Decreased Dementia Risk Associated with Increased Daily Step Count

A daily step count of just under 10 000 may reduce the risk of developing dementia by more than 50%, according to a study published in JAMA Neurology by researchers in Denmark. The study, based on longitudinal data from more than 78 000 adults participating in the UK Biobank, found that incident dementia decreased by 25% with as few as 3800 steps per day.

“The optimal dose was estimated at 9,800 steps per day, just under the popular target of 10,000 steps," noted Borja del Pozo Cruz, PhD, and co-authors. "We found no minimal threshold for the beneficial association of step counts with incident dementia."

“We estimated the minimum dose at approximately 3,800 steps per day, which was associated with 25% lower incident dementia," the researchers added. They point to studies that have found an association between 4400 steps and mortality outcomes and add that this finding "suggests that population-wide dementia prevention might be improved by shifting away from the least-active end of the step-count distributions."

del Pozo Cruz and colleagues also found that dementia risk reduction was greater as step intensity increased, with 112 steps/minute for 30 minutes linked to the greatest impact in this study population (62% vs 50% risk reduction for 9800 daily steps).

Investigators identified 103 684 eligible adults aged 40 to 79 years from the UK Biobank with valid data from a wrist-worn accelerometer from February 2013 to December 2015. They evaluated total number of daily steps, whether the steps were incidental (<40/minute) or purposeful (≥40/minute), and the peak 30-minute step cadence (ie, mean steps/minute recorded for the 30 highest minutes of the day, which were not necessarily consecutive). The primary outcome of interest was incident dementia, both fatal and nonfatal. Dose-response associations were assessed using Spline Cox regressions, according to the study.

Findings

The final cohort for analysis numbered 78 430 participants. Mean age was 61 years and 55.3% were women. The majority of participants (96.7%) were White. During a mean follow-up period of 6.9 years, the investigators observed incident dementia in 866 participants. Dementia status was based on hospital or primary care records or was identified as an underlying contributing cause of death in registry data.

The association between daily steps and incident dementia was nonlinear, according to the study analyses. The authors report the optimal daily dose of steps, ie, the value associated with the greatest dementia risk reduction, was 9826 (HR 0.49, 95% CI 0.39-0.62)

The minimal step dose, ie, the point at which dementia risk was half of the maximum reduction, was 3826 per day (HR 0.75, 95% CI 0.67-0.83).

The optimal dose of incidental steps was 3677 steps (HR 0.58, 95% CI 0.44-0.72) and for purposeful steps, the optimal dose was 6315 steps (HR 0.43, 95% CI 0.32-0.58).

“This study represents an important contribution to step count–based recommendations for dementia prevention," the authors write. “Step count–based recommendations have the advantage of being easy to communicate, interpret, and measure and may be particularly relevant for people who accumulate their physical activity in an unstructured manner.”

They add that it may be a challenge for these people to track activity or to determine if their physical activity matches current guideline recommendations, (ie, 150 to 300 minutes/week of moderate to vigorous physical activity).

Investigators note study limitations including the observational design and the potential influence of reverse causation or unmeasured confounding. They also acknowledge that the younger age of study participants may have limited the number of dementia cases and so findings may not generalize to older populations.

Reference: del Pozo Cruz B, Ahmadi M, Naismith SL, Stamatakis E. Association of daily step count and intensity with incident dementia in 78 430 adults living in the UK. JAMA Neurol. 2022;79:1059-1063. doi:10.1001/jamaneurol.2022.2672