Functional correlates and prevalence of mild parkinsonian signs in a community population of older people

Background: Mild parkinsonian signs (MPS) are associated with incident dementia and an increased risk of mortality. To our knowledge, the functional correlates of MPS have not been studied. Objectives: To study the functional correlates of MPS, including self-reported and performance-based measures of function, and to determine the prevalence of MPS in a cohort of community-dwelling older people (aged greater than or equal to 65 years). Design: Participants (N = 1866) in the Washington Heights-Inwood Columbia Aging Project underwent a neurological assessment that included a modified motor portion of the Unified Parkinson's Disease Rating Scale, which yielded a parkinsonian sign score (range, 0-40) and parkinsonian sign subscores (axial function, rigidity, and tremor). A functional assessment included 3 self-reported measures of function and 2 performance-based tests. Participants with Parkinson disease were excluded. Results: Mild parkinsonian signs were present in 469 (25.1%) of the 1866 participants. The parkinsonian sign score was correlated with functional and performance-based test scores (r= 0.24-0.32, P<.001). The axial function and rigidity subscores correlated to a greater extent with functional and performance-based test scores than did the tremor subscore. In analysis of covariance models, excluding participants with dementia and adjusting for age, sex, ethnicity, education, depressive symptoms, and medical illnesses (eg, arthritis), the parkinsonian sign score and age were strongly and independently associated with functional scores. Conclusions: Mild parkinsonian signs, and particularly axial dysfunction, were associated with functional disability, including self-reported and performance-based measures of functional difficulty. Given the high prevalence of these signs in elderly persons, MPS may be a significant indicator of disability in elderly persons.