Drug-induced parkinsonism as a risk factor for Parkinson's disease: a historical cohort study in Olmsted County, Minnesota.
OBJECTIVE
To investigate whether subjects who experienced a reversible episode of drug-induced parkinsonism have an increased risk of subsequent Parkinson's disease.


METHODS
We undertook a historical cohort study based on the medical records-linkage system of the Rochester Epidemiology Project in Olmsted County, Minnesota.


METHODS
All subjects in whom drug-induced parkinsonism developed between 1955 and 1990 and was indexed in the medical records-linkage system were identified. In the 24 eligible subjects, follow-up for the subsequent development of Parkinson's disease consisted of a total of 192.7 person-years. The observed number of cases of Parkinson's disease was compared with the expected number of cases in an age- and sex-matched cohort from the general population.


RESULTS
In 2 of 24 subjects with drug-induced parkinsonism, Parkinson's disease later developed. A comparison with the expected number of cases in the general population (0.08) yielded a relative risk of 24.3 (95% confidence interval, 2.9 to 87.5; P = 0.006).


CONCLUSIONS
Our findings suggest that drug-induced parkinsonism is associated with an increased risk of Parkinson's disease. Clarification of the mechanisms of this association may have preventive implications.
Chabolla
D R
DR
Department of Neurology, Mayo Clinic Jacksonville, Florida 32224, USA.
Maraganore
D M
DM
Ahlskog
J E
JE
O'Brien
P C
PC
Rocca
W A
WA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000209:etiology*; D010302:Parkinson Disease, Secondary / Q000139:chemically induced* / Q000150:complications*; D012306:Risk; D012307:Risk Factors