New research has identified 17 overlapping factors that affect your risk of stroke, dementia and late-life depression, suggesting that a number of lifestyle changes could simultaneously lower the risk of all three.
Though they may appear unrelated, people who have dementia or depression or who experience a stroke also often end up having one or both of the other conditions, said Dr. Sanjula Singh, a principal investigator at the Brain Care Labs at Massachusetts General Hospital and the lead author of the study. That’s because they may share underlying damage to small blood vessels in the brain, experts said.
Some of the risk factors common to the three brain diseases, including high blood pressure and diabetes, appear to cause this kind of damage. Research suggests that at least 60 percent of strokes, 40 percent of dementia cases and 35 percent of late-life depression cases could be prevented or slowed by controlling risk factors.
“Those are striking numbers,” said Dr. Stephanie Collier, director of education in the division of geriatric psychiatry at McLean Hospital in Massachusetts. “If you can really optimize the lifestyle pieces or the modifiable pieces, then you’re at such a higher likelihood of living life without disability.”
Often, the risk factors for these diseases are interconnected, and addressing one — for example, getting more exercise by going for routine walks with a friend — can also help you address others, like excess weight and social isolation.
“If you’re starting to work on one of them, very often you’re actually improving multiple at the same time,” Dr. Singh said. “That’s a great way to start.”
The factors that protect against brain disease
The study, which looked at data from 59 meta-analyses, identified six factors that lower your risk of brain diseases:
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Low to moderate alcohol intake (Consuming one to three drinks a day had a smaller benefit than consuming less than one drink a day.)
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Cognitive activity, meaning regular engagement in mentally stimulating tasks like reading or doing puzzles
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A diet high in vegetables, fruit, dairy, fish and nuts
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Moderate or high levels of physical activity
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A sense of purpose in life
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A large social network
The factors that increase your risk
The study also identified 13 health characteristics and habits that make you more likely to develop dementia, a stroke or late-life depression. (Altogether, the protective and harmful factors add up to 19 factors because two of them, diet and social connections, can increase or decrease risk, depending on their type and quality.)
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High blood pressure
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High body mass index
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High blood sugar
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High total cholesterol
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Depressive symptoms
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A diet high in red meat, sugar-sweetened beverages, sweets and sodium
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Hearing loss
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Kidney disease
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Pain, particularly forms that interfere with activity
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Sleep disturbances (for example, insomnia or poor sleep quality) or sleep periods longer than eight hours
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Smoking history
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Loneliness or isolation
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General stress or stressful life events (as reported by study subjects)
The study only looked at risk factors linked to two or more of the three conditions. It did not prove that these risk factors directly cause the diseases; it only showed an association.
Trying to tackle all of these behaviors for brain health might feel overwhelming. But Dr. Singh suggested treating the list like a menu of options: “Choose just a first risk factor and then take it step by step,” she said.
Where to begin
The study also identified which specific risk factors and protective habits have a particularly notable effect on brain health. Addressing those, doctors said, is a great place to start.
Lowering your blood pressure can have big benefits.
The study found that high blood pressure was the greatest individual risk factor for developing any of the three diseases, in large part because it nearly triples the risk of stroke.
Another new paper, this one published in Nature Medicine, offers further evidence for that point. In a randomized trial of 34,000 patients in China, researchers found that patients who significantly reduced their blood pressure were 15 percent less likely to develop dementia than those who did not.
Together, the findings suggest that getting blood pressure under control can have an outsized effect on brain health. To do this, you might start by lowering salt intake, exercising more or losing weight, said Dr. Alison Moore, chief of the division of geriatrics, gerontology and palliative care at the University of California San Diego.
But those interventions aren’t always enough, she said, especially as we age and our blood vessels stiffen. That’s when medication can help.
Flex your physical and mental muscles. Bonus points if it’s with friends.
Moderate and high physical activity substantially decreased the chances of stroke and dementia, as did having a large social network. The meta-analyses that were included defined these levels in different ways, but guidelines from the American Heart Association describe activities like walking and gardening as “moderate” intensity exercise, and running and swimming are considered “vigorous” or of high intensity.
Cognitive activity appeared to have the largest protective effect, reducing the risk of dementia by about 40 percent. But the researchers noted that this finding could be, at least in part, a result of “reverse causality” — when people who are already developing dementia do less cognitively demanding activities because of their symptoms.
Still, Dr. Collier said the data reaffirm her advice to patients to engage in mental tasks that are “a little bit difficult” — such as reading, doing puzzles or learning a new instrument. Ideally, she said, you’d do those activities with somebody else, because conversation can be cognitively stimulating and because you get the added benefit of social interaction.
Start early if you can.
Dr. Collier said the right time to start making lifestyle changes “is generally not older age — it’s middle age.” That can prevent even early disease from developing.
But taking steps to reduce these risk factors can help prevent or slow the progression of disease later in life, too. It can also benefit patients who have a family history or genetic predisposition for these diseases, who “often feel like it’s their inevitable fate,” Dr. Singh said. But “there are things they can do — we all can do — to take better care of their brains.”
