Many of us have watched a parent or grandparent change with dementia, and quietly wondered whether the same thing is waiting for us. For a long time, the honest answer was that dementia was mostly down to age and bad luck.
That picture has changed. Age and genes still matter, and nobody can promise that any one step will prevent dementia. But researchers now think a large share of dementia cases could be prevented or pushed later in life by tackling risk factors that we can do something about.
This article explains what the latest research says, which risk factors matter most, what a major new US trial found, and practical steps you can start with, whatever your age.
What does the research say?
The most influential work in this area comes from the Lancet Commission on dementia prevention, intervention and care, a group of international experts that reviews the evidence every few years.
Its 2024 report concluded that nearly half of dementia cases worldwide might be prevented or delayed by addressing 14 modifiable risk factors across the life course. That's up from the 12 risk factors and around 40 percent estimated in its 2020 report.
It's important to understand what that figure means. It's a population estimate, based on how common each risk factor is and how strongly it's linked to dementia. It doesn't mean that any one person can cut their own risk in half. And it doesn't mean that people who develop dementia did something wrong.
The 14 risk factors
The Commission groups the risk factors by the stage of life when they seem to matter most.
Early life:
Less education
Midlife (roughly 18 to 65):
Hearing loss
High LDL ("bad") cholesterol
Depression
Traumatic brain injury
Physical inactivity
Diabetes
Smoking
High blood pressure
Obesity
Excessive alcohol
Later life (65 and over):
Social isolation
Air pollution
Untreated vision loss
High LDL cholesterol and vision loss were the two new additions in 2024. According to Alzheimer Europe's summary of the report, the Commission estimated that high midlife LDL cholesterol accounts for around 7 percent of preventable cases and untreated vision loss in later life around 2 percent.
Why these risk factors matter
Researchers think these factors affect the brain in a few different ways.
Some, like high blood pressure, diabetes, high cholesterol and smoking, damage blood vessels, including the small vessels that supply the brain.
Others, like hearing and vision loss, may reduce the stimulation the brain receives, or force it to work harder to make sense of the world. Depression and social isolation affect how active and connected someone stays. And education and lifelong learning help build what's called cognitive reserve, which may help the brain cope with damage for longer before symptoms appear.
What a major US trial found
Most of the evidence on risk factors comes from observational studies, which can show links but not prove cause and effect. That's why a trial published in 2025 got so much attention.
The U.S. POINTER study, led by the Alzheimer's Association, followed 2,111 older adults aged 60 to 79 who were at higher risk of cognitive decline. Participants were randomly assigned to one of two lifestyle programmes for two years. Both encouraged physical activity, a healthy diet, mental and social activity, and keeping an eye on heart health. One was structured, with regular group meetings, goal-setting and accountability. The other was self-guided, with much less support.
Both groups improved their cognition, and the structured group improved more. The benefits were consistent across age, sex, ethnicity, heart health and a genetic risk factor for Alzheimer's.
There's an important caveat. The trial compared two lifestyle programmes with each other, rather than against a group that made no changes. And it measured thinking skills over two years, not whether people went on to develop dementia. Even so, it's strong evidence that a practical, well-supported healthy lifestyle can help protect the ageing brain.
The finding that support and accountability made a difference is also worth noticing. Knowing what to do is only half the challenge. Keeping it up is the other half.
Practical steps you can take
The Alzheimer's Society suggests starting with the changes that feel most achievable. Here's what the evidence points to:
Move more. Regular physical activity is one of the best ways to reduce risk. It helps the heart, weight, mood and sleep. Start small and build up.
Look after your heart health. Ask your doctor to check blood pressure, cholesterol and blood sugar, and treat any problems early.
Get your hearing and eyes checked. Use hearing aids and glasses if you need them.
Don't smoke, and keep alcohol within recommended limits. It's never too late to quit smoking.
Stay socially connected. Clubs, volunteering, classes or regular catch-ups with friends all count.
Keep learning. Take up something new, whether it's a language, an instrument or a class. Activities that combine moving, thinking and socialising, like dancing, are especially good.
Look after your mental health. If you feel low for more than a couple of weeks, talk to your doctor.
Protect your head. Wear a helmet for cycling and contact sports, and reduce fall risks at home.
Sleep well. If you snore heavily or feel tired all day, ask your doctor about sleep apnoea.
Our articles on whether diet can prevent dementia and whether brain supplements work look at two common questions in more detail. And if you're wondering about vitamin D, our guide to vitamin D and dementia explains what the research does and doesn't show.
The U.S. POINTER trial found that structure and support helped people stick with healthy habits. Elli Cares offers gentle daily support: reminders for medications, appointments and routines like a walk or a glass of water, plus a simple wellbeing check-in. Family members in the care circle can encourage from a distance and see how the day is going. See how Elli supports seniors and families.
What about the risks you can't change?
Some risk factors can't be changed. Getting older is the biggest one. Genes play a part too. Our article on whether Alzheimer's is genetic explains what's known about inherited risk.
The Lancet Commission found that the potential to reduce risk remains high even for people with a higher genetic risk. So having a family history isn't a reason to give up on healthy habits. If anything, it's a reason to start.
Avoiding blame
There's an important point to make here. Not everyone has the same chance to reduce their risk. Education, income, where you live and access to healthcare all affect how easy it is to act on this advice, and some risk factors, like air pollution, are largely outside personal control. The Commission itself recommends action by governments, such as cleaner air, hearing aids and eye tests for all, alongside individual changes.
Prevention should feel empowering, not like a test someone can fail. People living with dementia didn't bring it on themselves.
It's never too early, or too late
Many of the biggest opportunities are in midlife, but it's worth acting at any age. Changes like staying active, keeping socially connected and correcting hearing and vision loss matter in later life too.
If you're already living with early cognitive changes, many of these same steps can support wellbeing and independence day to day. Our guide to living well with early-stage dementia covers practical ways to do that.
The message from the research is hopeful. Dementia isn't simply an inevitable part of ageing. Small, steady changes, made with a bit of support, can make a real difference.
