Why do some people develop dementia, while others live to a ripe old age with their mind as sharp as a 20 year old? We don’t yet know the answer to this question. What we do know is that several things affect your risk of developing dementia – your age, your genes, certain health factors and your lifestyle.
Old age is the largest risk factor for dementia
Dementia mostly affects older people, and the risk of dementia increases with increasing age. The older you are, the more likely you are to be affected by dementia. Approximately 1 in 70 people aged 65-69 have dementia. Nearly 1 in 4 people aged 85-89 have dementia.
It is rare for someone under 65 to have dementia, but it does occur at younger ages and we call this ‘younger onset dementia’.
Your genes may affect your dementia risk
People often wonder whether dementia is inherited. The answer for most of us is, no. The common forms of dementia are likely caused by a combination of genetic and environmental factors.
If you have a family history of dementia, you have a higher risk of developing it yourself compared to people with no history of dementia in their family. That doesn’t mean that you will definitely get it, just that you have a slightly increased risk.
Where does this increased risk come from? There are ‘susceptibility genes’ that we might inherit from our parents that increase the risk of developing dementia. Several susceptibility genes have been found, and there are likely to be others.
Some people with susceptibility genes will develop dementia but others won’t. And some people will develop dementia even though they don’t carry these genes. So they are just a risk factor, not a cause of dementia.
There are a few very rare forms of inherited dementia. In these families, a particular gene is passed down that directly causes dementia.
Looking after your health can reduce your dementia risk
High blood pressure, obesity, high cholesterol and diabetes are risk factors for dementia. Many studies have shown that people with one of these conditions during midlife are about twice as likely on average to develop dementia later in life. If you have more than one of these conditions, your risk is increased even more.
You can’t do anything about getting older or your genes, but you can do something about your health. See your doctor for regular health checks and follow your doctor’s treatment advice.
Smoking is associated with a higher risk of dementia, as well as heart disease and cancer. If you smoke, get help from your doctor to quit.
Keeping your weight, blood pressure, cholesterol and blood sugar at healthy levels and not smoking are important for your brain and your heart. See our Heart pages for more details.
Your lifestyle choices can reduce your dementia risk
What you eat and drink and whether you exercise your body and brain all affect your dementia risk. And you can do something about the lifestyle choices you make.
A healthy diet low in saturated fat and including lots of fruit and vegetables, drinking alcohol in moderation and regular physical exercise are all associated with a lower risk of dementia. See our Body pages for more details.
Regularly exercising and challenging your brain with mental and social activities is associated with a lower risk of dementia. See our Brain pages for more details.
Avoid Head Injury
A severe injury to the brain seems to be associated with a higher risk of developing dementia. This doesn’t mean that you will get dementia if you have suffered a serious head injury – just that your risk is greater on average than someone who hasn’t suffered a serious head injury.
It’s important to wear adequate head protection when doing certain activities such as riding a bike or motorbike, rollerblading and playing certain sports. Also play it safe when using ladders avoid falls.
Depression may also be associated with a higher risk of developing dementia. Evidence is emerging about the physical effects that depression can have on the brain. It is clearly important to identify and treat depression. Preventing new episodes of depression may be useful to brain health. Effective treatment is available, so see a health professional if concerned.
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