Abstract
OBJECTIVE: Fatigue is a disabling non-motor symptom in Parkinson disease (PD). We investigated the relationship between autonomic dysfunction and fatigue in PD while accounting for possible confounding factors. METHODS: 29 subjects with PD (8F/21M; mean age 61.6±5.9; mean disease duration 4.8±3.0years), underwent clinical assessment and completed several non-motor symptom questionnaires, including a modified version of the Mayo Clinic Composite Autonomic Symptom Score (COMPASS) scale and the Fatigue Severity Scale (FSS). RESULTS: The mean modified COMPASS was 21.6±14.2 (range 1.7-44.2) and the mean FSS score was 3.3±1.6 (range 1.0-6.7). There was a significant bivariate relationship between the modified COMPASS and FSS scores (R=0.69, P<0.0001). Stepwise regression analysis was used to assess the specificity of the association between the modified COMPASS and FSS scores while accounting for possible confounder effects from other variables that were significantly associated with autonomic dysfunction. Results showed that the modified COMPASS (R(2)=0.52, F=28.4, P<0.0001) was highly associated with fatigue, followed by ESS (R(2)=0.13, F=8.4, P=0.008) but no other co-variates. Post-hoc analysis exploring the association between the different modified COMPASS autonomic sub-domain scores and FSS scores found significant regressor effects for the orthostatic intolerance (R(2)=0.45, F=21.2, P<0.0001) and secretomotor sub-domains (R(2)=0.09, F=4.8, P=0.04) but not for other autonomic sub-domains. CONCLUSIONS: Autonomic dysfunction, in particular orthostatic intolerance, is highly associated with fatigue in PD.