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Causes & Risk Factors

Woman head. Half of the face looks young and the other looks old. It shows the aging process.


The greatest known risk factor for Alzheimer's is increasing age. One out of eight people over age 65 has Alzheimer's. Nearly half of people over age 85 have the disease.

DNA chain


Another risk factor is family history. Research has shown that those who have a parent, brother or sister with Alzheimer's are two to three times more likely to develop the disease. The risk increases if more than one family member has the illness.

Scientists have identified one gene that increases the risk for Alzheimer's but does not guarantee an individual will develop the disease. Research has also revealed certain rare genes that virtually guarantee an individual will develop Alzheimer's. These genes have been found in only a few hundred extended families worldwide and account for probably fewer than 1 percent of all cases of Alzheimer's.

Black young woman cooking healthy food.


Age, family history and heredity are all risk factors we can't change. Now, research is beginning to reveal clues about other risk factors we may be able to influence.

There appears to be a strong link between serious head injury and future risk of Alzheimer's. It's important to protect your head by buckling your seat belt, wearing your helmet when participating in sports and "fall-proofing" your home.

Some evidence suggests that strategies for general healthy aging may also help reduce the risk of developing Alzheimer's. These measures include controlling blood pressure, weight and cholesterol levels; exercising both body and mind; eating a balanced diet; and staying socially active.

Latinos and African Americans are at particularly high risk for Type 2 diabetes, which may be linked to Alzheimer's disease.

finger being pricked to test blood sugar


Scientists don't know yet exactly how Alzheimer's and diabetes are connected, but they do know that excess blood sugar or insulin can harm the brain in several ways:

  • Diabetes raises the risk of heart disease and stroke, which hurt the heart and blood vessels. Damaged blood vessels in the brain may contribute to Alzheimer's disease.

  • The brain depends on many different chemicals, which may be unbalanced by too much insulin. Some of these changes may help trigger Alzheimer's disease.

  • High blood sugar causes inflammation. This may damage brain cells and help Alzheimer's develop.

Work with your doctor to detect the first signs of diabetes or other health concerns. Even if you develop diabetes, treating it may help prevent other complications, such as Alzheimer's disease.

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