About Alzheimer's Disease: Causes
how the brain changes normally with age is shedding light on this question. For example, scientists are learning how age-related changes in the brain may harm neurons and contribute to Alzheimer’s damage.
Early-onset Alzheimer’s is a rare form of the disease. It occurs in people age 30 to 60 and represents less than 5 percent of all people who have Alzheimer’s disease. Most cases of early-onset Alzheimer’s are familial Alzheimer’s disease, caused by changes in one of three known genes inherited from a parent.
Most people with Alzheimer’s disease have “late-onset” Alzheimer’s, which usually develops after age 60. Many studies have linked the apolipoprotein E (APOE) gene to late-onset Alzheimer’s. This gene has several forms. One of them, APOE ε4, seems to increase a person’s risk of getting the disease. However, carrying the APOE ε4 form of the gene does not necessarily mean that a person will develop Alzheimer’s disease, and people carrying no APOE ε4 can also develop the disease.
Most experts believe that additional genes may influence the development of late-onset Alzheimer’s. Scientists around the world are searching for these genes, and have identified a number of common genes in addition to APOE ε4 that may increase a person’s risk for late-onset Alzheimer’s.
For more about this area of research, see the Alzheimer’s Disease Genetics Fact Sheet.
"Looking for the Causes of AD"
NIA Information on Causes
- What You Need to Know This 19-page booklet describes what happens when someone has Alzheimer’s disease and how it differs from normal aging. Read about when to see the doctor, possible treatments, and how patients and caregivers can get help...
- Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills, and eventually even the ability to carry out the simplest tasks. In most people with Alzheimer’s, symptoms first appear...
- Scientists don't yet fully understand what causes Alzheimer's disease. However, the more they learn about this devastating disease, the more they realize that genes* play an important role in its development. Research conducted and funded by...
- An essential primer on Alzheimer’s disease, this 80-page publication describes how the brain works and how it changes with age in healthy people and people with Alzheimer’s. Research on causes, diagnosis, prevention, potential treatments...
- New grants boost Alzheimer's research
June 1, 2010