Depression and major depressive disorder in patients with Parkinson's disease.

The prevalence of depression in Parkinson's disease (PD) varies greatly. In this study, we investigated major depressive disorder (MDD) and depressive symptoms without MDD in patients with PD. The psychopathological characteristics of depressive symptoms were assessed by a psychiatric interview. A total of 105 Japanese patients with PD without dementia were included. The Japanese version of the Beck Depression Inventory-II (BDI-II) with a cutoff score of 13/14 was used to screen for depression. Using a structured interview, a comprehensive psychiatric evaluation of patients with BDI-II scores >13 (high BDI patients) was completed using the criteria of the Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV-TR. Forty patients (38%) had a BDI-II >13, but 29 did not show any depressed mood. Five cases met the criteria for MDD (three current, two past) and one patient was diagnosed with minor depressive disorder. A slight depressed mood that was associated with worrying about PD was seen in 6 of 34 patients without any depressive disorder and fluctuated with aggravation of PD symptoms in two of these patients. For the diagnosis of MDD, the number of positive items from the DSM-IV-TR definition of MDD is most important and useful for differentiating MDD and non-MDD. The low-prevalence rate of MDD in our patient population suggests that PD may be a psychological stressor for MDD, but does not necessarily induce MDD.