Prevalence of depression in Parkinson's disease

Background: The recognition of depression prevalence in Parkinson's disease (PD) is necessary for the development of treatment techniques as well as the improvement in the patient's quality of life. Objective: To identify in the literature studies related to the prevalence of depression in PD. Methods: The search for articles was based on PubMed, LILACS and SciELO matching the key-words prevalence, depression and Parkinson. Inclusion criteria of articles were: papers in English, Portuguese and Spanish; without time limitation. Articles related to the treatment of PD and to the validation of scales were excluded. Results: A total of 20 studies were selected, including six case-control studies, 3 longitudinal (2 cohort) studies, and 43 non-sectional studies. Prevalence rates ranged from 1.8% to 68.1%. Concerning the evaluation of techniques employed, eight studies used clinical interviews, nine used just self-report instruments, one utilized clinical interviews and self-report instruments and four consulted data bases. Discussion: The prevalence of depression varied according to the methodology, however, in general, rates proved to be considerably elevated. The analysis reveals the necessity of more precise and consensual definitions regarding depression in PD so that more accurate prevalence rates can be obtained.