The Dysfunctional Autonomic Function and 'Dysfunctional' Fatigue in Drug Naïve Parkinson's Disease

Background: Fatigue is a common and disabling non-motor symptom in Parkinson's disease (PD). Autonomic dysfunction is suggested as the possible pathophysiology of fatigue, but it has not been investigated in drug-naïve PD patients. Objective: In the present study, the relationship between fatigue and autonomic dysfunction in drug-naïve PD patients was investigated. Methods: In the present study, 89 drug-naïve PD patients were analyzed. The Parkinson's disease fatigue scale (PFS) was used to divide the patients into fatigue (mean PFS≥3.3) and non-fatigue groups (mean PFS < 3.3). The autonomic function test (AFT), Scale for Outcomes in Parkinson's Disease-Autonomic (SCOPA-AUT), Unified Parkinson's Disease Rating Scale (UPDRS)-I,-II,-III, modified Hoehn and Yahr (HY) scale, Montreal Cognitive Assessment (MoCA), Parkinson's Disease Questionnaire-39 (PDQ-39), Parkinson's Disease Sleep Scale (PDSS), and Beck Depress Index (BDI) were performed in all the participants. The AFT results and clinical scales were compared using multiple logistic regression analysis. Results: The prevalence of fatigue was 23.6% (n = 21) in drug-naïve PD patients. Total SCOPA-AUT score was higher in the fatigue group than in the non-fatigue group. The fatigue group had lower inspiratory:expiratory (I:E) ratio and Valsalva ratio. The prevalence of abnormal sympathetic skin response and orthostatic hypotension (OH) was 19% and 38.1%, respectively, in the fatigue group. Regression model analysis revealed that SCOPA-AUT and OH were the most related factor of fatigue in drug-naïve PD patients. Conclusion: Autonomic dysfunction in drug-naïve PD patients was investigated using a subjective scale as well as objective tests. The results indicated that fatigue is associated with autonomic dysfunction, especially OH, in drug-naïve PD patients.