Accelerometer-derived daily steps, cognition, and cognitive impairment in U.S. community-dwelling older adults: The...

The relationship between daily steps and brain health is relatively underexplored, with inconsistent findings regarding the number of steps that confer cognitive benefits.

We conducted cross-sectional and longitudinal analyses using data from the Physical Activity and Falls Ancillary (PAFA) study of the Atherosclerosis Risk in Communities Study (ARIC) cohort. Participants wore an ActiGraph GT3X on the hip for ≥10 h on ≥3 days in 2016-2017. Daily step counts were analyzed continuously and categorically. Cognitive functioning and its change were assessed using global and domain-specific factor scores from a neuropsychological battery. Cognitive impairment was adjudicated (mild cognitive impairment [MCI] or dementia). Regression models-adjusted for demographics, lifestyle, and chronic conditions-evaluated differences in cognitive scores, their 4-year change, and odds of cognitive impairment by step counts. Spline terms assessed nonlinearity.

Among 430 participants (mean age, 78.4 years; 59.5% female; 19% Black), the baseline mean daily steps were 3492 (SD = 1934). In adjusted cross-sectional models, higher daily steps were associated with better global cognition and executive function/processing speed. Participants in the high-stepping group (≥4025 steps) had a 0.37-point higher executive function/processing speed score (95% confidence interval [CI]: 0.17-0.55) versus the low-step group (<2449). Those in the high-step group had 54% lower odds of prevalent cognitive impairment (odds ratio [OR] = 0.46, 95% CI: 0.24-0.89) compared with the lowest group. Spline models showed better cognition with higher steps, plateauing after ≈4000. Step counts were not associated with 4-year cognitive change.

Higher daily step counts are associated with better cognitive function in older adults. Modest increases in activity, even among those who moved less (<4000 steps/day), may yield cognitive benefits, although reverse causation cannot be ruled out. Promoting achievable physical activity goals, such as step counts, could benefit older adults.