What can increase a person's risk of dementia?
There are different types of risk factors for dementia, including medical, lifestyle and environmental factors. It is possible to avoid some risk factors, while others cannot be controlled.
What do ‘risk’ and ‘risk factor’ mean?
A person’s ‘risk’ of developing dementia is the chance that they will get it at some point in their life. Everyone has a chance of developing dementia, but some people have a greater chance than others. These people are at ‘higher risk’.
A ‘risk factor’ is something that is known to increase a person’s chances of developing a condition. For example, ageing is a risk factor for dementia.
This means a person who is aged over 75 is more likely to develop dementia than someone who is under 75.
Some risk factors for dementia cannot be reduced or avoided but many others can – especially with the right support.
Can you avoid dementia by avoiding risk factors?
It’s important to remember that a person may still get dementia if they avoid risk factors and have a ‘low risk’. This is because having a low risk only makes a person less likely to get dementia. It does not mean they will definitely avoid dementia.
Do all types of dementia have the same risk factors?
What are the risk factors for dementia?
There are several known risk factors for dementia. Some factors only slightly increase a person’s risk while others make it much more likely that the person will develop the condition.
For most people, the biggest risk factors for dementia are ageing and genes. A person’s risk of getting dementia can also be increased by their:
- gender and sex
- amount of ‘cognitive reserve’ – the brain’s ability to cope with disease
- other health conditions, if any
- lifestyle – for example, smoking and excessive alcohol use
- exposure to air pollution.
You can find information on all of these risk factors on this page.
Some risk factors for dementia can’t be avoided – for example ageing and genes. However there are lots of risk factors that can be avoided, or at least reduced – for example smoking. Around 4 in every 10 cases of dementia may be prevented by avoiding some of these risk factors.
A person can avoid some risk factors for dementia by making healthy life choices, such as not drinking too much alcohol. However, they may need wider changes to happen to avoid other risk factors – for example, effective environmental policies are needed to reduce air pollution.
The biggest risk factor for dementia is ageing. This means as a person gets older, their risk of developing dementia increases a lot.
For people aged between 65 and 69, around 2 in every 100 people have dementia. A person’s risk then increases as they age, roughly doubling every five years. This means that, of those aged over 90, around 33 in every 100 people have dementia.
Ageing is a risk factor for dementia because dementia can take a long time to develop. This is because dementia is caused by diseases that damage the brain, such as Alzheimer’s disease or vascular disease.
It can take these diseases many years to damage the brain enough to cause the symptoms of dementia. This means that the longer a person lives, the more time there is for dementia to develop.
Ageing is also a risk factor for dementia because an older person is likely to be coping with other changes and health conditions that can increase their risk. For example, an older person is more likely to have:
- high blood pressure
- blood vessels in the brain that are damaged, twisted or blocked
- a greater risk of having a stroke
- cells in the brain that aren’t as active as those of younger people
- a weaker immune system
- a slower ability to recover from injuries.
As a person ages, they will also become more physically frail over time. Along with the changes listed above, this can make a person more likely to develop problems with their thinking and memory.
Although older people are at a higher risk of dementia, younger people can still get it. At least 1 in 20 people with dementia developed the condition when they were aged under 65.
There are certain genes that may be passed down (inherited) from a parent that can affect a person’s chances of getting dementia. There are two types of these genes: ‘familial’ genes and ‘risk’ genes.
What are 'familial' genes?
Familial genes will definitely cause dementia if they are passed down from a parent to a child.
If one parent has a familial gene, their child will have a 1 in 2 chance of inheriting it and developing dementia – usually when they are in their 50s and 60s.
Familial genes are very rare for most types of dementia. However, these genes may be the cause of around 1 in 3 cases of frontotemporal dementia, which is a less common type of dementia.
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.
More than 20 risk genes have been found so far and most of them only slightly increase a person’s risk of dementia.
The most important risk gene for dementia is called apolipoprotein E (APOE). Certain versions (variants) of the APOE gene can make a person up to four times more likely to develop Alzheimer’s disease than people who don’t have this version of the gene.
However, it’s important to remember that these higher-risk versions still don’t always cause dementia. Most people with higher-risk versions of the APOE gene don’t ever develop the condition.
‘Cognitive reserve’ is a person’s ability to cope with disease in their brain. It is built up by keeping the brain active over a person’s lifetime.
