The Relationship between Emotional Expression, Difficulty in Emotion Regulation and Anhedonia in Parkinson's Disease.

Parkinson's disease (PD), a range of neuropsychiatric symptoms, including anhedonia, depression, emotional control, and cognitive deficits, may manifest. This study aims to investigate the impact of anhedonia, emotional regulation, and emotional expression on PD. The research included 68 PD patients and 60 healthy controls. Both groups were assessed using the Hospital Anxiety and Depression Scale (HADS), Emotional Expression Scale (EES), the Short Form of the Difficulties in Emotion Regulation Scale (DERS), and the Clinician-Administered Snaith-Hamilton Pleasure Scale (SHAPS), all administered by a psychiatrist. The PD group was evaluated by a neurology specialist using the Unified Parkinson's Disease Rating Scale (UPDRS). Results showed that the PD group scored significantly higher on the HADS (p < 0.01), DERS (p < 0.01), and SHAPS (p < 0.01), while their EES scores were significantly lower (p < 0.01) compared to the control group. Further analysis indicated that a one-unit increase in anhedonia scores corresponded to a 3.125 unit rise in non-motor symptom scores and a 5.034 unit rise in motor symptom scores. The findings suggest that anhedonia is a strong predictor of both motor and non-motor symptoms in PD. The data indicate that the link between anhedonia and PD exists independently of depression and anxiety, highlighting the necessity of addressing anhedonia as a distinct symptom in PD.