Study reveals how lifelong exercise could protect against dementia

A team at University College London (UCL) has found a link between regular physical activity throughout life and changes in the brain which could help protect people from developing dementia.

Understanding more about how exercise physically changes the brain could lead to new interventions that could stop it from happening in the first place.

The results are from Insight46, a study funded by Alzheimer’s Research UK and the Medical Research Council (MRC) which analyses health data collected from a unique group of volunteers from England, Scotland and Wales, born in the same week of 1946. Researchers have monitored the participants’ health throughout their lives as part of a larger, ongoing health study. Insight46 wants to see how the participants’ health across their lifetime is linked to their memory, thinking and physical brain changes in later life. The study, which began in 2015, has helped shape our understanding of how factors like heart health, education and head injury can affect the brain in old age.

Dr Sarah-Naomi James, based at the UCL Dementia Research Centre and MRC Unit for Lifelong Health and Ageing at UCL, leads on one arm of Insight46. Her team are exploring how being active could help a person become more ‘cognitively resilient’, or less likely to develop dementia. Previous studies have linked low physical activity to a higher dementia risk, but Dr James’ research begins to shed light on why this is the case.

Key results linking exercise and brain health

Dr James’ team collected information on how active people were in their leisure time across 30 years, spanning before and after they turned 50. They were interested in whether people said they did activities like sports, walking, or any other physical exercise for leisure, once a month or more.

The team then analysed brain scans taken when the participants were 70 years old, to see how physical changes in the brain were linked to their exercise habits throughout life.

Insight46 participants who reported regular exercise during leisure time before they were 50 years old tended to have a larger hippocampus, the part of the brain mainly responsible for memory. This area is often the first brain region affected in Alzheimer’s disease. Dr James’ team think that this could protect against memory loss, a symptom of dementia.

People who exercised throughout life were also less likely to experience cognitive decline, even if they had markers often seen in Alzheimer’s, such as build-up of the protein amyloid in the brain or brain shrinkage. Being active also appeared to help those with early Alzheimer’s disease markers to maintain and buffer their cognitive function, and this was particularly the case for women.

Dr James says:

“Exercise is essential for keeping our brains healthy. But we are still building a picture around what physical changes happen in the brain to protect it against dementia.

“Insight46 has given us valuable clues to what changes are happening in the brain, opening new exciting research avenues.

“More work will be crucial to fully understand how exercise, and taking part in leisure activities throughout our lives, could be a powerful tool to protect people against dementia for as long as possible.”

While these findings are exciting, this is just the beginning.  More research is needed to understand how exercise affects the brain in more detail, for example exploring what types of exercise, intensity and length of activity may have the most benefits.

Why are these findings important?

David Thomas, Head of Policy and Public Affairs at Alzheimer’s Research UK, explains why Insight46 has been such a crucial study for understanding dementia risk.

“Dementia is not an inevitable part of aging, and finding ways to prevent people from ever developing it is a vital part of our mission for a cure. Studies like Insight46 have highlighted not just what factors influence brain health, but also at what point in a person’s life these factors have the most impact.”

“In fact, research has shown that nearly half of dementia cases can be prevented or delayed by addressing health and lifestyle risk factors. This means there are things that all of us can do to reduce our risk, such as keeping physically active.

“While there is no sure-fire way to prevent dementia, there are some things within our control that can reduce our risk, including keeping active and looking after our heart health, challenging our brains and keeping connected to the people around us. The evidence shows that it’s never too early or late to start making positive changes.”

Studies like Insight46 have also influenced our Think Brain Health campaign, which is raising the awareness of dementia risk factors. In 2023, Alzheimer’s Research UK launched the Think Brain Health Check-In – an online quiz where people can see what simple steps they can take to reduce their risk of dementia. Over 300,000 people have since completed the Check-In to find out how they can look after their brain health.

It’s not too late to look after our brain health

Dr James’ findings from Insight46, alongside other studies, highlight that it’s never too early or late to start looking after our brain health.

Alzheimer’s Research UK supporter Graham Kent, 74, has a particular motivation for looking after his health. His wife, Marie, was diagnosed with Alzheimer’s in 2019 so Graham is determined to exercise regularly to help reduce his risk of dementia.

Graham says: “Because of Marie’s Alzheimer’s, I want to make sure I’m around for as long as possible to look after her. Part of that means staying fit and active to help keep my brain healthy.

“The first thing I do in the morning is go out for a run with our dog. And I train with a friend at least once a week. It’s great to run with people because you keep each other accountable and stay connected with them at the same time.

“Running is good fun because I know that every time I’m exercising, it’s good for my heart and my brain. I can’t control getting older, which I know increases a person’s risk of getting dementia, but I know that I can exercise regularly to help keep my brain healthy for as long as possible.”

To find out more about simple steps we can all take to reduce our dementia risk, you can take part in our Think Brain Health Check-In.

Studies like Insight46 are only possible because of volunteers willing to participate in research towards a cure. Find out more about taking part in research.

If you have any questions about dementia risk factors or taking part in research, please contact our Dementia Research Infoline on 0300 111 5 111 infoline@alzheimersresearchuk.org.