Weekend bouts of exercise may be just as good for you as working out during the week when it comes to slowing down mental decline, researchers say.

The findings, which come a month after another study found being a weekend exercise “warrior” cuts the risk of developing more than 200 diseases, found that exercising on just one or two days reduced the risk of “mild dementia” compared to more regular workouts.

It adds to a growing body of evidence that it is not when you exercise – but the fact you are doing it – that improves health.

The study, in the British Journal of Sports Medicine, concluded: “The weekend warrior physical activity pattern may be a more convenient option for busy people around the world.”

It went on: “This study is important because it suggests that even busy people can gain cognitive health benefits from taking part in one or two sessions of sport and exercise per week.”

Researchers found that the risk of mild dementia was reduced by an average of 15% in the “weekend warriors” who exercised once or twice per week and by 10% in the “regularly active” who exercised more often.

After taking account of factors that might influence the results, such as age, smoking, sleep duration, diet and alcohol intake, the researchers suggested both exercise patterns had similar effects.

“We found that the weekend warrior physical activity pattern and the regularly active physical activity pattern were associated with similar reductions in mild dementia risks after adjustment for confounders,” they said.

“We found that around 10% of (mild dementia) cases would be eliminated if all middle-aged adults were to take part in sport or exercise once or twice per week or more often.

“To the best of our knowledge, this is the first prospective cohort study to show that the weekend warrior physical activity pattern is associated with reduced risk of mild dementia.”

Researchers, including from Colombia, Chile and Glasgow, examined two sets of survey data from the Mexico City Prospective Study for the research.

Overall, 10,033 people (average age 51) completed both surveys.

For the first survey, people were asked whether they exercised or played sports, and if so, how many times a week, and for how long during each session.

The results were split into four groups: the no exercisers; the “weekend warriors” who exercised/played sports once or twice a week; the regularly active who did so three or more times a week; and a combined group comprising weekend warriors and the regularly active.

A test called 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 describe mild cognitive impairment.

Overall, 7,945 people did not exercise at all; 726 were weekend warriors; 1,362 exercised several times a week; and 2,088 made up the combined group.

Over a follow-up of 16 years, 2,400 cases of mild cognitive impairment were identified.

The authors said there are limitations to the study, including that exercise habits were self-reported and how much people were exercising was not digitally measured, but they suggested several possible explanations for why exercise may protect the brain.

They said: “Exercise may increase brain-derived neurotrophic factor concentrations (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.”

A second study in the same journal also found that exercise of any intensity is linked to a 30% lower risk of death from any cause after a diagnosis of dementia.

Those researchers said people affected should be encouraged to keep up or start an exercise routine, especially as average life expectancy after a diagnosis of dementia may be only about four to five years.

Last month, a study of nearly 90,000 people enrolled in the UK Biobank project found that “weekend warriors” who fit a week’s worth of exercise into one or two days had a lower risk of developing more than 200 diseases compared with inactive people.

The diseases ranged from high blood pressure and diabetes to mood disorders and kidney disease.