Many research studies have shown that people who exercise regularly are, on average, less likely to develop dementia. They are also more likely to have better cognitive function than those who don’t exercise. This has been found for people at middle age and also old age. Increased brain blood flow, healthier brain cells and reduced cardiovascular risk may all contribute to physical activity’s effects.
What’s the evidence that exercise reduces dementia risk?
We don’t have all the answers, but we now have good evidence that regular physical exercise can help keep your brain healthy.
Several research studies have found that regular physical activity in mid and late life is associated with a lower risk of cognitive decline and dementia. For example:
- In a study that followed 1,449 people for over 20 years, those who exercised at least twice a week at midlife were on average 52% less likely to develop dementia in old age (Rovio S, et al. Lancet Neurology, 2005; 4:705-711).
- In another study involving people aged 65 and over, exercising at least 3 times per week was associated with a 38% reduced risk of developing dementia (Larson EB, et al. Ann Intern Med, 2006; 144:73-81).
- In a recent Australian trial involving people aged 50 and over who complained of memory problems, a 6 month program of physical activity resulted in improved memory and thinking at the end of the trial and 18 months later (Lautenschlager NT, et al. JAMA, 2008; 300:1027-1037).
Regular physical exercise provides a range of other health benefits and some of these may contribute to reducing dementia risk.
- Keeps your heart and blood vessels healthy
- Reduces the risk of type 2 diabetes, high blood pressure, high cholesterol and obesity
- Improves mood
- Keeps your muscles and bones strong
Keeping your brain functioning well is another good reason to enjoy regular physical activity.
While participating in regular physical activity cannot guarantee you won’t develop dementia, the existing evidence points to regular physical exercise reducing the risk.
Many observational studies have shown an association between lower dementia risk and higher levels of regular physical activity undertaken at different stages of life.
Several intervention trials have shown that increasing physical activity can improve cognitive function or reduce cognitive decline.
What is lacking is proof that increasing the amount of exercise you do will reduce your dementia risk, but it won’t do you any harm and is good for overall health.
How does exercise reduce dementia risk?
Physical activity promotes healthy blood vessels, improving blood flow to the brain and the supply of glucose and oxygen that it needs to function well. Physical activity also promotes growth and survival of nerve cells in the brain. Human imaging studies have found that regular physical exercise is associated with less shrinkage of the brain with ageing. Animal studies have found that those who are more active have lower levels of Alzheimer’s disease pathology in their brains.
Regular physical exercise may therefore contribute to ‘brain reserve’. By helping keep the brain’s blood vessels and nerve cells healthy, physical activity helps build a reserve the brain can use to reduce the impact of diseases that cause dementia. In this way, regular physical exercise can protect against cognitive decline and dementia.
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