ABSTRACT. Background: The prodromal phase of Parkinson’s disease (PD) can last up to 20 years and is characterized by a variety of non-motor symptoms. Objective: To determine the prevalence of a selection of non-motor symptoms known to be associated with an increased risk of developing PD in a late middle-aged population-based sample and to determine their association with motor function. Methods: At a mean age of 60.3 years, 775 subjects were recruited from the Longitudinal Aging Study Amsterdam (LASA). Hyposmia, cognitive impairment, patient-reported constipation, possible REM-sleep behavior disorder, depression, and anxiety were indexed as known PD risk factors. Additionally, 1) the PD screening questionnaire, 2) four physical performance tests, and 3) a functional limitations questionnaire, were used to determine whether the presence of two or more PD risk factors was associated with reduced motor function. Results: The prevalence of single risk factors ranged between 3 and 13%. Approximately 11% of subjects had two or more
PD risk factors. Motor functioning of subjects with two or more PD risk factors was significantly worse than performance of subjects without or with a single risk factor (all p values ≤ 0.001). Conclusion: Approximately 11% of the late middle-aged population has two or more known PD risk factors. Among these subjects self-perceived PD symptoms and reduced physical performance are more prevalent, suggesting that at least some of these subjects may be in the prodromal phase of PD.
