Most people with Alzheimer’s disease develop it after the age of 65, but people under this age can also develop it. This is called early-onset Alzheimer’s disease, a type of young-onset dementia.

In the UK there are over 40,000 people under the age of 65 with some form of dementia. 

Risk factors you can’t change

Age

Age is the biggest risk factor for Alzheimer’s. It mainly affects people over 65. Above this age, a person’s risk of developing Alzheimer’s disease doubles about every five years. One in six people over 80 have dementia – many of them have Alzheimer’s disease.

Gender

There are about twice as many women as men over 65 with Alzheimer’s disease. We don’t know the exact reasons for this. Possible explanations include:

• women on average live longer than men
• Alzheimer’s in women may be linked to loss of the hormone oestrogen after the menopause.

Genetic inheritance

The majority of dementia is not inherited, but this depends very much on the particular cause of dementia.

There are a very small number of families where it is clear that Alzheimer’s is being passed on through the genes from one generation to the next. This obvious pattern is very rare. In the few families where it is clear, dementia tends to develop well before the age of 65.

For most people with Alzheimer’s disease, the role of genes is not as clear. More than 20 genes are known to increase or reduce a person’s chances of developing Alzheimer’s. Someone with a parent or sibling who was diagnosed with Alzheimer’s when over 65 has a slightly higher risk of developing the disease. However, this does not mean that Alzheimer’s is inevitable, and everyone can take steps to reducing their own risk by living a healthy lifestyle. 

People with Down’s syndrome have a much higher risk of developing Alzheimer’s disease, because of a difference in their genetic makeup. 

Risk factors you can change

Lifestyle 

People who live a healthy lifestyle, especially from mid-life onwards, are less likely to develop Alzheimer’s disease.

This includes doing regular physical exercise and keeping to a healthy weight, not smoking, eating a healthy balanced diet and drinking alcohol within the limits recommended by the UK Chief Medical Officers.

Keeping physically, mentally and socially active will help to reduce the risk of developing dementia.

Health problems 

There are lots of health problems that increase a person’s risk of developing Alzheimer’s disease and vascular dementia. It’s important to keep these under control and get professional support as early as possible. They include:

• medical conditions such as diabetes, stroke and heart problems
• other physical health problems such as high blood pressure, high cholesterol and obesity in mid-life
• depression (although the evidence for this as a risk factor is not as strong).