Abstract Body: Introduction: Despite known benefits of physical activity (PA) on cognition, little is known about how cognitive decline may relate to PA patterns.

Hypothesis: We hypothesized that cognitive decline is associated with lower levels of PA and higher sedentary behaviors (SED) and differing patterns of accumulation across the week.

Methods: Data are from 700 MESA participants (ages 70.1 ± 6.7 years; 55% women) with a cognitive battery at Exam 6 (2016-18) and Exam 7 (2022-24) and a hip accelerometer (valid wear: ≥4 of 7 days with ≥10 hrs) at Exam 7. The cognitive battery included the Cognitive Abilities Screening Instrument (CASI), a global measure of cognitive function (range 0-100). We calculated change in CASI test scores (△ = Exam 7 – Exam 6). Evenson vector magnitude (VM) cutpoints for older adults were used to estimate minutes by intensity category. We used linear mixed models to examine daily patterns of steps and minutes of SED, low light intensity PA, high light intensity PA, and moderate/vigorous intensity PA (MVPA) by cognitive change. Models were adjusted for age, sex, race/ethnicity, center, education, income, employment status, obesity, hypertension, diabetes, smoking status, and Exam 6 CASI score.

Results: On average (± SD), participants spent 9.1 ± 3.2 hours in SED, 4.4 ± 1.3 hours in low light intensity PA, 2.0 ± 0.8 hours in high light intensity PA, and 45.2 ± 35.1 minutes in MVPA per day. Sunday was the least active/most sedentary day across the week (Figure). Average change (± SD) in CASI score was -1.2 ± 4.8 items. For every 1 item reduction in CASI score, there was 4.6 minutes (95% CI: 1.2, 8.0) higher SED and 95 fewer steps (95% CI: 24, 165) per day. No statistically significant interactions between cognitive change and gender or race/ethnicity with PA patterns were observed.

Conclusions: In an ethnically diverse cohort of older adults, decline in 6-year cognitive performance was associated with more sedentary time and less steps. Consequences of cognitive decline on movement suggests need to support sit less, move more strategies.