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

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.

In the present study, the relationship between fatigue and autonomic dysfunction in drug-naïve PD patients was investigated.

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 (H&Y) 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.

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.

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.