Introduction: Although apathy is a common psychiatric symptom of Parkinson's disease (PD), there are many unknown aspects of its pathology. This study aimed to investigate the characteristics of apathy in treatment-naïve patients with early-stage PD.
Methods: Fifty treatment-naïve patients with early-stage PD were divided into 1 of 2 groups-apathetic or non-apathetic-based on Starkstein Apathy Scale (AS) scores. Cognitive function, depressive symptoms, olfactory function, and motor severity were compared between the two groups using validated assessment scales. Multiple linear regression was performed to assess the association between AS scores and clinical parameters.
Results: Apathy (AS score ≥16) was observed in 13 (26%) patients. Assessment scale scores (Beck Depression Inventory-Second Edition [p < .004]; modified Hoehn & Yahr stage [p = .039]; Unified Parkinson's Disease Rating Scale part III [p < .001]) were significantly higher in apathetic patients than in non-apathetic patients. Significant association between these scale scores and AS score was also evident (all p ≤ .001). There were no significant differences in the test scores derived from several other validated scales.
Conclusion: Apathy was observed in 26% of treatment-naïve patients with early-stage PD. Significant association between apathy and motor severity was found, suggesting that dysfunction of the dopaminergic pathway is involved in the pathology of apathy.
Keywords: Apathy; Parkinson’s disease; Starkstein Apathy Scale; depressive symptom.