Determinants of Autonomic Dysfunction in Idiopathic Parkinson's Disease

Objectives: To determine demographic or disease-related factors that may influence the severity of autonomic dysfunction in idiopathic Parkinson's disease (IPD).

Methods: 532 patients with IPD aged between 55 and 75 years were included. Severity of autonomic dysfunction was assessed using a 9-item autonomic dysfunction score (ADS). In addition, several demographic factors (e. g. age, gender, comorbidities) and disease- related (e. g. motor stage, disease duration, antiparkinsonian therapy) factors were recorded. A group of 67 age-matched healthy volunteers served as a control group. Demographic and clinical data of this cross-sectional survey were analyzed by a logistic stepwise regression model to determine independent predictors of autonomic dysfunction.

Results: IPD patients showed significantly higher ADS values than controls, even in the youngest age groups and in mild disease stages. Hoehn & Yahr (H&Y) stage, disease duration, age at onset and various therapy combinations all showed significant correlations with ADS. However, stepwise logistic regression revealed that age (OR 10.71; CI 7.17-16.0) and arterial hypertension (OR 3.05; CI 1.66-5.58) were the only independent risk factors associated with autonomic dysfunction. Linear regression indicated that ADS increases with age in controls as well as in patients, but with a significantly steeper slope in the latter.

Conclusions: Autonomic dysfunction as an inherent feature of IPD is present already in early disease stages. According to a logistic regression model, the severity of autonomic dysfunction in IPD is primarily related to demographic but not to disease-related factors. This and the differences in predictors for motor versus autonomic decline may indicate at least partly independent neurodegenerative processes.