Anhedonia in Parkinson’s disease: findings from the first national clinical and statistical study of motor and non-motor associations

Objective. To evaluate anhedonia severity in patients with Parkinson’s disease (PD) and examine its associations with demographic, motor, and non-motor characteristics. Material and methods. The study included 390 patients diagnosed with Parkinson’s disease. Participants were classified into two groups by anhedonia severity: without anhedonia (<3 points; 77 patients, 19.7%) and with anhedonia (≥3 points; 313 patients, 80.3%). All participants underwent comprehensive clinical and neurological evaluations. The variables analyzed included age, age at PD onset, disease duration, Hoehn and Yahr stage, rate of progression, presence of dyskinesias, Unified Parkinson’s Disease Rating Scale (UPDRS) scores I—III, total UPDRS score, Schwab-England scale, anxiety, depression, cognitive status, sleep quality, apathy, and asthenia. Statistical analyses included the Mann-Whitney test, Spearman’s correlation analysis, and multivariate linear regression with robust standard errors. Results. The cohort’s median anhedonia score was 4.0 [3.0; 6.0] points. Statistically significant correlations were identified between anhedonia and depressive symptoms (ρ=0.668; p<0.001; q<0.001), anxiety (ρ=0.277; p<0.001; q=0.001), Hoehn and Yahr stage (ρ=0.208; p<0.001; q<0.001), patient age (ρ=0.187; p<0.001; q=0.001), age at disease onset (ρ=0.145; p=0.006; q=0.025), and cognitive status (ρ=–0.199; p=0.009; q=0.028). Comparative analysis showed that patients with anhedonia had higher depression scores (9.0 [7.0; 11.0] versus 5.0 [4.0; 7.0] points; p<0.001; q<0.001), were older (68.0 [63.0; 74.0] versus 65.0 [58.0; 71.0] years; p=0.003; q=0.020), had lower cognitive status scores (23.0 [20.0; 25.0] versus 25.0 [24.0; 27.0] points; p=0.009; q=0.042), and lower sleep quality scores (12.0 [6.0; 18.0] versus 18.0 [14.8; 22.2] points; p=0.002; q=0.020). In the multivariate regression model, depressive symptoms were the only independent predictor of anhedonia severity (β=0.509; 95% CI 0.329 to 0.689; p<0.001; q<0.001). Conclusion. Anhedonia is a prevalent non-motor manifestation of PD, identified in most patients in this cohort. It is most strongly associated with depressive symptoms, which remain independently significant in multivariate analysis. Anhedonia is not directly related to motor severity, disease duration, dyskinesias, or functional independence. These results suggest that anhedonia is primarily an affective non-motor component of PD and should be specifically assessed in clinical practice.