Determinants of autonomic dysfunction in idiopathic Parkinson's disease

Objectives: To determine factors, such as age, motor stage, disease duration, therapy and comorbidities which 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 score (ADS). In addition, several demographic (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 or in early disease stages. Although Hoehn & Yahr (H&Y) stage, disease duration, age at onset and various therapy combinations showed significant correlations with ADS, stepwise logistic regression revealed that age was the predominant factor (odds ratio: 10.711) independently associated with higher ADS values. 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. The severity of autonomic dysfunction in IPD is primarily related to the patient's age, whereas the severity of motor symptoms was not associated with autonomic dysfunction. This and the differences in predictors for motor versus autonomic decline may indicate at least partly independent neurodegenerative processes.