Dementia Support Line
Who is most at risk of dementia?
This page is about the dementia risk factors that you cannot control, or that can be difficult to control as an individual. Understanding them can help explain why dementia affects some people more than others.
Understanding dementia risk
There are several things that affect a person’s chance of developing dementia. Some of these factors are part of who we are and cannot be changed. Our age, sex and genes make up the majority of our risk. Others are shaped by our life experiences, circumstances and environment.
Having one or more of these factors does not mean that someone will definitely develop dementia. Dementia is usually caused by a combination of factors, and there are also things we can do to reduce our risk.
You can find out about some of the most important risk factors below.
Risk factors you can't change
These are useful to know about if you want to understand your dementia risk better. You can’t change them though, which means everyone has at least some risk of dementia as they get older.
Read more about these risk factors and their connection to dementia.
Your background and living environment can also affect your risk:
Older age
By far the biggest risk factor for dementia is getter older. More than 9 out 10 people with dementia are over 70 and a typical age at diagnosis is around 80 to 85 years.
Dementia can sometimes happen in younger people, but this much less common.
Why does age increase the risk of dementia?
Dementia is caused by diseases that damage the brain, such as Alzheimer's disease. These diseases can develop slowly over many years before they cause noticeable problems with memory and thinking. As we get older, there is more time for these changes to build up in the brain.
Ageing also brings other changes that can affect brain health. Older people are more likely to have conditions such as:
- high blood pressure
- blood vessels that are twisted, leaky or blocked
- diabetes
- stroke
- and problems with the blood vessels that supply the brain.
The body's ability to recover from illness or injury can also become slower, and people become more likely to experience frailty as they get older.
Not everyone ages in the same way. Age-related changes in brain health happen faster in some people than others. Genes and the things we experience throughout life may help explain some of these differences.
Genes (inherited risk)
It’s rare for dementia to be passed down through families. When it does happen, it’s known as ‘familial dementia’. For every 100 people who get dementia, only around one of them will inherit it from a parent.
However, parents can pass on a greater risk of dementia through their genes, which is why some families have more dementia than others.
What is 'familial' dementia?
Familial dementia is when a disease gene that causes dementia is passed down from parent to child. People with familial dementia tend to develop symptoms at a much earlier age – often in their 40s.
If one parent has a disease gene that causes dementia, their child will have a 1 in 2 chance of inheriting it and developing dementia.
Most types of dementia don’t run through families like this. However, an exception to this is frontotemporal dementia, where a disease gene is involved in around 1 in 3 cases .
What are 'risk' genes?
Risk genes increase a person’s chances of developing dementia. They are much more common than familial genes. However, unlike familial genes, risk genes do not always cause a person to develop dementia. Most people with risk genes do not develop dementia.
There are many genes known to affect dementia risk. Most have a tiny effect individually, although cumulatively their combined effect can be very significant.
However, there is one risk gene called APOE that does have a big impact. Different versions of this gene result in slightly different forms of a protein that takes cholesterol around the body.
Biological sex (being born female)
Women are more likely to get dementia in their lifetime, but this is mainly because they live longer. About 2 out of 3 people with dementia are women.
Until around the age of 80, the risk of dementia is about the same between men and women. However, above this age women are more likely to have dementia. The reasons for this are still unclear. Women may be naturally more susceptible to Alzheimer’s disease, which tends to affect people around this age.
Menopause and dementia risk
Researchers are investigating whether changes in sex hormones, such as oestrogen, around menopause could affect dementia risk. Some studies suggest that going through menopause earlier may be linked to a higher risk of dementia, but the relationship between menopause, hormones and dementia is complex and we still don't fully understand it.
There is also ongoing research into whether hormone replacement therapy (HRT) affects dementia risk, but the evidence is currently mixed. HRT is not recommended specifically as a way to prevent dementia.
How your background and living environment affect your risk
Air pollution
Air pollution caused by traffic fumes and burning wood increases the risk of dementia. Burning carbon-based fuels like diesel and wood produces tiny particles called ‘PM2.5’. If these are breathed in, they can be taken up by the lungs and get into the bloodstream. From there a small proportion of these particles can get into the brain.
As well as contributing to dementia risk, this type of air pollution also contributes to other long-term conditions. For example, it is particularly bad for heart and lung health.
There are some things individuals can do to reduce their exposure, such as avoiding heavy traffic where possible or making sure homes are well ventilated when cooking with gas or using a woodburner.
However, it is not possible for everyone to avoid air pollution through individual actions. The greatest reduction in exposure is likely to come from policies and changes that improve air quality across towns and cities.
Living in a socially deprived area
People who live in more socially deprived areas have a higher risk of dementia than those living in more affluent areas.
Social deprivation means growing up and living in places where people have less access to good jobs, education, safe housing, healthy environments, and timely healthcare.
As a result, people living in the most deprived areas have higher rates of long‑term physical and mental health problems, including obesity, depression, diabetes, high blood pressure and heart disease. This then contributes to poorer brain health in older age and a higher risk of dementia.
People in socially-deprived areas also face greater barriers to dementia diagnosis and support.
Education
The education we had earlier in life can affect our risk of dementia.
Having more opportunities for education is linked with a lower risk of dementia. Education, particularly during childhood and early adulthood, can strengthen our brains, and help build 'cognitive reserve' – the brain's ability to cope with changes or damage without causing noticeable problems with memory and thinking.
People who had fewer opportunities to stay in education may have less cognitive reserve. This can mean that changes in the brain caused by dementia can affect memory, thinking and everyday activities sooner.
Access to education has not been equal for everyone. But there are things we can do later in life to support brain health and cognitive reserve.
How to reduce the risk of dementia
Making positive changes to your health and lifestyle can reduce your risk of developing dementia. The best time to start is as early as possible, as the causes of dementia take several decades to cause symptoms. However, it’s never too late to make a difference.
There are three main versions:
Everyone has two copies of the APOE gene – one from each parent. This means that we all have a genotype that’s a combination of two gene variants. For example, people with ‘E2/E2’ have the lowest dementia risk and those with ‘E4/E4’ have the highest risk.
How common is APOE4 and how much does it increase risk?
About 1 in 4 people in the UK have at least one copy of APOE4, which increases the risk of Alzheimer’s disease by around 2–3 times compared to the other versions.
Around 1 in 50 people have two copies of APOE4 (E4/E4), where they inherit one copy from each parent. This increases the risk of Alzheimer’s disease by around 8–12 times. This means having around a 50:50 chance of dementia by the age of 80.