Genes that cause young-onset Alzheimer's

Less often, young-onset Alzheimer's is caused by changes in a gene, called a genetic mutation. Genetic changes can be passed from parent to child. If a genetic mutation directly causes a disease, it is called a causal gene. Having a causal gene means you are likely to develop the disease.

Three different genes may have a mutation that causes young-onset Alzheimer's disease. These genes are APP, PSEN1 or PSEN2. A person who gets at least one copy of a mutated gene is likely to develop Alzheimer's disease before age 65.

About 10% or less of people with young-onset Alzheimer's carry a genetic mutation that causes the disease. Among all people with Alzheimer's disease, fewer than 1% carry one of these causal genes.

Genetic testing for these gene changes is available. If you have a family history of young-onset Alzheimer's, you may want to take that step. The longer a mutation has appeared in a person's family history, the higher the chance is that genetic tests will find the specific gene causing the disease. But genetic counseling is recommended before you get tested to learn the pros and cons of genetic testing.

For example, if you know that you carry a young-onset gene, you may be able to take steps that make it easier for you and family members to cope with the effects of the disease. On the other hand, finding out you have a gene for young-onset Alzheimer's may affect your ability to get long-term care, disability and life insurance.

You might be able to take part in a research study if you have young-onset Alzheimer's linked to one of the three genes. Or if you carry a form of these genes but have no symptoms. Talk with your healthcare professional to find out more. By studying the young-onset form of Alzheimer's, researchers hope to learn more about the causes of the disease and how it changes over time. This research also may lead to new treatments.