There are two main types of Alzheimer’s. Late onset Alzheimer’s starts after age 65, and young onset Alzheimer’s affects people before age 65. Different genes can be involved in the development of the disease.
Is late onset Alzheimer's inherited?
Late onset Alzheimer’s disease affects people over the age of 65. It is caused by a combination of risk factors including our age, lifestyle, environment and risk genes. It is not caused by our genes alone.
Scientists have found versions of over 75 different risk genes that can affect someone’s likelihood of developing late onset Alzheimer’s disease.
The best understood risk gene, with the largest effect on Alzheimer’s risk is called APOE. Everyone carries two copies of the gene, one inherited from each parent.
There are three different versions:
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APOE2
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APOE3
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APOE4
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APOE2
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APOE3
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APOE4
Because we all carry two copies of APOE, there are six possible combinations we could have - for example, APOE2/APOE2 or APOE2/APOE3.
APOE2 is thought to decrease our risk of developing Alzheimer’s disease.
People may still develop Alzheimer’s disease with this version but they are more likely to develop it much later in life than those with the APOE4 version.
APOE3 is the most common version of this gene.
Past research has suggested that it is unlikely to have an effect on our risk of developing Alzheimer’s disease. Ongoing studies are looking into whether there is a link or not.
People who inherit one copy of APOE4 (roughly one in four people) are around three times more likely to develop late onset Alzheimer’s disease.
About one in 50 people inherit two copies of APOE4 – one from each parent. They may be up to 15 times more likely to develop Alzheimer’s.
People with two copies of APOE4 who develop Alzheimer’s disease are also more likely to experience symptoms much younger than those with one or no copies of this version of the gene.
However due to other factors, such as age and lifestyle, people who inherit APOE4 – from one or both parents - may still never develop the disease. And because of other the risk factors at play, people without APOE4 can also develop late onset Alzheimer’s too.
Is young onset Alzheimer's inherited?
Around one in 30 people with Alzheimer’s disease develop the condition at a younger age, usually in their 40s, 50s or early 60s.
For many cases of young onset Alzheimer’s, the cause is still unclear but is likely due to a complex interaction of genes, medical history, lifestyle and environment.
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genes
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medical history
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lifestyle
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and environment.
Some cases of young onset Alzheimer’s are caused by a faulty gene passed down in families. This is called ‘familial Alzheimer’s disease’ or ‘young onset inherited Alzheimer’s’.
It usually affects many members of the same family in every generation, typically in their 40s, 50s or 60s.
It is important to know that faulty versions of these genes are rare and account for between one and five in every 100 cases of Alzheimer’s disease.
So far, three genes that are involved in how our cells produce a protein called ‘amyloid’ have been linked to directly causing young onset inherited Alzheimer’s disease.
These genes are called:
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amyloid precursor protein (APP)
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presenilin 1 (PSEN1)
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presenilin 2 (PSEN2).
Genes and dementia
The booklet gives an overview of what genes are and how they are involved in the different diseases that cause dementia, along with information on genetic testing and current research.
Order health information
Alzheimer’s Research UK has a wide range of information about dementia. Order booklets or download them from our online form.
Dementia Research Infoline
Do you have questions about genes and dementia? Or are you keen to get involved in research studies?
Contact the Dementia Research Infoline
9am-5pm, Monday to Friday
0300 111 5 111
This information was updated in November 2024 and is due for review in November 2026. It does not replace any advice that doctors, pharmacists, or nurses may give you. Please contact us if you would like a version with references.
This information is produced with support from The Perfume Shop who had no input into the content.
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