Treatment with antiparkinson and antidepressant drugs: a register-based, pharmaco-epidemiological study.

Depressive symptoms and major depression are frequent in patients with Parkinson's disease (PD). However, a systematic knowledge about the treatment with antidepressant drugs among PD patients is missing. We estimated the frequency of antidepressant drug treatment in a national sample of persons treated with antiparkinson drugs (APDs). All persons treated with APDs were identified in the national Danish Prescription database. The subsequent risk of treatment with antidepressants was estimated and compared with the risks for two large control groups. The study period was 5 years. In total, 1,029,737 persons were included. Persons who got APDs had significantly increased rate ratios (RR) of subsequent antidepressant drug treatment compared with an unexposed control group (RR: 2.10 (95% CI: 2.04-2.16)) and with persons who got anti-diabetic drugs [RR: 1.58 (95% CI: 1.51-1.65)]. In conclusion, persons treated with APDs have higher frequency of antidepressant drug treatment than have controls. With the reservation that data on drug consumption cannot be directly transferred into conclusions about specific diseases, the present study supports results from other population-based studies of an association between PD and depression. (C) 2007 Movement Disorder Society.