Mild Parkinsonian signs are associated with lower olfactory test scores in the community-dwelling elderly

Mild Parkinsonian signs (MPS, impaired gait, rigidity, bradykinesia, rest tremor) are commonly found during the clinical examination of older people and may be a precursor to Parkinson's disease (PD) or Alzheimer's disease (AD). Marked deficits in olfaction occur in PD and AD. The objective of this study was to determine whether University of Pennsylvania Smell Test (UPSIT) scores were lower in nondemented community-dwelling elderly with versus without MPS. Nondemented persons age ≥65 years without PD in Washington Heights-Inwood, NY were evaluated with an abbreviated motor Unified PD Rating Scale and a 40-item UPSIT. Lower UPSIT and higher transformed UPSIT score (square root [UPSIT - 41]) indicated greater olfactory dysfunction. One-hundred-seventy-seven (16.4%) of 1,078 participants had MPS. Mean UPSIT scores (MPS vs. without MPS) were 24.3 ± 7.1 versus 26.4 ± 6.8, P < 0.001. In a logistic regression analysis adjusting for age and education, transformed UPSIT score was associated with MPS (OR 1.25, 95% CI 1.04-1.52, P = 0.02). In an adjusted logistic regression analysis, participants with higher transformed UPSIT scores (based on a median split) were 1.55 times more likely to have MPS than were those with lower scores (P = 0.01). Within transformed UPSIT score quartiles, the odds of having MPS were 1.0 (reference), 1.35, 2.02, and 2.20 (P < 0.05). The association with transformed UPSIT scores was similar across MPS subtypes (axial dysfunction, rigidity, tremor). MPS were associated with a mild reduction in olfactory function. These observations further support the view of MPS as a marker of emerging degenerative brain pathologies.