Individual and joint prevalence of three nonmotor symptoms of PD in the US general population

Background: Some nonmotor symptoms may precede the clinical diagnosis of Parkinson's disease (PD) by years. Methods: We examined the individual and joint prevalence of depression, daytime sleepiness, and infrequent bowel movement among 10,477 participants of the US National Health and Nutrition Examination Surveys 2005-2008. Results: For all symptoms, the prevalence was higher in women than in men. Importantly, few participants had two or more symptoms: 1.3% at ages 20 to 29, 1.0% at 30 to 39, 1.2% at 40 to 49, 3.5% at 50 to 59, 1.7% at 60 to 69, 1.1% at 70 to 79, and 1.2% at ages 80 years or older in men; the corresponding prevalence in women was 3.1%, 5.2%, 5.7%, 4.1%, 3.1%, 2.3%, and 1.2%, respectively. In both men and women, depression was correlated with infrequent bowel movement and daytime sleepiness, but the latter two were mutually independent. Conclusion: The presence of multiple nonmotor symptoms was uncommon in the general population and the prevalence was higher in women than in men.