The more cognitive reserve a person has, the longer it takes for any diseases in their brain to cause problems with everyday tasks. This means people with a larger cognitive reserve can delay the start of dementia symptoms for a longer period of time. People with a smaller cognitive reserve are at a higher risk of getting dementia in their lifetime.
The three most important factors that can lead to a smaller cognitive reserve are:
- leaving education early: a person who left school at an early age is more likely to have a smaller cognitive reserve than a person who stayed in fulltime education for longer or who continued learning throughout their life
- less job complexity: a person who has not used a range of mental skills during their lifetime of work – for example, memory, reasoning, problem-solving, communication and organisational skills – is more likely to have a smaller cognitive reserve
- social isolation: a person who has not interacted much with other people during their life may also have a smaller cognitive reserve.
This means these factors are also risk factors for dementia.
Whilst a lot of a person’s cognitive reserve is built up during their childhood and early adulthood, there are many things a person can do to increase their cognitive reserve later in life, such as staying mentally and socially active.
Overall, there are more women than men living with dementia. This is mostly because women tend to live longer than men (see ‘Age’ above).
The risk of getting dementia is about the same for men and women. However, women who are currently over 80 have a slightly higher risk of getting dementia than men their age.
The reasons why women over 80 have a higher risk of dementia than men over 80 are still unclear. It is possible that general differences in the lifestyles of these women and men over time have caused differences in their level of risk. For example, women currently in this age group may have had less access to education or work opportunities than men their age (see ‘Cognitive reserve’ above).
Separate to gender, there have also been concerns that levels of sex hormones around the time of menopause may affect a person’s risk of dementia. The evidence on this is still unclear.
When a person goes through the menopause, their levels of oestrogen and progesterone fall. Some research has suggested that the earlier this happens in someone’s life, the higher their risk of dementia. However, clinical trials of hormone replacement therapy (HRT, which replaces these sex hormones) have not shown any effect on the risk of developing dementia.
Until there is clearer evidence, HRT is not recommended as a way to help people reduce their risk of dementia.
A few studies have suggested that people from Black African, Black Caribbean and South Asian ethnic groups are more likely to get dementia than people from White ethnic groups. This includes a recent study of people living in London which also found that people from Black ethnic groups have the highest level of risk.
One possible reason for these differences is that people from Black African, Black Caribbean and South Asian ethnic groups in the UK are more likely to develop diabetes and cardiovascular disease (CVD) as they get older – both diabetes and CVD are important risk factors for dementia (see ‘Cardiovascular factors’ further down this page).
However, more evidence is needed to be certain that ethnicity itself is a risk factor for dementia.
Differences in risk between different ethnic groups may be caused by other factors. For example, some ethnic groups may generally have less access to education and work opportunities (see ‘Cognitive reserve’ above), and may be more likely to live in deprived areas (see below).
A deprived area is an area with limited access to basic resources and services, such as suitable housing, education and work opportunities.
People who live in deprived areas are at a higher risk of getting dementia. This may be because the lack of opportunities in these areas makes it harder for a person to get further education and to access jobs that keep a person mentally active throughout their life.
More deprived areas also tend to have higher levels of air pollution and less access to health and social care. This makes it harder for a person to manage any health problems that can lead to dementia (see ‘Health conditions and diseases’ below).
Health conditions and diseases
There are a number of health conditions and diseases that can increase a person's risk of dementia.
A cardiovascular disease (CVD) is a disease that damages the heart or makes it harder for blood to circulate around the body. CVD can greatly increase a person’s risk of developing dementia. This means that most risk factors for CVD are also risk factors for dementia.
The main CVD risk factors that are known to increase a person’s risk of
getting dementia are:
- high blood pressure
- increasingly stiff and blocked arteries (known as ‘atherosclerosis’)
- high blood cholesterol levels
- being overweight and physically unfit
- type 2 diabetes.
These factors start to have an effect during a person’s mid-life (aged 40–65), increasing their risk of developing dementia later in life. Type 2 diabetes is also an important risk factor for people in later life (over 65).
These CVD risk factors are most strongly linked to vascular dementia. This is because vascular dementia is directly caused by problems with blood supply to the brain.
However, CVD risk factors can also increase a person’s risk of developing Alzheimer’s disease.
Many people can avoid these CVD risk factors and there are many organisations who can provide support with this.
Dementia is more common in people who developed hearing problems during mid-life (aged 40–65).
