Short bursts of exercise can lower dementia risk

Just one or two sessions of physical activity on the weekend – an exercise pattern called ‘weekend warrior’ – can just as likely lower the risk of cognitive decline, which can often precede dementia, as more frequent sessions conclude. research published online in the British Journal of Sports Medicine.

And it may also be more convenient and feasible for busy people, the researchers suggest.

Identifying potentially modifiable risk factors for dementia is important because a five-year delay in onset could halve its prevalence, they say, adding that almost all the evidence to date comes from studies in high-income countries.

They therefore relied on two sets of survey data from the Mexico City Prospective Study, the first of which took place between 1998 and 2004, and the second between 2015 and 2019.

Approximately 10,033 people (average age 51 years) completed both surveys and their responses were included in the analysis.

For the first survey, respondents were asked whether they exercised or exercised, and if so, how often per week and for how long (in minutes).

Four groups were derived from the answers: non-athletes; the ‘weekend warriors’ who exercised once or twice a week; the regularly active people who did this three or more times a week; and a combined group consisting of weekend warriors and regularly active people.

The Mini Mental State Exam (MMSE) was used to assess cognitive function at the time of the second survey. A score of 22 or less out of 30 was used to define MCI.

A total of 7945 respondents indicated that they did not exercise at all; 726 met the definition of a weekend warrior; 1362 said they trained several times a week; and 2088 made up the combined group.

During an average monitoring period of 16 years, 2400 cases of MCI were identified. The MCI prevalence was 26% among people who did not exercise; 14% among weekend warriors; and 18.5% among regularly active people.

After taking into account potentially influential factors including age, education level, smoking, nighttime sleep, diet and alcohol intake, weekend warriors were 25% less likely to develop MCI than those who did not exercise, while the regularly active people were 11% less likely to do this. . Those in the combined group were 16% less likely to do this.

When MCI was defined as an MMSE score of 23 or less, 2856 cases were identified. And MCI prevalence rose to 30% among non-exercisers, 20% among weekend warriors and 22% among the regularly active.

Compared to the non-exercisers, weekend warriors were 13% less likely to develop MCI, while the regularly active and those in the combined group were 12% less likely to do so. The results were similar for both men and women.

The researchers estimate that, in theory, 13% of cases could be avoided if all middle-aged adults exercised at least once or twice a week.

This is an observational study, so no firm conclusions can be drawn about causal factors. And the researchers acknowledge several limitations to their findings. For example, survey respondents may not have been truly representative of middle-aged adults and there were no objective measures of physical activity.

But there are several possible explanations for the apparent protective effect of exercise on brain health, they explain.

“For example, exercise can increase the concentrations of neurotrophic factors that come from the brain [molecules that support the growth and survival of neurons] and brain plasticity. Physical activity is also associated with greater brain volume, greater executive function, and greater memory,” they write.

“To our knowledge, the current study is the first prospective cohort study to demonstrate that the weekend warrior physical activity pattern and the regularly active physical activity pattern are associated with similar reductions in the risk of mild dementia,” they continue.

And they further suggest that the findings “have important implications for policy and practice, as the weekend warrior’s physical activity pattern may be a more convenient option for busy people in Latin America and elsewhere.”