There was a time when cognitive decline seemed inevitable, a prophecy written in our genes. But now, research suggests dementia can be just as much a product of our environment and lifestyle. Sometimes, prophecies can be avoided — and it can be as simple as adopting a few new habits.
For instance, Doug Whitney was destined for dementia. The 75-year-old American inherited a rare genetic mutation in his PSEN2 gene, which almost always leads carriers to develop dementia by their early 50s. But Whitney remains mentally sharp and has no signs of cognitive decline, decades after the age when many of his family members have developed dementia.
While trying to figure out how Whitney escaped his fate, scientists discovered high levels of heat shock proteins in his brain, which appeared to prevent the onset of dementia. These likely accumulated over Whitney’s 20 years in the Navy, working in sweltering ship engine rooms. Similarly, frequent sauna-goers tend to have a lower risk of dementia.
As Whitney demonstrated, dementia is far from inevitable. In fact, 45 per cent of all cases can be delayed or prevented, according to the landmark 2024 Lancet Commission on Dementia Prevention, Intervention and Care — and that’s likely an underestimation. As Canada’s population ages, the number of Canadians living with dementia is expected to rise 187 per cent by 2050, underscoring the need for actionable solutions.
We asked Toronto doctors and researchers for the most effective ways of avoiding cognitive decline. Some may surprise you.
Exercise more
Exercise is the leading modifiable risk factor for dementia in Canada, according to a 2024 study. “It’s good for your heart, it’s good for your brain, it’s good for blood flow, it decreases systemic inflammation,” said Dr. Howard Chertkow, co-scientific director of Baycrest’s Kimel Family Centre for Brain Health & Wellness in Toronto. “It’s almost magic.”
Canadians tend to be a sedentary people; just 21 per cent of youth met Canada’s physical activity recommendations from 2022 to 2024, while adults spent an average 9.3 hours of each day sedentary.
“If you take anybody at any age and get them doing the Canadian recommendation of 150 minutes a week of aerobic exercise, you’re going to decrease their dementia risk,” Chertkow said.
Address hearing and eyesight loss
Hearing loss is one of the most significant risk factors for dementia, according to the 2024 Lancet commission. This likely has to do with the social isolation that can come with a reduced ability to communicate, experts say.
Nearly double the amount of people with mild hearing loss will develop dementia compared to those with normal hearing, according to the Alzheimer’s Society of the U.K. People with moderate hearing loss are three times more at risk, and those with severe hearing loss have almost five times the chance of cognitive decline.
Addressing hearing loss can help delay the onset of dementia. Hearing interventions in older adults at risk of dementia slowed down their cognitive decline by 48 per cent over three years, found a 2023 study.
Vision loss is also a significant risk factor for dementia; studies show people with vision loss are 50 per cent more likely to develop dementia than those without.
Connect with friends
Social isolation is a leading driver of dementia. Over time, chronic loneliness can be a major source of stress that raises the risk of cardiovascular and neurological disease as well as depression — another major risk factor for dementia.
“Being around friends, getting out of the house, being with people mitigates loneliness and social isolation, especially as you get older,” Chertkow said.
It also provides valuable cognitive stimulation. “Sitting with your friends arguing about politics; that’s stimulating your brain cells more than just sitting alone in the living room reading the Toronto Star.”
Take care of your heart and chronic conditions
The state of the heart and vascular health is closely tied to the brain. Having a stroke more than doubles the risk of developing dementia, while the Lancet Commission lists high blood pressure as a major modifiable risk factor for dementia.
It’s common knowledge that high levels of “bad” cholesterol can increase risk of heart attack and stroke, but it’s also linked to dementia. “LDL cholesterol, the so-called bad cholesterol, has been implicated to be directly linked with the development of dementia, even without causing a stroke,” said Dr. Roger Wong, a clinical professor of geriatric medicine at the University of British Columbia. Foods that can raise levels of LDL cholesterol include fast food, fatty meats, full-fat dairy products like cheese and bakery goods like doughnuts.
Wong noted that long-term health conditions such as high blood sugar or diabetes can also be a risk factor for dementia. Properly managing these is important to reduce your risk.
Eat well
There is evidence that certain diets can help protect your heart and brain. The MIND diet (which stands for Mediterranean-DASH Intervention for Neurodegenerative Delay) recommends focusing on leafy greens, berries, nuts, olive oil and seafood while scaling back red meat, butter and margarine, pastries and fried foods.
Researchers found sticking to the MIND diet reduced the rate of developing Alzheimer’s disease by more than 50 per cent, according to the Heart and Stroke Foundation of Canada. Even “modest adherence” to the diet led to a 35 per cent reduction.
Prioritize sleep
Sleep is critical for brain health. The brain activates its waste management system during deep sleep, flushing out toxins that accumulated during the day. Those toxins are linked to numerous brain diseases, including Alzheimer’s disease, the most common cause of dementia.
“Sleep deprivation is really toxic for the brain,” said Dr. Mireille Norris, a staff internist and geriatrician at Sunnybrook hospital and an associate professor of medicine at the University of Toronto. ”Obstructive sleep apnea is also associated with obesity — both are independent risk factors and together it amplifies the risk (of dementia).”
A 2021 study from Harvard researchers found those who slept fewer than five hours a night were twice as likely to develop dementia — and twice as likely to die — than those who slept six to eight hours a night.
Stop smoking and excessive drinking
Both smoking and “excessive” alcohol were flagged as dementia risk factors by The Lancet Commission.
Studies show drinking more than 12 standard alcoholic beverages a week can increase dementia risk by 20 per cent. The Canadian Centre for Substance Abuse and Addiction recommends consuming two or fewer standard drinks a week to avoid alcohol-related consequences.
Around the globe, 14 per cent of all Alzheimer’s disease cases are potentially attributed to tobacco smoking, according to the World Health Organization. But within 10 years of quitting smoking, the risk of developing Alzheimer’s may become equal to someone who has never smoked.
Keep pursuing education
Poor education in early childhood years is a significant risk factor for dementia. It’s well-documented that the more years of education a person has, the lower their risk of cognitive impairment or dementia down the line.
We can’t travel back in time. But we can pursue further education at any time, whether that’s pursuing a formal degree, gaining a new skill or learning a second language. “Even in middle age and later, going back to school, getting more education is beneficial,” Chertkow said.
By continuously challenging our brains and building new connections between brain cells, we’re shoring up our “cognitive reserve” — a measure of how agile our brains are at pulling together disparate skills to solve new problems and challenges. This can later serve as a buffer against cognitive decline, helping stave off some symptoms of dementia.
Find your purpose
Chertkow recommends taking up volunteering, if possible, especially after retirement. This helps with social isolation, but it can also give a sense of purpose.
“This blends into a whole other category, which we don’t know much about,” Chertkow said. “There is a spiritual element here.”
He linked purpose to a sense of meaning in your life, a sense of optimism. “All of these things seem to be part of our cognitive reserve, protecting people from dementia.”
