Abstract Body: Introduction: Physical activity (PA) has been identified as a modifiable factor inversely associated with cognitive decline and dementia risk. However, most longitudinal studies to date have short follow-up and report inconsistent results on the benefit of PA to support brain health among older adults. In this study, we hypothesized that higher levels of PA measured in late life would be associated with slower rates of global and domain-specific cognitive decline and a lower risk of dementia over ~10 years in late life.

Methods: Dementia-free participants (n=5,982; mean age: 76 years; 42% male, 23% Black) who completed the interviewer-administered Modified Baecke PA Questionnaire at ARIC visit 5 (2011-2013) were included. Using the PA component of the American Heart Association’s Life’s Simple 7, participants’ PA levels were categorized as ideal, intermediate, or poor. Cognitive tests were administered at ARIC visits 5 (2011-13), 6 (2016-17), 7 (2018-19), 8 (2020), and 9 (2021-22), and were used to calculate factor scores for global cognitive function and the domains of memory, language, and executive function. Linear mixed models estimated the association of PA with change in cognitive function. Dementia cases were defined by adjudicated review, telephone interviews, informant interviews, hospitalization records, and death certificates. Dementia risk was estimated using Cox proportional hazards regression models. All models adjusted for age, sex, race-center, education, APOE-ε4 allele, smoking, hypertension, body mass index, and diabetes.

Results: Participants with ideal or intermediate PA, compared to poor PA, had slower rates of decline in global cognition, but no significant differences in rates of decline across individual cognitive domains. Over a median follow-up of 7.8 years, participants with ideal (adjusted hazard ratio [HR] = 0.62, 95% CI: 0.60, 0.67) or intermediate (adjusted HR = 0.87, 95% CI: 0.80, 0.91) PA had a reduced risk of dementia compared to participants with poor PA.

Conclusions: Higher PA levels in late life demonstrated a protective association with long-term global cognitive decline and incident dementia. Although further research with more frequent and objective measures of PA is needed to determine the duration, frequency, and intensity of PA recommended to promote brain health in older adults, our findings suggest that promoting PA among aging populations offers a non-invasive and accessible approach to support brain health.