Just 5 minutes of daily exercise greatly reduces dementia risk

By Stephen Beech

Just five minutes of light exercise a day leads to "big reductions" in dementia risk among frail older people, according to a new study.

A little movement can help prevent the debilitating neurological condition - even for the elderly, say scientists.

American researchers found that engaging in as little as 35 minutes of "moderate to vigorous" physical activity per week, compared to none, was associated with a 41% lower risk of developing dementia over an average four-year follow-up period.

Greater activity was associated with lower risks - even for frail older adults, according to the findings published online in the Journal of the American Medical Directors Association.

The research team found dementia risk decreased with higher levels of physical activity.

Dementia risks were 60% lower in participants in the 35 to 69.9 minutes of physical activity per week category; 63% lower in the 70 to 139.9 minutes per week category; and 69% lower in the 140 and over minutes per week category.

The research team analyzed data from nearly 90,000 adults living in the U.K. who wore smart watch-type activity trackers.

Study lead author Dr. Amal Wanigatunga, of Johns Hopkins Bloomberg School of Public Health, Baltimore, said: “Our findings suggest that increasing physical activity, even as little as five minutes per day, can reduce dementia risk in older adults.

“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.”

Dementia, usually in the form of Alzheimer’s disease, affects millions of older people around the world.

Although the risk of dementia rises with age, research in recent years has suggested that it is somewhat preventable by lifestyle changes that include better control of cholesterol, blood pressure and blood sugar, and being more active.

But the minimum amount of activity needed to reduce dementia risk meaningfully isn’t yet clear.

The NHS in the UK and the U.S. Department of Health and Human Services both recommend that adults get at least 150 minutes of moderate-intensity exercise per week, an average of 20 minutes per day.

But for many older people, especially the frail, large amounts of exercise recommended in official guidelines are unattainable and may discourage doing any exercise at all.

For the new study, the research team analyzed data on British adults from the UK Biobank project, a long-running, ongoing study involving around 500,000 people.

The figures used in the study covered 89,667 adults, mostly in their 50s and older, who used wrist-worn accelerometers to track their physical activity for a week during the period from February 2013 to December 2015.

The research team continued to monitor their health for an average of 4.4 years, through to November 2021, during which 735 of the participants were diagnosed with dementia.

The analysis compared participants whose trackers showed some weekly moderate to vigorous physical activity to those whose trackers showed none and accounted for age and other medical conditions.

The researchers said the associations between higher activity and lower dementia risk were "striking".

Participants in the lowest activity category, ranging from one to 34.9 minutes per week, had an apparent risk reduction of about 41%.

When the research team took into account participants who met their definitions of frailty or “pre-frailty,” they found that the association between more activity and less dementia was essentially unchanged.

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

To check the possibility that their findings reflected undiagnosed dementia leading to lower physical activity, the researchers repeated their analysis but excluded dementia diagnoses in the first two years of follow-up.

However, the association between more activity and lower dementia risk remained robust.

Dr. Wanigatunga and his colleagues recommend that future clinical trial-type studies investigate "low-dose exercise" as an important initial step toward increasing physical activity as a way of preventing dementia.