If you want to keep your brain sharp as you get older, exercise is key. Recent research suggests that it may be the best defence there is against Alzheimer's disease as we enter middle age. Don't worry if your joints aren't up to jogging – a brisk walk several times a week is enough to make a difference.
Why exercise is important
Medical experts have known that exercise can reduce the risk of many diseases, including type-2 diabetes and some cancers - and a new review of 39 studies suggests that staying fit may be the best way to ward off the brain's natural decline over the age of 50.
Researchers in Australia found that thinking and memory skills were improved when people worked out on a regular basis. When we exercise the brain receives a greater supply of blood, oxygen and nutrients which encourages the formation of new neurons and connections, helping to keep the brain healthy.
A study of lab mice found that exercising on a treadmill can reduce the build-up of plaques and tangles in the brain by a process called autophagy – a kind of cellular housekeeping which clears out damaged or unwanted cells and introduces new ones.
Scientists believe that stimulating this process through exercise may slow down brain cell death in people with Alzheimer's – making exercise beneficial for those with dementia.
Exercise also helps improve mood - and experts know that people who are depressed are more at risk of Alzheimer's, so it might have an indirect effect that way.
What exercise should you do?
There are two types of exercises that help the brain: aerobic (anything that gets your heart pumping and leaves you out of breath) and resistance training - lifting weights, for example.
Scientists say that aerobic exercise boosts cognitive abilities, such as thinking, reading, learning and reasoning. You don't have to go jogging or run on a treadmill. A regular brisk walk (where you can still hold a conversation) is enough to make a difference.
According to a systematic review entitled 'The effect of exercise interventions on cognitive outcome in Alzheimer's disease' from the University of Sussex, doing a brisk 30-minute walk four times a week or an hour's cycling three times a week is beneficial. If you have joint problems, swimming at a fast pace or working out on an exercise bike are good options.
It's important to do strength training as well as cardio exercise. Working the muscles has a significant effect on the brain's 'executive functions' – its memory and the brain's ability to plan and organise. Carrying heavy shopping bags is one example of strength training, or you could invest in some hand weights to use at home.
For those who can't manage more challenging forms of exercise, T'ai Chi is a good option.
How often should you exercise?
Doing moderate exercise once or twice a week is associated with better cognitive functioning – but the more exercise you do, the better the improvements.
NHS guidelines suggest doing a minimum a 150 minutes of moderate aerobic activity each week (10,000 steps a day) and exercising the major muscles on two or more days each week.
According to Dr Justin Varney of Public Health England, doing any physical activity is good for the brain and body.
"Whilst every 10 minutes of exercise provides some benefit, doing 150 minutes a week cuts the chances of depression and dementia by a third, and boosts mental health at any age. Doing both aerobic and strengthening exercises leads to a greater variety of health benefits."
Other lifestyle factors
As well as keeping fit, you can look after your brain by staying mentally active, eating a Mediterranean diet, avoiding stress, sleeping well, drinking only in moderation and not smoking.