Alzheimer's Myth 5

Myth 5: "My parent has Alzheimer's, so I'll probably get it too."

Having a parent or sibling with Alzheimer's does increase your risk for developing the disease compared to someone without a familial link. But it doesn't mean you're likely to get it. Family history only increases your risk slightly.

The role of genetics in the development of Alzheimer's disease is still under investigation. Researchers have identified a "risk gene" called APOE-e4 (apoliprotein E-e4). APOE-e4 is one of three common forms of the APOE-e gene. Everybody inherits some form of that gene. Inheriting APOE-e4 from one or both parents is known to raise the risk of developing Alzheimer's. But how this works is unknown, and it's likely other genes are also involved.

Specific forms of Alzheimer's disease are more likely to run in families: for example, familial Alzheimer's disease, an early-onset type that accounts for fewer than 10 percent of people with Alzheimer's. It's caused by one of several rare gene mutations. More common forms of the disease, those with a "late onset," however, don't demonstrate a clear pattern of heredity.

Genetic tests are available that can identify the form of the APOE gene a person has, as well as the known rare gene mutations. A special lab must run these blood tests; a genetic counselor can assess the risks and benefits of testing for the possibility of a disease for which there is no cure. Most doctors don't recommend routine testing. But you should decide what's right for the person you're caring for and her family.