Apathy's hidden pathways: Psychosocial mediators of quality of life among people with early-onset Parkinson's disease

Abstract

Introduction: Apathy is a highly prevalent non-motor symptom of Parkinson's disease (PD) and a major determinant of health-related quality of life (HRQoL). Its impact may be especially pronounced in early-onset PD (EOPD), yet the psychosocial mechanisms linking apathy to HRQoL are poorly understood. This study tested whether perceived stress, meaning in life (MiL), and psychological capital (PsyCap) mediate the relationship between apathy and HRQoL. Methods: Between November 2022 and February 2023, 262 adults with self-reported EOPD (diagnosed ≤50 y) completed an online survey comprising the Apathy Evaluation Scale, Perceived Stress Scale, Multidimensional Existential Meaning Scale, 21-item Psychological Capital Questionnaire, and Parkinson's Disease Questionnaire-8. Multiple regression mediation analysis evaluated direct and indirect paths, adjusting for years since diagnosis. Results: Apathy showed no significant direct effect on HRQoL (β = .14, p = .16) but exerted significant indirect effects via perceived stress (β = .08, p < .05), MiL (β = −.16, p < .05), and PsyCap (β = .62, p < .001). The combined indirect effect (β = −.70) exceeded the total effect (β = −.56, p < .001), demonstrating full mediation. Longer disease duration independently predicted poorer HRQoL (β = −.08, p < .05). Conclusions: In EOPD, apathy impairs HRQoL predominantly through modifiable psychosocial pathways: heightened stress appraisals, diminished life meaning, and depleted positive psychological resources. Routine screening for these factors and interventions focused on stress reduction, meaning-centered coping, and PsyCap enhancement may mitigate the QoL burden of apathy and complement pharmacological and rehabilitative care. By exposing the pathways through which apathy erodes QoL, this work paves the way for precision psychosocial interventions in a domain where no evidence-based treatments currently exist.