Prevalence, contributing factors, and clinical impact of apathy in Parkinson's disease

Apathy appears as a common neuropsychiatric symptom in Parkinson's disease (PD). This study aimed to investigate its prevalence, associated contributing factors, and clinical impact by a meta-analysis approach.

Studies published before October 2024 were retrieved from PubMed, Web of Science, and Google Scholar. Data were analyzed using STATA 12.0 software.

The pooled prevalence of apathy in PD was 37 % [95 % confidence interval (CI): 32 %-42 %]. Compared with PD patients without apathy (PD-NA), PD patients with apathy (PD-A) were older [standard mean difference (SMD) = 0.25, 95 % CI: 0.19 to 0.32], more likely to be male (SMD = 1.06, 95 % CI: 1.00 to 1.12), and had lower educational levels (SMD = -0.29, 95 % CI: -0.40 to -0.18). Clinically, PD-A showed worse motor performance with higher scores on the Unified Parkinson's Disease Rating Scale III (SMD = 0.52, 95 % CI: 0.38 to 0.66) and Hoehn and Yahr stage (SMD = 0.29, 95 % CI: 0.13 to 0.46). They also exhibit more general cognitive impairment (SMD = -0.37, 95 % CI: -0.47 to -0.27), and greater depressive symptoms (SMD = 0.88, 95 % CI: 0.70 to 1.06). Therapeutically, PD-A required increased levodopa doses (SMD = 0.20, 95 % CI: 0.07 to 0.32) and more frequent use of antidepressants (SMD = 1.64, 95 % CI: 1.15 to 2.36).

Apathy is prevalent in PD and associated with greater motor, cognitive, and emotional dysfunction. Early identification and targeted interventions for apathy would improve the disease management and enhance the quality of life for PD patients.