Is there a relationship between steps per day and risk of dementia?
We have all heard the saying, "10000 steps per day," is a key to our health goals. However, where does that number come from? And is more or less walking better? What about the rate?
A new study in the journal JAMA has looked at a very large sample of UK residents and found some interesting associations.
The article, Association of Daily Step Count and Intensity With Incident Dementia in 78 430 Adults Living in the UK, tracked individuals with a wrist-worn accelerometer and found a dose response rate that seems associated with decreased risk of dementia.
Up to 9800 (9826 to be precise) steps was associated with a 50% decreased risk
Beyond 9826 steps per day, there was an uptick, suggesting more walking was not beneficial and may, under certain conditions, be associated with increased risk of dementia
The minimum dose of 3826 steps per day was also associated with a benefit, too, about 25% risk of reduction in risk of dementia
Brisk walking, even for shorter periods, is better: The peak rate optimal dose in 30 minutes was 112 steps per minute
The real strengths of the article are the large sample size. With over 100000 participants in the biobank, and more than 78000 who were eligible for the study, we can be more confident in the real world applicability of the study. Relatively few studies have such a large sample size.
They tracked individuals over a 7 year period. Individuals were between 40 and 79 at the start of the study. Those who walked faster in their most active 30 minutes of the day showed a stronger dose relationship to the unlikelihood of developing dementia.
However, there are some limitations, too. For example, the sample size is mostly white from the UK. Also, this was a cohort study. Because of the type of study, we can't uncouple the chance that healthier people simply walk faster and more frequently, and therefore, the healthy population are also less likely to develop dementia. Ie, we can't say that walking, specifically, is going to prevent dementia.
But, certainly, walking is very beneficial and a simple but powerful form of healthy exercise. As the authors conclude:
"In this cohort study, a higher number of steps was associated with lower risk of all-cause dementia. The findings suggest that a dose of just under 10 000 steps per day may be optimally associated with a lower risk of dementia. Steps performed at higher intensity resulted in stronger associations."
This article also includes an editorial from the journal, pointing to the step rate of 112/30 minutes as an interesting metric. The editorial suggests a few things as a summary:
Brisk walking of 112 steps per minute for 30 minutes may lower risk of dementia by 62%
Taking 3800 steps per day lowered risk of dementia by 25% in this cohort
Taking up to 9826 steps per day lowered risk of dementia by 50% in this cohort
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. Published online September 06, 2022. doi:10.1001/jamaneurol.2022.2672