Prevalence and clinical aspects of depression in Parkinson's disease: A systematic review and meta‑analysis of 129 studies.

Depression is one of the most important non-motor symptoms in Parkinson's disease (PD), but its prevalence and related clinical characteristics are unclear. To this end, we performed a systematic review and meta-analysis based on 129 studies, including 38304 participants from 28 countries. Overall, the prevalence of depression in PD was 38 %. When compared with patients without depression, those with depression had a younger age of onset, a lower education level, longer disease duration, higher UPDRS-III, higher H&Y staging scale, and lower MMSE, SE-ADL scores. We observed that depression was associated with female patients, patients carrying the GBA1 mutation, freezing of gait (FOG), apathy, anxiety and fatigue. Our results suggest that depression is an independent, frequent non-motor symptom in PD, appearing in the early stage and persisting throughout the disease duration. In addition, several clinical characteristics and motor and non-motor symptoms appeared to be associated with depression and negatively impacted on quality of life.