Here’s how exercise alters our brain chemistry – and could prevent dementia

Exercise helps protect your brain against ageing, according to a new study that adds to the multiple reasons to stay active.

While it’s long been known that exercise is good for our general wellbeing and health, this new data shows how physical activity can alter the brain chemistry that maintains synapses - the junctions between nerve cells. "With many societies around the world ageing at a rapid pace, such research adds to the conversation about how we can manage that process more effectively.

The fact that exercising lowers the risk of developing dementia has been shown in other studies, including one by the Kaiser Permanente Washington Health Research Institute, but this new research takes things one step further by starting to demonstrate how.

“We suggest physical activity may help build synaptic health, even at late ages,” say the researchers from the University of California, San Francisco. “Our data are the first to demonstrate a link between lifestyle behaviour, physical activity, and markers of synaptic integrity in human brain tissue.”

Staying active means the brain has more of a class of proteins that enhances the connections between neurons, according to Kaitlin Casaletto, an assistant professor of neurology and lead author on the study. The positive impact was found even in people whose brains at autopsy were “riddled with toxic proteins” that are associated with Alzheimer’s and other neurodegenerative diseases, the study found.

Exercise is often linked to better health throughout life, with the Centers for Disease Control and Prevention saying it’s one of the “best things” people can do to improve their health and is “vital for healthy ageing” because it can reduce the burden of chronic diseases.

The new data underlines the benefits of physical activity and sets out another reason to stay active in older age. The brains of most older adults accumulate toxic proteins that are the hallmarks of Alzheimer’s disease. Many scientists believe these toxins cause synapses and neurons to break down, and Casaletto’s work shows the importance of maintaining synaptic integrity to slow this process down.

Examining how we can age more healthily matters because more of us are living longer. The number of adults aged over 65 globally will double between 2025 and 2050, taking it to 1.6 billion, according to the US Census Bureau.

This will throw up a raft of challenges, as older adults are more affected by chronic ailments. It also means that cases of dementia are predicted to rise to 78 million by 2030 and 139 million by 2050, from around 55 million today, according to World Health Organization estimates.

Dementia is an umbrella term for a collection of symptoms that are caused by disorders affecting the brain and which impact memory, thinking, behaviour and emotion. The most common is Alzheimer’s disease, and other types include vascular dementia, Lewy body dementia and frontotemporal dementia.

Tackling Alzheimer's is a key focus for the World Economic Forum, which launched a campaign to increase collective action and fast-track policies, practices and partnerships to help new diagnostics and treatments.

“Dementia is now the 7th leading cause of mortality globally,” says Alzheimer's Disease International chief executive Paola Barbarino. “There is a perfect storm gathering on the horizon and governments all over the world should get to grips with it.”