Associations of Accelerometer-Measured Physical Activity With Dementia, Anxiety, and Depression Among Older Adults

Background: Higher physical activity (PA) is associated with better neuropsychiatric health, but prior studies have been limited by cross-sectional designs, self-reported PA measures, and small numbers of older individuals. We examined associations between baseline and changes in accelerometer-measured moderate-vigorous PA (MVPA) with neuropsychiatric health among individuals aged ≥ 70 years in the National Health and Aging Trends Study. Methods: We used the average daily minutes of accelerometer-measured MVPA above a validated threshold of 2184 counts per minute as a continuous measure at baseline for the exposure variable. For longitudinal analyses, we categorized change in MVPA as follows: an increase of > 20 min/day over 1 year, a decrease of > 20 min/day over 1 year, and staying within 20 min/day over 1 year. Our outcomes were possible/probable dementia and anxiety or depression. Associations were estimated using confounder-adjusted logistic regressions. Results: In our survey-weighted analytic sample of 639 individuals aged ≥ 70 years, 56% were ≥ 75 years, and 53% were female. After adjusting for confounders, a 20-min/day higher baseline MVPA was significantly associated with lower odds of possible/probable dementia 1 year later (odds ratio [OR] = 0.89, 95% confidence interval [CI] = 0.83–0.96) but not with depression and anxiety symptoms. Compared to no change in PA over 1 year, an increase in MVPA by > 20 min/day was associated with decreased odds of depression and anxiety symptoms (OR = 0.06, 95% CI = 0.03–0.14) but not with possible/probable dementia. Compared to no change in MVPA over 1 year, a decrease in MVPA by > 20 min/day was associated with higher odds of possible/probable dementia (OR = 3.82, 95% CI = 1.34–10.87) but not with depression and anxiety symptoms. Conclusions: Higher and increasing MVPA over time is associated with better neuropsychiatric health in individuals aged ≥ 70 years. Future studies should prioritize evaluating detailed PA trajectories to better understand how different doses, intensities, and modalities of PA impact neuropsychiatric decline in older adults.