Depression is the psychiatric co-morbidity most commonly associated with Parkinson's disease (PD). However, depression is often under-diagnosed and under-recognized and the affected patients seldom receive treatment for this psychiatric disorder. The objective of the present study was to determine the prevalence of major depression among Brazilian patients with a diagnosis of PD.

The study was conducted at the movement disorders outpatient clinic of the University Hospital, Faculty of Medicine of Ribeirão Preto. A total of 111 consecutive patients with a diagnosis of PD were selected and independently interviewed using the SCID-IV-CV (DSM-IV). Patients with dementia associated with PD were excluded.

Patient age ranged from 24 to 85 years (mean: 61.2 + 12.7 years). Fifty-eight of the 102 patients (52.3%) were females and 53 (47.7%) were males. The current prevalence of depression was 26.1% (29) and the lifetime was 57.7% (64). Regarding gender, the current prevalence of depression was 15.1% (9) for males and 36.2% (21) for females, with the difference being statistically significant (p<0.01). The lifetime prevalence of depression was 33.4% (23) for males and 70.7% (41) for females (p<0.01).

The high prevalence of major depression among patients with PD and the predominance of women detected in this study are comparable to the rates observed in studies conducted in other countries. Strategies for an early diagnosis and adequate treatment appear to be necessary and opportune in order to improve the quality of life of the patients and to prevent possible complications such as suicide.