The Walking "Sweet Spot" Linked To A 72% Lower Dementia Risk

I’ve become a big fan of the idea that movement doesn’t have to happen in a formal workout. A five-minute walk here, taking the stairs there, pacing around while you’re on a phone call. It all adds up.

And it does. But lately, researchers have been asking a slightly different question: Does how we accumulate that movement matter, too?

Say two people both walk for 30 minutes a day. One takes a single 30-minute brisk walk, while the other gets those same minutes in five-minute bursts throughout the day. On paper, they’ve moved the same amount. But their bodies may not experience that movement in exactly the same way.

For the study, published in Translational Psychiatry, researchers analyzed data from 66,483 adults in the UK Biobank, with an average age of 63.

Rather than asking participants to remember how much they exercised, everyone wore an accelerometer for at least five days. This allowed researchers to see not only how much people moved but how they accumulated that movement throughout the day.

They specifically looked at people's longest daily bouts of activity, including moderate-to-vigorous physical activity (MVPA), as well as how fragmented their movement was. Someone who takes one long brisk walk, for example, would have a less fragmented activity pattern than someone who moves for a few minutes, sits down, and repeats that pattern throughout the day.

Longer bouts of moderate-to-vigorous activity were associated with a lower future risk of all three conditions, even after total activity was taken into account.

For dementia, the lowest observed risk occurred at around 13 continuous minutes of moderate-to-vigorous activity, which was associated with a 72% lower risk compared with doing no MVPA. For depression and anxiety, the lowest observed risks occurred among people reaching around 36 continuous minutes of MVPA, the longest bouts observed in the analysis, corresponding to 52% and 50% lower risks, respectively.

How broken up people’s activity was also mattered. Those with the least fragmented movement patterns had an 82% lower risk of dementia, 57% lower risk of depression, and 52% lower risk of anxiety compared with those whose activity was the most fragmented.

The researchers had brain imaging available for a subset of more than 13,000 participants, which gave them another way to look at the connection.

Longer bouts of moderate-to-vigorous activity were associated with larger hippocampal volume. The hippocampus is heavily involved in learning and memory and is one of the brain regions affected by Alzheimer’s disease.

Longer bouts were also linked to fewer white matter hyperintensities, small areas of damage that are often related to changes in the brain’s blood vessels and become more common with age. More fragmented activity, meanwhile, was associated with smaller overall brain volume, smaller left hippocampal volume, and more white matter hyperintensities.

This study isn’t a reason to discount all the little ways you move throughout the day. A five-minute walk between meetings is still better than staying in your chair, and those minutes still count toward your overall activity.