Tackling these 17 factors could cut your risk of stroke, dementia and late-life depression

Making lifestyle adjustments could help you cut the risk of developing a stroke, dementia or late-life depression all at the same time, according to new research that has identified 17 overlapping risk factors for these brain-related conditions.

Addressing even one of these risk factors, which range from high blood pressure to loneliness, can help with some of the others, researchers say. For instance, taking up biking to increase your physical activity could help with high cholesterol and high blood pressure, which are also risk factors. 

“This is actually quite a feel-good story about how much of these conditions could potentially be prevented,” Anthony Levinson, a professor at McMaster University in Hamilton, Ont., who studies brain health, told CBC News. 

“The number of people with dementia alone is expected to kind of triple by the year 2050,” he added. “So at a population and a public health level, I think it’s really important if we can reduce risks.”

Previous research has shown that addressing modifiable risk factors could stop or slow at least 60 per cent of strokes, 45 per cent of dementia and 35 per cent of late-life depression. 

Aleksandra Pikula, a vascular neurologist with the University Health Network (UHN) in Toronto and one of the authors of a new study published earlier this month, said that while we’ve known for a while about individual risk factors for these three conditions, the overlap hasn’t been closely examined before. 

“The idea was really to see how we can pull all the data that exists from meta-analysis studies to identify the shared risk factors,” said Pikula, who is also Jay and Sari Sonshine Chair in Stroke Prevention & Cerebrovascular Brain Health at the University of Toronto and UHN’s Krembil Brain Institute.

“And the idea was really to see how we can draw into insights that can guide the development of targeted interventions at the population level.”

17 modifiable risk factors

This new research, published in the Journal of Neurology, Neurosurgery & Psychiatry, looked at data from 59 studies published between 2000 and 2023 to create the list of risk factors.

Four factors were identified that lower the risk of these brain-related conditions: 

• Regular cognitive activities (such as reading or doing puzzles).
• Moderate or high levels of physical activity.
• A feeling that your life has purpose. 
• Low to moderate alcohol intake (consuming less than one drink a day showed a larger benefit than consuming one to three).

Eleven factors were associated with an increased risk: 

• High blood pressure.
• Kidney disease. 
• Smoking.
• High blood sugar.
• Poor or disrupted sleep.
• High body mass index.
• Hearing loss.
• Depressive symptoms.
• General stress or stressful life events.
• Pain.
• High cholesterol.

And two factors were identified that could have protective or detrimental impacts: 

• Diet: a diet high in vegetables, fruit, nuts, fish and dairy decreased your risks of developing a brain-related condition, but a diet high in red meat, sugary beverages, candy and excess salt increased the risk. 
• Social engagement: a large social network was found to be good for the brain, while loneliness or isolation was bad for it. 

The study included risk factors linked to at least two of the three conditions, but only looked at association, not causation. 

It’s never too late to make lifestyle changes to improve your health, Pikula said, but the best outcomes are shown when people start minimizing their risk factors in mid-life, in their 40s and 50s. 

‘Cascade of factors’

It’s no surprise that stroke, dementia and late-life depression would have so many shared risk factors, according to Levinson, as patients with one of the three often develop another later on. One type of dementia is triggered by mini strokes that kill parts of the brain tissue. 

While the “cause-effect aspect” isn’t always clear, he said, one of the underlying threads for all three conditions may be damaged blood vessels that compromise blood to the brain.  

This study found that the single most dangerous risk factor for developing any of the three conditions was high blood pressure, also known as hypertension, which can cause this type of damage. 

“It’s what we call a silent killer,” Pikula said, adding that many people aren’t aware that they have high blood pressure until it manifests as a serious problem. 

It can also be tackled with medication, and a study published last week in the journal Nature Medicine suggests this can have a measurable impact on dementia incidence. 

The study looked at roughly 34,000 patients in China, and found that those who significantly reduced their blood pressure with medication were 15 per cent less likely to develop dementia than those who didn’t. 

Other risk factors may have a biological component, but could work in tandem with other factors. Hearing loss may cause “under-stimulation of some parts of the brain,” but someone with hearing loss may also be “more likely to withdraw from social interactions,” Levinson pointed out, increasing their loneliness and limiting their cognitive stimulation. 

“You can imagine almost like a cascade of risk factors,” he said.

Which risk factors to focus on first

A list of 17 factors might be a lot to absorb, but many activities will let you address several at once. 

For instance, joining a Tai Chi class would increase your social engagement and your physical activity level, while also providing cognitive exercise through learning a new skill, Levinson said. 

Lindsay Wallace, an assistant professor at Dalhousie University who studies dementia and frailty, told CBC News that “the biggest bang for your buck in terms of preventing chronic disease is making sure you get enough physical activity.”

“Physical activity is gonna lower your cholesterol, lower your blood sugar, lower your blood pressure,” she said. “It affects all these different pathways that lead to age-related disease.”

An analysis published last fall that looked at data on more than 30,000 adults in the Canadian Longitudinal Study on Aging found that physical inactivity was the most serious risk factor for dementia at a population level, followed by hearing loss, obesity and hypertension. 

Empowering individuals to improve their health and cut down on their risk is a good outcome, but Wallace hopes these studies also spur policy changes to tackle these conditions at a population level. 

Government interventions like increasing taxes and prices on tobacco products, introducing food labelling that promotes healthier diets and supporting policies that create community spaces and programs to make physical activity and social engagement more accessible will make lasting change, she said. 

In a 2024 study Wallace co-authored, researchers laid out evidence for 26 population-level interventions, including legislative ones, such as mandating hearing protective equipment in noisy workplaces.

“It’s a lot to put the onus on individuals,” she said. “I think there has to be a structural and societal change that mirrors that.”