This Much Weekly Exercise Can Slash Your Dementia Risk by 41 Percent

A new study charts in detail the relationship between physical activity and dementia risk, with significant drops in risk requiring less of a physical workout than you might think.

A team led by researchers from Johns Hopkins University in the US found that up to 35 minutes of moderate-to-vigorous physical exercise every week is associated with a 41 percent drop in dementia risk, compared to those who didn't exercise at all.

There were other encouraging findings too: even the oldest among us can reduce dementia risk by increasing our weekly activity, and even just a few minutes of exercise a week can have protective effects for brain health.

"Our findings suggest that increasing physical activity, even as little as five minutes per day, can reduce dementia risk in older adults," says Johns Hopkins epidemiologist Amal Wanigatunga.

The researchers analyzed data on 89,667 adults, with a median age of 63, across an average of 4.4 years. Data was logged using dedicated activity trackers worn on the wrist, which logged movement over time.

By also recording which participants went on to develop dementia, the researchers could link activity with dementia risk. Compared to those who did no exercise at all, dementia risk was 60 percent lower for those who did 36–70 minutes of physical activity per week, and 63 percent lower in the 71–140 minutes category.

For those who banked 140 minutes or more of physical activity per week, dementia risk was reduced by 69 percent. With so many potential factors at play, from diet to genetics, this doesn't prove direct cause and effect – but it does suggest exercise and brain health are closely linked (as we've seen in earlier studies).

These associations remained more or less the same for participants classed as frail. The researchers are keen to stress that anyone at any stage of life can get the benefits from almost any level of additional exercise.

"This suggests that even frail or nearly frail older adults might be able to reduce their dementia risk through low-dose exercise," says Wanigatunga.

So if you feel like you're not exercising as much as you should be, bear in mind that it's never too late to start. Previous research has shown that upping the amount of time you spend on the move and working out can help to reverse years of inactivity.

More research will be needed to explore why this association exists, but it makes sense that a healthier body means a healthier brain. Exercise has been shown to increase the size of areas of the brain associated with learning and remembering, for example.

"This adds to a growing body of evidence that some exercise is better than nothing, especially with regard to an aging-related disorder that affects the brain that currently has no cure," says Wanigatunga.

The research has been published in the Journal of the American Medical Directors Association.