Risk of Parkinson disease after depression: a nationwide population-based study

To evaluate the risk of Parkinson disease (PD) among patients with depression by using the Taiwan National Health Insurance Research Database (NHIRD).

We conducted a retrospective study of a matched cohort of 23,180 participants (4,634 patients with depression and 18,544 control patients) who were selected from the NHIRD. Patients were observed for a maximum of 10 years to determine the rates of new-onset PD, and Cox regression was used to identify the predictors of PD. We also examined the risk of PD after excluding patients who were diagnosed with PD within 2 or 5 years after their depression diagnosis. A logistic regression model was used to identify risk factors associated with PD onset in patients with depression.

During the 10-year follow-up period, 66 patients with depression (1.42%) and 97 control patients (0.52%) were diagnosed with PD. After adjusting for age and sex, patients with depression were 3.24 times more likely to develop PD (95% confidence interval 2.36-4.44, p < 0.001) compared with the control patients. After excluding patients who were diagnosed with PD within 2 or 5 years after their depression diagnosis, patients with depression had a higher hazard ratio for developing PD than the control patients. The odds ratios for age (1.09) and difficult-to-treat depression (2.18) showed that each is an independent risk factor for PD in patients with depression.

The likelihood of developing PD is greater among patients with depression than patients without depression. Depression may be an independent risk factor for PD.