Stroke, dementia and late-life depression. They’re the heavy hitters of getting old – no one wants them, and yet they’re surprisingly common in our ageing population.
What’s more, there’s so much information out there nowadays that it can be difficult to know where to begin when it comes to prevention. Are these things simply genetic? Are they a consequence of our life circumstances? Or are there things you can actually do that make a difference?
A new study published in the Journal of Neurology, Neurosurgery and Psychiatry offers some hopeful answers – and a clear starting point.
The research, led by Dr Sanjula Singh, a principal investigator at Brain Care Labs, Massachusetts General Hospital and Harvard Medical School, systematically reviewed data on modifiable lifestyle factors and their link to three major brain conditions.
The team identified 17 overlapping risk factors that are associated with stroke, dementia and late-life depression – and, crucially, they’re all things that people can change.
“So these are things that everybody can do on a day-to-day basis, that people can actually change,” Singh tells BBC Science Focus in an interview. “For example, it’s things that you eat or your physical activity, or it’s taking your blood pressure medication if you’re prescribed it by a doctor. There are other factors, for example, where people live or their employment status, that we call socioeconomic status, and those are not always easy to modify. People can’t just move.”
Instead, the focus here is on factors that can be shaped by daily habits: diet, sleep, exercise, social connections, mental stimulation and more.
The 17 modifiable risk factors for brain health
Altogether, the study identified 17 overlapping factors that influence your risk of stroke, dementia and late-life depression. These include both protective behaviours and risk-enhancing ones – and some, like diet and social engagement, fall into both categories depending on quality and context.
Here’s the full list:
Protective factors:
- Low or very low alcohol intake
- Regular cognitive activity – such as reading, puzzles or learning a new skill
- A diet rich in vegetables, fruits, dairy, fish and nuts
- Moderate or high levels of physical activity
- A strong sense of belonging
- A large social network or strong social engagement
Risk-increasing factors:
- High blood pressure
- High body mass index (BMI)
- High blood sugar
- High total cholesterol
- Hearing loss
- Kidney disease or impaired kidney function
- Pain that interferes with activity
- Depressive symptoms
- A diet high in red meat, sugary drinks, sweets and sodium
- Sleep disturbances or prolonged sleep durations
- Smoking history
- Loneliness or social isolation
- Stressful life events or chronic stress
Each of these factors was linked to at least one of the three conditions in the study, but often two or three. And while some – like kidney disease or hearing loss – may not sound like brain issues on the surface, their effects can be far-reaching.
A surprising leader
To uncover the most influential risk factors, Singh’s team reviewed 182 meta-analyses published over the past two decades and selected 59 of the most robust. They then calculated the impact of each factor using disability-adjusted life years (DALYs) – a measure that captures how disabling a condition is – and assigned a normalised score to each.
One risk factor stood out above the rest: high blood pressure.
“Very often, people associate blood pressure with heart health,” Singh says, “but in our review, it came out as the most important factor for brain health as well. So check your blood pressure, know your numbers. If you have high blood pressure, go to your doctor and take your medication. If it’s prescribed to you, I think that’s probably one of the best things you can do to take better care of your brain.”
High blood pressure is known to damage small blood vessels in the brain, which may contribute to the development of all three conditions. But it’s far from the only factor that matters.
The study also highlighted kidney dysfunction, high blood sugar, depressive symptoms, poor sleep, obesity, smoking and chronic stress as significant contributors to poor brain health. And these risk factors don’t operate in isolation – they tend to cluster together, compounding the risk.
A menu of healthy choices
The good news, says Singh, is that these factors are interconnected – which means tackling one can often lead to improvements in others.
“They don’t work in silos. So if you’re improving your diet and eating less salt, you’re also likely to lower your blood pressure. That’s the beauty of it; if you’re working on one of the components, very often you’re indirectly improving some of the others.”
But that doesn’t mean you need to overhaul your life all at once. In fact, Singh cautions against trying to tackle everything simultaneously. “One thing we try to do is offer small steps, because to just throw all 17 factors at someone can be quite overwhelming. We ask people to pick their favourite one and work on that. Then, indirectly, you’ll start working on the other ones as well."
