Is Dementia Hereditary?

A common question dementia caregivers have is whether dementia is hereditary—and that’s completely understandable. The reality is that some types of dementia have a stronger genetic component than others. The good news is that most dementias are not directly inherited and are considered sporadic. This means non-genetic risk factors—such as age, environment, and lifestyle—often play a larger role in the development of dementia than genetics alone, though genetics can still influence risk.

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It’s also important to know that not all “dementia genes” are the same. They generally fall into two categories: risk genes and deterministic (causal) genes.

• Risk genes: increase the likelihood of developing dementia, but they do not guarantee it. The most well-known risk gene is APOE ε4. Carrying one or two copies of this gene raises the risk of developing dementia, but many people with APOE ε4 never develop dementia at all. Research suggests APOE ε4 contributes to roughly 20% of overall dementia risk across populations and is present in a significant portion of people with Alzheimer’s disease.
• Deterministic genes: are much rarer. They account for under 1% of all dementia cases, about 1% of Alzheimer’s disease cases, and approximately 20% of frontotemporal dementia cases. When these genes are present, they are more directly linked to disease development.

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Because of this, the type of dementia matters when considering whether it may be hereditary. But as you may have noticed, nowhere near half of dementia cases can be attributed to genetics alone. This raises an important question: why do so many people believe dementia is largely inherited, and why do so many families report multiple relatives living with some form of dementia?

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Part of the reason dementia can appear hereditary is that families often share environments, health patterns, and lifestyle factors across generations. Conditions such as heart disease, diabetes, high blood pressure, and limited access to preventive care tend to cluster in families—not always because of genetics, but because habits, resources, and exposures are shared. This can make dementia feel inherited, even when genetics are only one piece of a much larger picture.

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Many people with a family history of dementia never go on to develop it, while many people with no family history do. Genetics are only part of the story. In fact, research suggests that up to 40% of dementia cases worldwide may be delayed or prevented by addressing modifiable risk factors such as physical inactivity, diabetes, high blood pressure, obesity, hearing and vision loss, social isolation, air pollution exposure, depression, smoking, and excessive alcohol use.

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There are no guarantees when it comes to preventing dementia. At the same time, having an increased genetic risk does not automatically mean you will develop it. The most practical approach is to focus on what is within your control—prioritizing your health and supporting your overall well-being as best you can.

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If concerns about your personal risk feel heavy or persistent, it’s important to talk with a healthcare provider who can help evaluate and interpret that risk in context.

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References: 

https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors/genetics

https://www.theaftd.org/what-is-ftd/genetics-overview/

The Lancet Commission on Dementia Prevention (2024 Update)