Longitudinal Estimation of Adequate Physical Activity Levels to Reduce the Risk of Alzheimer's Disease and Other Dementias in Older Adults With Mild Cognitive Impairment.

Background: Although previous studies have identified a positive relationship between physical activity (PA) participation and cognitive function in older adults, further research is needed to determine the level of PA necessary to significantly reduce the risk of Alzheimer's disease and related dementias (AD/ADRD), particularly among older adults with mild cognitive impairment.

Methods: This study used Health and Retirement Study data from 2012 to 2020 (n = 9714 Index = 5) and employed the generalized estimating equations to estimate the odds ratios (OR) of AD/ADRD across various PA levels. Covariates such as age, sex, education, and baseline cognitive function in 2012 were included in the regression model.

Results: Individuals with a PA level of 2.80 experienced a 4.6% reduction in the odds of developing AD/ADRD (B = -0.046, OR = 0.954, 95% CI, 0.946-0.964). Similar significant effects were observed at PA levels of 2.60, 2.40, and 2.20, with ORs of 0.962, 0.967, and 0.970, respectively, all within 95% CI. These findings indicate that maintaining a PA level between 2.20 and 2.80 is significantly associated with a reduced risk of AD/ADRD. Lower PA levels such as 2.00 (OR = 0.974, P = .09) and 1.80 (OR = 0.983, P = .06) showed nonsignificant trends toward risk reduction.

Conclusion: Engaging in PA (eg, walking, exercise) more than twice per week significantly reduces the risk of AD/ADRD, whereas less frequent activity showed no statistically significant benefit.