0223 Temporal Correlations in Motor Activity Fluctuations and Risk of Parkinson’s Disease in Middle-to-older Aged Adults

Introduction Physiological outputs such as motor activity display complex fluctuations with a delicate pattern balanced between randomness and excessive regularity. Altered fractal patterns were observed in patients with Parkinson’s disease (PD). We examined whether perturbed motor activity fluctuation patterns are associated with the risk of developing PD in middle-to-older aged adults. Methods Actigraphy recordings (up to 7 days) were collected from more than 100,000 participants in the UK Biobank between 2013-2015. Participants were followed after actigraphy assessments for up to 7.5 years (median: 5 years). The detrended fluctuation analysis was performed to obtain a scaling exponent, α, that quantifies temporal correlations in activity fluctuations at timescales ~6-90 min: α close to 1 indicates the highest complexity or the balance between randomness and excessive regularity as observed in health young adults; deviations from 1 indicate reduced complexity — more randomness (close to 0.5) or excessive regularity or rigidity (close to 1.5) as occurred with aging or in diseases. We performed Cox proportional hazards models to examine the association of |α-1| with incident PD (ascertained by ICD-10 codes) during the follow-up while adjusting for age, sex, education, ethnicity, obesity, sleep apnea, alcohol intake, smoking status, morbidity burden, circulatory system disorder, and Townsend Deprivation Index (TDI). Results In total, 94,041 participants (56.4% females; age: 62.4±7.83 [SD], range 43.5-79.0 years) who had valid actigraphy or had no PD diagnosis at baseline were included. Among them, 290 participants (~0.3%) developed PD after 3.7±1.8 [SD] years from baseline. Older age (hazard ratio [HR] per 1 year increase=1.15, 95% CI: 1.12-1.17, p< 0.0001) and being male (HR= 2.42, 95% CI: 1.88-3.13, p< 0.0001) were associated with a higher risk of developing PD. The mean and SD of the squared root transformed |α-1| were 0.2±0.1. With a square root transform on |α-1| (to account for the right skewed distribution) and after controlling for co-variables, larger |α-1| was associated with increased risk of developing PD (for 1-SD increase, HR=1.15, 95% CI: 1.02-1.28, p=0.017; Q4 vs. Q1: HR=1.46, 95% CI: 1.05-2.04, p=0.025). Conclusion Perturbed balance between randomness and regularity in motor activity fluctuations was associated with higher PD risk. Support (if any) 5T32HL007901-25, NIH RF1AG064312, BrightFocus A2020886S.