0625 Associations of Physical Activity and Hypoxic Burden with Processing Speed and Regional Tau Deposition in Older Black Adults

Abstract Introduction Physical activity (PA) is acknowledged for its positive impact on cognitive health. In contrast, obstructive sleep apnea--marked by hypoxic burden--has been linked to cognitive impairments and Alzheimer’s disease (AD) pathology. Despite their overall contributions to cognitive health, the effects of PA and hypoxic burden on processing speed and regional AD pathology, specifically tau deposition, remain unclear. To address this gap, we investigated how PA and hypoxic burden relate to processing speed and tau deposition in cognitively normal older Black adults. Methods A cross-sectional study of 51 participants (mean age: 63.1 ± 15.8 years) from NYU’s Aging Research In Sleep Equity and Dementia Prevention Program. Participants underwent neuropsychological testing, nocturnal polysomnography, clinical evaluation, tau ([18F]MK6240) and Aβ ([18]FBB) PET scans, and seven days of actigraphy to assess PA. Cognitive tasks measured processing speed via the trails A exam, while hypoxic burden was assessed using T90 or the percentage of sleep duration spent with oxygen saturation below 90%. PA was characterized as daily step count. For tau, data were analyzed from composite regions corresponding to Braak pathological stages I–VI. Multivariable regression tested PA, sleep, PET tau outcomes, cognition relationships, adjusting for age, education, sex, global amyloid burden, and BMI. Results Participants were 60.8% female, with obesity common (BMI: 30.7 ± 5.9 kg/m2), an average education level of 14.8 ± 2.4 and processing speed of 35.7 ± 13.8 seconds. Higher PA was significantly associated with faster processing speed (β=-0.24[-5.34, -0.27], p = 0.031), decreased hypoxic burden (β = -0.32[-0.62, -0.021], p = 0.036), and decreased regional tau (Braak 1; β = -0.40, p = 0.017). Increased hypoxic burden was significantly associated with slower processing speed (β = 0.32 [0.03, 0.48], p=0.030) and an increase in regional tau (Braak stage 4; β = 0.37[0.001, 0.004], p = 0.039). Conclusion Our findings highlight the significant effects of PA and hypoxic burden on processing speed and regional tau deposition in older Black adults. These results underscore the need for longitudinal studies to further explore whether interventions targeting PA can buffer the adverse cognitive and AD pathological effects of hypoxic burden. Support (if any)