“I think the beauty of looking at this research is that it can be presented as a menu for people,” she says. “If someone really wants to start working on their physical activity, great. Who am I to say start with your diet? We’re trying to provide what we call personalised prevention, so people can take the lead on what they would like to work on first. Otherwise, you often see people improve, but then afterwards they go back to what they were doing before.”
Motivation, of course, is often the biggest hurdle. “We know from behavioural science that it can be really hard to make sustained behavioural changes.” Other factors, such as a lack of time or money to adopt a new habit, can get in the way, too.
One strategy that works? Do it with someone else. Whether it’s walking with a friend, cooking a healthy dinner with a partner, or joining a class, activities that combine social connection with lifestyle change have a greater chance of sticking.
“We highly encourage people to work out together,” Singh says, “so that you’re not only working out, but also having stronger social relationships. Or having dinner together and cooking healthy food, for example.”
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When to start
Some of these risk factors matter more during particular phases of life. Midlife high blood pressure, for example, appears to be especially damaging to long-term brain health. But that doesn’t mean there’s an age cut-off for change.
“It kind of depends on the factor,” Singh says. “For example, with high blood pressure, we see that midlife hypertension is most strongly related to the outcomes of these diseases. That being said, I don’t think you can start too early. Very often, you see that the people who develop certain habits earlier in life will keep them throughout the rest of their lives.”
And if you’re starting later? Don’t let that put you off.
“There’s not an age where you’re ‘too old’. Working on modifiable risk factors works for every age group – it doesn’t matter if you’re 20 or 80, everybody can take small steps to improve their brain health.”
A note on limitations
While the study provides a strong roadmap for prevention, it doesn’t prove cause and effect. It draws on observational studies, which can show associations but not direct causality.
As Dr Anya Topiwala, a consultant psychiatrist at the University of Oxford who was not involved in the study, pointed out in an email to BBC Science Focus: “The important limitation, however, is that the paper examines observational, not experimental studies, so the relationships between risk factors and disease cannot be assumed to be causal because of various biases.”
She offers the example of alcohol, which the study found may be protective in low-to-moderate amounts. But that could be misleading. “Individuals at socioeconomic advantage or with higher education levels are more likely to drink moderately. Such individuals are generally healthier and less likely to get diagnosed with dementia – they perform better on memory tests.”
In other words, some of the associations could be driven by other underlying variables like education, income, or access to healthcare.
A hopeful message
Still, the overall picture remains encouraging. Singh is clear: the findings are not meant to overwhelm, but to empower. “Firstly, I think this is a very hopeful paper,” she says. “There’s so much you can do that’s within your control that will lower your risk of diseases.
“To give some percentages, we know that 45 per cent of all dementias can be prevented due to modifiable risk factor control, 80 per cent of strokes and 35 per cent of late-life depression. There’s so much that we can do to keep our brains healthy and happy.”
So, whether it’s going for a walk, learning something new, checking your blood pressure or just making dinner with a friend, the message is simple: start where you can. It might do more than you think.
About our experts
Sanjula Singh is a physician-scientist and Oxford-trained epidemiologist whose work bridges clinical medicine, epidemiology, behavioural science, and global health innovation. At Massachusetts General Hospital and Harvard Medical School, she became a faculty member at only 28 years old. Singh is the founder of the Singh Lab within the Brain Care Labs, where she and her team are developing and testing scalable, evidence-based interventions to prevent stroke, dementia, and late-life depression.
Anya Topiwala qualified in medicine from the University of Oxford and subsequently pursued specialist training in older adult psychiatry. In 2017, she completed a DPhil in Psychiatry based on the MRC-funded study "Predicting MRI abnormalities with longitudinal data of the Whitehall II Substudy". In 2019, Topiwala was awarded a Wellcome Trust Clinical Research Career Development Fellowship to investigate the effect of mechanistic pathways through which alcohol consumption impacts brain health.
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