Treatment with antidepressants and lithium is associated with increased risk of treatment with antiparkinson drugs: a pharmacoepidemiological study

Objective: To estimate the risk for persons treated with antidepressants or lithium of subsequent treatment with antiparkinson drugs (APD). Methods: The Danish national prescription database supplied data on all persons who received antidepressants, lithium, or antidiabetics (first control group). A second control group was included comprising persons from the general population. Outcome was purchase of APD and the study period was 1995 to 1999. Results: In total, 1293789 persons were included. The rate ratio of treatment with APD after treatment with antidepressants was 2.27 ( 95% CI 2.14 to 2.42) for men and 1.50 (95% CI 1.43 to 1.58) for women. Figures for lithium were almost identical. Conclusion: Persons treated with antidepressants or lithium are at increased risk of subsequently treatment with APD, showing an association between anxiety/affective disorder and Parkinson's disease.