Mild parkinsonian signs and plasma homocysteine concentration in community-dwelling elderly individuals.

OBJECTIVE To determine whether plasma homocysteine (Hcy) concentration is associated with mild parkinsonian signs (MPS) in community-dwelling elderly individuals. DESIGN Cross-sectional analyses of a population-based cohort study. SETTING Washington Heights-Inwood, New York. Patients Persons without dementia 65 years and older. Main Outcome Measure Participants underwent an abbreviated motor portion of the Unified Parkinson's Disease Rating Scale. Each participant was assigned an MPS score (range, 0-40). The Hcy concentration was measured from plasma. All analyses were cross-sectional. RESULTS There were 369 participants (mean +/- SD age, 77.8 +/- 6.0 years; mean +/- SD MPS score, 1.51 +/- 2.55; mean +/- SD plasma Hcy concentration, 17.3 +/- 6.5 mumol/L). Mean +/- SD MPS scores in plasma Hcy concentration quintiles were as follows: lowest quintile, 1.15 +/- 1.77; second quintile, 1.18 +/- 1.88; third quintile, 1.64 +/- 2.93; fourth quintile, 1.45 +/- 2.17; and highest quintile, 2.12 +/- 3.49 (84.3% higher than 1.15) (P = .02). In an unadjusted linear regression model, plasma Hcy concentration was associated with log MPS score (dependent variable) (P = .008). In a linear regression model that adjusted for confounding variables, plasma Hcy concentration was associated with log MPS score (P = .04). CONCLUSIONS These data indicate that MPS are associated with higher plasma Hcy concentrations. Prospective neuroimaging as well as clinical-pathological studies would further our understanding of several mechanisms that could underlie the observed association.