Good news at last: just a little exercise can reduce the risk of dementia | Devi Sridhar

A recent study shows the benefit of being a middle-aged weekend warrior' who only exercises once or twice a week

In these bleak times, glimmers of hope often seem to come out of the pages of scientific research. Take what we know about exercise. Just in the past few months, we've learned that moderate exercise may almost halve the risk of postpartum depression for new mothers, and that even five minutes of exercise a day could help lower blood pressure.

But what really caught my eye recently was a study from Latin America that included roughly 10,000 people who were assessed over two decades using the Mexico City prospective study. The research, published in the British Journal of Sports Medicine, examined cognitive function with the aim of understanding the impact of exercise on mental ability, including mild dementia. The researchers took account of confounding variables such as age, diet, smoking and alcohol intake, nightly sleep and educational attainment, which have all been shown to affect overall health and wellbeing. By controlling for these factors, the contribution of physical activity towards mild cognitive impairment was estimated.

Prof Devi Sridhar is chair of global public health at the University of Edinburgh, and the author of How Not to Die (Too Soon)