Accelerometer-measured daily steps and subjective cognitive ability in older adults: A two-year follow-up study.

There is still a paucity of longitudinal studies examining the relationships between objectively-assessed daily steps and cognitive performance in older adults. The current study aimed to explore whether there is a dose-response relationship between accelerometer-measured daily steps and subjective cognitive decline rate after 2 years in older adults. A total of 285 community-dwelling older adults (age = 74.52 ± 6.12 years, female = 55.4%) wore accelerometers for 7 consecutive days measuring daily steps in 2012. Subjective cognitive ability was measured using a Chinese version of the Ascertain Dementia 8-item Questionnaire (AD8). In total 274 (96.1%) participants completed the follow-up study in 2014. Multivariable negative binomial regression adjusted for confounders was undertaken. Daily steps were linearly related to a reduced decline rate in subjective cognitive ability after 2 years. When daily steps were categorized into groups (<3500, 3500-6999, and ≥7000 steps/day), taking approximately 3500-6999 steps/day was associated with a reduced subjective cognitive decline rate (RR = 0.57, 95% CI = 0.37-0.89) after 2 years compared with <3500 steps/day. When accruing ≥7000 steps/day, the decline rate progressively decreased further (RR = 0.43, 95% CI = 0.23-0.82). Sensitivity analyses supported the stability of these findings. These results suggest that there is an inverse dose-response association of daily steps with subjective cognitive decline rate. Even as few as 3500-6999 steps/day was associated with a lower subjective cognitive decline rate after 2 years. Accumulating ≥7000 steps/day could provide greater protection for subjective cognitive ability.