increased risk of subse quent Parkinson's disease, Design: We undertook a historical cohort st udy based on the medical records-linkage system of the Rochester Epide miology Project in Olmsted County, Minnesota, Material and Methods: Al l subjects' in whom drug-induced parkinsonism developed between 1955 a nd 1990 and was indexed in the medical records-linkage system were ide ntified, in the 24 eligible subjects, follow-up for the subsequent dev elopment of Parkinson's disease consisted of a total of 192.7 person-y ears. The observed number of cases of Parkinson's disease was compared with the expected number of cases in an age- and sex-matched cohort f rom the general population. Results: In 2 of 24 subjects with drug-ind uced parkinsonism, Parkinson's disease later developed, A comparison w ith the expected number of cases in the general population (0.08) yiel ded a relative risk of 23.3 (95% confidence interval, 2.9 to 87.5; P = 0.006), Conclusion: Our findings suggest that drug-induced parkinsoni sm is associated with an increased risk of Parkinson's disease. Clarif ication of the mechanisms of this association may have preventive impl ications.