Exploring the fatigue phenomenon in individuals with Parkinson’s disease: an Italian multicenter cross-sectional study

BACKGROUND: Fatigue is a common and disabling non-motor symptom in Parkinson's disease (PD), significantly affecting patients' quality of life. However, it is often underdiagnosed due to its subjective nature and the lack of a clear definition, hindering the development of effective treatments. OBJECTIVES: This study aims to investigate the prevalence of fatigue and its associations with sociodemographic factors, disease severity, levodopa equivalent daily dosage (LEDD) and motor, non-motor, and cognitive symptoms in an Italian cohort of patients with PD. METHODS: An observational cross-sectional study was carried out in three Italian centers from January to May 2024. One hundred PD patients (H&Y ≤ 4) were assessed using validated tools: Parkinson Fatigue Scale (PFS), Fatigue Severity Scale, and Modified Fatigue Impact Scale. Motor and non-motor signs and symptoms, cognitive status, and LEDD were analyzed using non-parametric tests and Spearman's correlations. Fatigue prevalence was determined based on PFS score ≥ 3.09. RESULTS: Fatigue was present in 36% of patients, more prevalent in women and more severe in those with H&Y > 2. Fatigue correlated strongly with non-motor symptoms (MDS-UPDRS Part I; ρ > 0.6, p < 0.001) and moderately with motor complications (0.4 < ρ < 0.5, p < 0.001), but weakly with disease duration, LEDD and age (ρ < 0.3, 0.002 < p < 0.05). Significant intercorrelations among fatigue scales supported their ability to consistently measure the fatigue construct. CONCLUSIONS: Fatigue in PD is a multidimensional phenomenon influenced mainly by non-motor symptoms. Gender-specific differences and the association with disease progression underscore the need of comprehensive and integrated management strategies to address this challenging symptom.