Background: Antidepressant use is more common in people with Parkinson's disease (PD), but it is unknown when this difference emerges.
Methods: We studied the incidence of antidepressant use in six-month periods from 10 years before to 15 years after PD diagnosis in the nationwide register-based Finnish Study on Parkinson's disease (FINPARK). This study included 20,456 community dwellers with clinically verified PD diagnosed during 1996-2015 and 140,291 matched comparison persons.
Results: Altogether 44.3% of people with PD initiated antidepressants, compared to 25.0% of people without PD. The difference was largest 6 months before PD diagnosis (incidence rate ratio 5.28, 95% CI 4.80-5.80; 9.02 and 1.68 initiations/100 person-years in people with and without PD, respectively). The difference emerged already 7 years before the diagnosis and remained above the comparison group for most of the study period.
Conclusions: Persons with PD may have symptoms that require antidepressant treatment years before and after diagnosis. The symptoms needing antidepressant treatment may be clinical signs of possible PD and they should be considered as a need to assess clinical status in person diagnosed with PD.
Keywords: Antidepressant; Cohort studies; Epidemiology; Incidence; Parkinson’s disease.