This means that, if a person’s hearing worsens in mid-life, their risk of developing dementia when they are older increases. There may be several reasons for this, including:
- People with hearing problems may be more likely to withdraw from social situations and become more isolated over time. This can reduce their cognitive reserve (see 'Cognitive reserve' above).
- The effort of straining to hear things may also make it harder for other mental processes to work properly.
- The diseases that cause dementia can also affect hearing.
Studies have shown that using a hearing aid may significantly reduce a person’s risk of getting dementia. It’s important that a person gets regular hearing tests as they get older.
Traumatic brain injuries
Traumatic brain injuries (TBIs) are caused by a blow or jolt to the head – especially if the person is knocked out unconscious. TBIs can start a process in the brain where the substances that cause Alzheimer’s disease build up around the injured area.
Even if the injury happens when a person is young, it can still increase their risk of developing dementia. If the person suffers several TBIs their risk increases even more.
Serious TBIs in younger people are mostly caused by:
- road traffic accidents
- an object accidentally hitting their head
- active service in the armed forces
- some sports (particularly boxing, cycling, skiing and horse riding).
The risks related to regular but less serious physical blows to the head are still unclear, such as those in football and rugby. There is some evidence that professional football players may have a slightly higher risk of developing dementia when they get older.
However, this should be considered alongside the fact that football players generally live longer than other people.
People who have had periods of depression in their life also have a higher risk of developing dementia.
This may be because depression has harmful long-term effects on the brain and on the way a person thinks and copes with difficulties.
It’s still not clear if treating a person’s depression with antidepressants can reduce their risk of dementia. However, preventing depression from happening in the first place is likely to help.
There are many people who develop depression a few years before they get dementia. However, in these cases, it may be the development of dementia that is causing depression.
Some long-term medical conditions may cause problems with a person’s thinking and memory that can develop into dementia in severe cases.
These conditions include:
- multiple sclerosis
- rheumatoid arthritis
- kidney disease.
Down’s syndrome and other learning disabilities greatly increase a person’s risk of developing young-onset dementia, usually caused by Alzheimer’s disease.
Effects of air pollution
Certain forms of air pollution increase a person’s risk of dementia. These include very small particles from traffic fumes and from burning wood in the house, for example in a fireplace. If a person breathes in these particles, the particles may cause damage to blood vessels in the person’s brain, as well as a build-up of substances that can cause Alzheimer’s disease.
Unfortunately it is difficult for a person to reduce their exposure to polluted air. Governments need to develop better environmental policies to reduce air pollution, such as banning heating fuels that produce lots of smoke particles.
There is a lot of evidence that our lifestyle choices can affect our risk of developing dementia.
Studies show that dementia risk is lowest in people who have several
healthy behaviours in mid-life (aged 40–65). These behaviours include:
- regular mental, physical and social activity
- not smoking
- drinking alcohol only in moderation
- keeping a healthy diet.
The risk of dementia is lowest in people who do at least three of these
behaviours. Doing just one or two of these behaviours only reduces risk by a very small amount. For practical advice on reducing your risk, see our tips.
This list below explains how these lifestyle factors can increase a person’s risk of dementia.
- Physical inactivity – Physical inactivity can worsen the health of a person’s heart, lungs and blood circulation, and make it harder for them to control their blood sugar. It is closely linked to a higher risk of heart disease, stroke and type 2 diabetes, which are all risk factors for dementia .
- Smoking – Smoking damages a person’s heart, lungs and blood circulation, particularly the blood vessels in the brain. It causes harmful substances to build up in the brain that cause inflammation and prevent enough oxygen getting to nerve cells. The substances also increase a person’s risk of having a stroke, which can lead to vascular dementia.
- Unhealthy diet – Eating a diet that lacks a good range of healthy foods may increase a person’s risk of dementia. There are many possible reasons. For example, an unhealthy diet increases the risk of high blood pressure which is a risk factor for dementia. Too much salt (more than a teaspoon per day) is also linked with higher risk of dementia.
- Too much alcohol – Regularly drinking above the recommended amounts of alcohol exposes the brain to high levels of toxic substances that can damage nerve cells over time. The recommended amount of alcohol per week is 14 units, ideally spread over at least three days rather than all at once. Drinking very high levels of alcohol over a long period of time also increases a person’s risk of Korsakoff’s syndrome and alcohol-related brain damage, which increases the risk of dementia.
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