Mild Parkinsonian Signs and Incidence of Motoric Cognitive Risk Syndrome in Older Adults

Objective: We aimed to compare the incidence of motoric cognitive risk syndrome (MCR)—a pre-dementia syndrome that is identified by a combination of slowed gait speed and cognitive complaints—and previous mild parkinsonian signs (MPS) in older adults without Parkinson disease who do not have dementia. Design: Prospective cohort study. Setting and Participants: The study included community-dwelling older individuals (aged ≥65 years) who did not have MCR at baseline. Participants were assessed annually over an average follow-up period of 3.1 years. Methods: MPS were defined at baseline as the presence of any one of bradykinesia, rigidity, or rest tremor as measured by the Unified Parkinson's Disease Rating Scale. Cox proportional hazard models were used to compare incident MCR in participants with and without MPS at baseline. Results: Four hundred forty-two participants (mean age 76.0 years, 55.7% women) were included, of whom 194 (43.9%) participants had MPS [rigidity (31.5%), bradykinesia (23.2%), and rest tremor (5.9%)]. Participants with MPS were significantly older (mean age 77.4 vs 74.8, P < .001) and had lower mobility (Short Physical Performance Battery Test score 9.6 vs 10.4, P < .001) compared with participants without MPS. During the follow-up, 47 participants (10.6%) developed incident MCR. Among participants without MCR at baseline, those with MPS at baseline had a greater risk of MCR onset (adjusted hazard ratio = 4.6, 95% CI 2.2-9.3, P < .001) after adjusting for age, gender, educational years, as well as after further adjustment for vascular history (adjusted hazard ratio = 4.3, 95% CI 2.1-8.8, P < .001). The risk of developing MCR increased incrementally with the number of MPS present (adjusted hazard ratio ranging from 3.0 to 8.4). Additionally, no significant association was found between prevalent MCR and MPS at baseline (odds ratio = 1.7, 95% CI 0.9-3.3, P = .11). Conclusions and Implications: MPS predict MCR onset independent of age and cardiovascular history.