Parkinsonism in Older Adults and Its Association With Adverse Health Outcomes and Neuropathology

Background. Mild parkinsonian signs have been documented in community-dwelling older adults without Parkinson's disease. We estimated the proportion of older adults with parkinsonism and examined its association with adverse health outcomes and indices of brain pathology. Methods. Four parkinsonian signs were assessed with the motor portion of the Unified Parkinson's Disease Rating Scale in 2,962 older adults who agreed to annual evaluation and brain autopsy. We used Cox proportional hazards models to examine the association of parkinsonism (two or more signs) and possible parkinsonism (one sign) with adverse health outcomes and regression models in 1,160 decedents to examine the association of parkinsonism and neuropathology. Results. At study entry about 25% (N = 776, 26.2%) had parkinsonism and 30% had possible parkinsonism (N = 885, 29.9%). Parkinsonism was strongly related to age. The frequency was 11.8% for people younger than 75 years, 29.1% for those aged 75- 84 years, and 43.7% for those aged 85 years or older. Parkinsonism was associated with an increased hazard of death, of mild cognitive impairment, of Alzheimer's disease and disability. Individuals with possible parkinsonism also had an increased risk for adverse health outcomes compared to individuals without parkinsonism. Postmortem indices of macroscopic and microscopic infarcts, arteriolosclerosis, and atherosclerosis were associated with parkinsonism proximate to death. Conclusions. Parkinsonism is common in older adults and is associated with an increased risk of adverse health outcomes and postmortem indices of brain pathology. Its association with age suggests that it will increase in our aging population.