Leading an active lifestyle, particularly before the age of 50, changes the brain in a way that could prevent dementia, according to a new study.
The findings suggest this could be down to exercise helping to preserve the volume in the area of the brain that contributes to thinking and memory, researchers said.
People who exercised throughout life were also less likely to experience cognitive decline even if they had key markers of Alzheimer’s disease, such as a build-up of the protein amyloid in the brain.
For the study, researchers analysed data from Insight46, a sub-study of the National Survey of Health and Development, which has followed 5,362 people since their birth in England, Scotland and Wales during one week in March 1946.
About 468 people – aged 70 at the time – were included in the analysis.
“When we’re thinking about brain changes, one of the biggest predictors of how big your brain volume is age," said Dr Sarah-Naomi James, who is based at the UCL Dementia Research Centre and MRC unit for lifelong health and ageing at University College London. “So the fact that we’ve got exactly the same people born in the same week takes that into account.”
The team collected information on how many times a person took part in activities such as walking, swimming, cricket, rugby and football over the course of three decades, before and after they turned 50. Brain scans taken when participants were aged 70 were then analysed.
The study found exercising throughout life was “associated with better cognitive functioning at age 70, even in those with early markers of Alzheimer’s disease”, with the benefits more pronounced in women.
People who reported exercising once or more a month before the age of 50 tended to have less shrinking in the hippocampus, the part of the brain that helps with learning and memory.
“It’s a really important part of the brain, and we’re showing that it’s actually larger," Dr James added. “We call it preservation of this area of the brain that is usually starting to decline and that is responsible for the early signs of dementia.”
The benefits of activity before the age of 50 could be linked to the intensity of exercise and the kinds of activity people were doing in their 30s and 40s, Dr James said, although more research is needed to confirm this.
While future studies may “shed light on the mechanisms of physical activity as a potential disease-modifying intervention”, Dr James said her team’s findings, published in Brain Communications, “add a little bit about the question of how, or why”.
“Why is exercise good for us? It makes intuitive sense, but we still actually don’t know lots about. We call it the mechanisms, the pathways – what is it about being physically active that is good for for our brain,” she added.
“For instance, we look at something like dementia and we say, ‘there’s a pattern that we can see replicated lots of times. People who are physically active, they’re less likely to have dementia’. But what we’re showing is that even before they have dementia, they are able to tolerate and keep their cognitive function, regardless of if they start to have the early signs in the brain.
“It might be to do this preservation of the specific area of the brain. And then also you’re able to tolerate the pathology for longer. So it means that perhaps we’re not changing the disease itself, but we’re changing perhaps when you might start to develop symptoms.”
According to Alzheimer’s Research UK, which funded the study alongside the the Medical Research Council, about 982,000 people are estimated to be living with dementia in the UK. This figure is projected to rise to more than 1.4 million in 2040.
“It’s never too late, it’s never too early. People who are active, it’s really good for your brain," Dr James said. “But actually, even if you are later in life and even starting to have disease symptoms, it could still be beneficial.”
She said she would like policies to emphasise “the importance of access to physical activity throughout the life”.
“We can think about policies around schools, which is really important, but especially thinking about throughout the life – the early 30s, when people are starting to juggle careers and families. Then thinking about the 50s, and health is changing but we need to adapt and be physically active,” Dr James said.
David Thomas, head of policy and public affairs at Alzheimer’s Research UK, said: “Dementia is not just an inevitable part of ageing, and finding ways to prevent people from ever developing it is a vital part of our mission for a cure.
“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.”
