Risk of Parkinson's disease in older people with tremor: A population-based prospective study

BackgroundTremor is prevalent among older adults and is suggested to be associated with the subsequent development of Parkinson's disease (PD). However, prospective evidence for the association is scarce.ObjectiveThis population-based prospective study aimed to estimate PD risk and to explore predictive factors for PD conversion in community-dwelling older people with tremor.MethodsThe study was based on the Beijing Longitudinal Study on Aging (BLSA) II. Tremor was assessed using a validated self-administered method. Participants without parkinsonism and with any tremor were followed for an average of 7.7 years. The standardized incidence ratio (SIR) was used to estimate the risk of developing PD in older people with tremor, with age- and sex-specific incidence rates of PD in the general Chinese population as a reference. Risk factors, prodromal symptoms, and tremor features were assessed to identify predictors for incident PD.ResultsSeventeen (8.4%) of 202 participants with tremor developed parkinsonism, including 9 (4.4%) diagnosed with PD. The presence of any tremor was associated with an increased risk of developing PD (SIR: 3.12, 95% confidence interval [CI]: 1.52-5.73). Sensitivity analyses yielded similar results. Probable REM sleep behavior disorder (RBD), identified using the RBD Questionnaire-Hong Kong, and self-report of new-onset rest tremor predicted PD conversion.ConclusionsTremor is associated with an elevated risk of PD in the general older population. Screening for RBD and monitoring the evolution of tremor characteristics using simple questionnaires may help identify individuals at high risk for PD among community-dwelling older adults with tremor.