Association of fatigue and other non-motor and motor symptoms in Parkinson's disease.

BACKGROUND: Fatigue is a frequent and disabling non-motor symptom in Parkinson's disease (PD), which negatively affects patients' quality of life. The objective was to explore the association between fatigue and a comprehensive panel of non-motor and motor symptoms of PD. METHODS: We conducted a cross-sectional study including 80 PD patients. Fatigue was assessed using the Fatigue Severity Scale. Demographic data, motor and non-motor symptoms were evaluated. Regression analyses were applied to analyse the impact of different variables on fatigue. RESULTS: Fatigued patients exhibited longer disease duration, higher H&Y scale scores, more severe motor symptoms affecting activities of daily living (ADLs), and higher levels of anxiety, depression, and apathy. They also presented with more severe sleep disturbances, excessive daytime sleepiness, and frontal executive dysfunction. Multiple linear regression analysis revealed that fatigue severity was independently associated with excessive daytime sleepiness (ESS) and anxiety (HAMA). Logistic regression analysis identified female gender, higher Unified PD Rating Scale Part II (UPDRS-II) scores, higher ESS and HAMA scores as independent factors associated with the presence of fatigue; higher education level was associated with a lower risk of fatigue. CONCLUSION: Non-motor symptoms have a greater impact on PD-related fatigue than motor dysfunction per se, with excessive daytime sleepiness and anxiety being the most significant independent correlates. Female gender and severe motor symptoms affecting ADLs are also associated with an increased risk of fatigue in PD patients. Prospective interventional studies are warranted to verify the potential benefit of managing these non-motor comorbidities.