Complications (1)
- Alzheimer's: Managing sleep problems
Definition (1)
- Early-onset Alzheimer's: When symptoms begin before 65
Risk factors (2)
- Diabetes and Alzheimer's linked
- Alzheimer's: Is it in your genes?
Symptoms (3)
- Memory loss: When to seek help
- Alzheimer's stages: How the disease progresses
- Alzheimer's or depression: Could it be both?
Tests and diagnosis (3)
- Diagnosing Alzheimer's: An interview with a Mayo Clinic specialist
- Positron emission tomography (PET) scan
- SPECT scan
Treatments and drugs (3)
- Alzheimer's: Getting the most from medical appointments
- Alzheimer's treatments: What's on the horizon?
- Alzheimer's drugs slow progression of disease
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Alzheimer's: Is it in your genes?
What role does genetics play in developing Alzheimer's? Are you at risk?
By Mayo Clinic staffGenes control the function of every cell in your body. Some genes determine basic characteristics, such as the color of your eyes and hair. Other genes can make you more likely to develop certain diseases — including Alzheimer's.
Researchers have identified several genes that are associated with Alzheimer's disease. But genetic risk factors are just one part of the Alzheimer's story. According to the National Institutes of Health, 75 percent of the people who get Alzheimer's disease have no family history of the disorder.
Most common Alzheimer's gene
While some rare forms of Alzheimer's occur before the age of 65, the most common variety of Alzheimer's usually begins after the age of 65. The most common gene associated with this late-onset Alzheimer's is called apolipoprotein E (APOE).
APOE has three common forms:
- APOE e2 is the least common. It appears to reduce the risk of Alzheimer's.
- APOE e4 is a little more common. It appears to increase the risk of Alzheimer's.
- APOE e3 is the most common. It doesn't seem to affect the risk of Alzheimer's in either direction.
Genes aren't only factor
Because you inherit one APOE gene from your mother and another from your father, you may have two different types of APOE genes — for example, one APOE e3 gene and one APOE e4 gene. Having at least one APOE e4 gene increases your risk of developing Alzheimer's. And if you have two APOE e4 genes, your risk is even higher.
But not everyone who has an APOE e4 gene — or even two APOE e4 genes — develops Alzheimer's. And the disease occurs in many people who have no APOE e4 gene. This indicates other factors are involved in the development of Alzheimer's.
Another late-onset gene
Study results also show a link between late-onset Alzheimer's and a gene known as SORL1. This is the first gene, other than APOE, to be linked to the most common form of Alzheimer's. Some variations of SORL1 appear to increase the production of amyloid-beta fragments, which form structures called amyloid plaques in the brain. These plaques are one of the hallmarks of Alzheimer's disease.
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