Is Alzheimer's Hereditary?
Alzheimer’s disease is a complex condition influenced by multiple factors, but two stand out as the most significant: age and genetics. Age is the greatest known risk factor — the likelihood of developing Alzheimer’s increases sharply after the age of 65.¹ While genetics doesn’t guarantee someone will develop the disease, researchers continue to study the role our DNA plays in triggering or accelerating its onset.²
Family history is important but not definitive. Having a first-degree relative with Alzheimer’s, such as a parent or sibling, raises your risk by around 30%.³ This is a relative increase — it means your risk grows compared to someone without family history, not that you are certain to develop the condition. And even carrying known genetic variants linked to Alzheimer’s, like those in the APOE gene, does not guarantee the disease will appear.⁴
Instead of a single cause, Alzheimer’s is believed to result from a combination of small changes in several genes. A major study published in Nature Genetics in 2011 analyzed the DNA of over 27,000 people and revealed, in addition to the APOE gene, four more genes associated with Alzheimer’s: MS4A4/MS4A6E, CD2AP, CD33, and EPHA1.⁵ These genes are linked to critical brain functions such as immune response, cellular communication, and the brain’s ability to clear waste — which can impact disease development.⁶
Genetic risk does not exist in isolation. Environmental and lifestyle factors — often referred to as epigenetics — can influence how our genes behave. Elements such as diet, physical activity, sleep, and exposure to toxins like tobacco smoke may either increase or reduce the risk of Alzheimer’s, even for those with genetic predispositions.⁴
Because of this complexity, genetic testing for Alzheimer’s is not currently recommended for most people. The presence of risk variants cannot predict with certainty who will develop the disease, and the data is continually evolving as research advances. At this time, testing may cause more confusion or anxiety than clarity for the general public.⁴
What we do know is that aging remains the biggest risk factor. Many people with genetic variants never develop the disease, and some without any known risk genes still do. This reinforces the idea that Alzheimer’s results from the interaction of many small factors, both genetic and environmental, over time.
Ultimately, understanding genetic risk helps researchers build better models of susceptibility — not to provide certainty, but to guide prevention and early intervention strategies. While science continues to uncover how genes and lifestyle intersect in Alzheimer’s, maintaining a healthy life as we age remains one of the most reliable ways to reduce risk.
References:
1) https://www.nhs.uk/conditions/alzheimers-disease/causes/
2) https://www.uchealth.org/today/alzheimers-disease-and-genetics-a-complicated-relationship/
3) https://www.health.harvard.edu/mind-and-mood/alzheimers-in-the-family
