Higher cardiorespiratory fitness tied to about half the dementia risk across 2.3 million people

Researchers from the University of Manitoba and the University of Eastern Finland pooled 12 cohort studies involving 2,317,053 adults who were cognitively intact at the start. They compared the fittest and least fit groups, with fitness measured in metabolic equivalents (METs).

What they found

For dementia (9 studies, 2,276,366 participants and 47,796 cases), the top fitness group had a pooled risk ratio of 0.53 (95% CI 0.44 to 0.64) compared with the bottom group. Each 1-MET increment was associated with a risk ratio of 0.93 (95% CI 0.90 to 0.95). For cognitive impairment the risk ratio was 0.63 (95% CI 0.42 to 0.93). Four studies suggested that raising or maintaining higher fitness over time was associated with lower risk.

The nuance

These are observational studies, so people who are fitter may differ in other ways that protect the brain, and early, undiagnosed cognitive decline can lower fitness before dementia is recognized. The Alzheimer’s disease estimate (risk ratio 0.35) came from only 2 studies and was not statistically significant (95% CI 0.07 to 1.83).

Youthful take

Fitness is measurable and trainable at almost any age. Ask your physician whether a cardiopulmonary exercise test or a validated field test makes sense for you, and get cleared before starting vigorous training if you have heart, lung or joint conditions.