Can genes cause dementia?

Around 1 in 4 people aged 55 years and over has a close birth relative with dementia. Find out what part genes play in dementia and how genetics can affect the risk of developing the condition.

Genetics of dementia
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It is well known that children can take after their parents – for example, in the way they look. This is partly because many of the key characteristics of a person are passed down from parents to children in their genes.

What are genes?

Genes are made from a chemical called DNA. They contain information that is needed to make proteins, which the body is built from. Humans have over 20,000 different genes. Most often, a person has two copies of each gene – one inherited from each parent.

What is a gene variant?

The same gene can differ between individuals – these are known as ‘gene variants’. These can help to explain why people are different to each other – for instance, why one person has blue eyes and another person has brown eyes.

If a gene variant increases a person's risk of developing a disease, it is known as a 'risk variant' for that disease.

How can genes cause disease?

Genes often play a role in the development of diseases. This can happen in two main ways.

How can genes cause dementia?

Most often, dementia is caused by a complex disease in which genes are only one factor. When this happens, the dementia develops as a result of many different factors. In these cases, genes do not directly cause it to develop.

It is not possible to directly inherit dementia when it is caused by a complex disease.

Dementia caused by a complex disease

Nearly all cases of dementia are the result of a complex disease. In these cases, genes may increase the risk of developing dementia, but they don’t cause it directly.

In some rare cases, dementia is caused directly by a single-gene disease.

In these cases, the dementia can be inherited from parent to child.

Dementia caused by a single-gene disease

Of the four most common types of dementia, frontotemporal dementia (FTD) is most likely to be caused by a single-gene change. 

Rare types of dementia caused by a single-gene change

There are some rarer types of dementia that are caused by a single-gene change. These types of dementia can be directly inherited from parent to child.

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