Prevalence of depression in Parkinson's disease: effects of disease stage, motor subtype and gender.

Depression is one of the most common non-motor symptoms of Parkinson's disease (PD) with a large negative impact on the quality of life. Factors such as disease stage, subtype of PD and gender might play an important role in the prevalence of depression, but a large study investigating all these factors in a within-subject design is lacking. Therefore we studied a homogeneous group of 256 Dutch PD patients (60% men, mean age=65.12 (±9.6) years). In total, 36.3% of the subjects had a BDI-score indicative for a minor depression, while 12.9% had a major depression. Notably, only 8.6% of the minor depressed patients and 30.3% of the major depressed patients were taking antidepressants. A higher prevalence of depression was observed in the later stages of the disease. However, this finding was absent in a smaller subsample after correction for cognitive impairment. Our data did not show a difference in the prevalence of depression between the motor subtypes and showed a trend towards higher prevalence of depression in the tremor dominant group. There was no significant difference in the prevalence of depression between men and women. We will discuss the relevance of these results in relation to the findings of other studies.