Better Fitness Linked to Much Lower Risk of Depression and Dementia

It is easy to think of fitness as being about the body — but a large new analysis underscores how deeply it shapes the mind as well. Published in Nature Mental Health in April 2026, the study pooled data from 27 long-term cohort studies covering more than four million people of all ages, making it one of the most comprehensive looks yet at how cardiorespiratory fitness relates to mental health.

The associations were strong and consistent. People with higher cardiorespiratory fitness — a measure of how well the heart, lungs and muscles use oxygen during exercise — had a 36% lower risk of depression and a 39% lower risk of dementia compared with those with low fitness. Higher fitness was also linked to a 29% lower risk of psychotic disorders, while the link with anxiety was smaller and not statistically significant.

“Published in Nature Mental Health in April 2026, the study pooled data from 27 long-term cohort studies covering more than four million people of all ages, making it one of the most comprehensive looks yet at how cardiorespiratory fitness relates to mental health.”

Crucially, the benefits did not appear to be reserved for elite athletes. Even modest improvements mattered: the researchers estimated that a single increase in fitness, measured in metabolic equivalents (METs), was associated with about a 5% lower risk of depression and a 19% lower risk of dementia. "Our study emerged from a growing interest in understanding mental health from a broader, preventive perspective," said researcher Dr Bruno Bizzozero-Peroni, framing fitness as something people can build at a population level.

The usual caution applies: these are observational associations, so the analysis cannot fully prove that fitness itself causes the lower risk, and factors like baseline health and lifestyle play a role. But the sheer scale of the data and the consistency across conditions make the message compelling and empowering — improving fitness, even gradually, may be one of the most accessible ways to protect both heart and mind over a lifetime.