Less commonly, young-onset Alzheimer's is caused by a specific error in a gene, called a genetic mutation. Genetic mutations can be passed from parent to child.
Three different genes may have a mutation that causes young-onset Alzheimer's disease. These genes are APP, PSEN1 or PSEN2. A person who inherits at least one copy of a mutated gene will likely develop Alzheimer's disease before age 65.
About 11% of people with young-onset Alzheimer's carry a genetic mutation that causes disease. But among all people with Alzheimer's disease, fewer than 1% carry one of these causal genes.
Genetic testing for these mutations is available. If you have a family history of young-onset Alzheimer's, you may want to do genetic testing. But genetic counseling is recommended for learning about the pros and cons of being tested before taking that step.
For example, if you know that you carry a young-onset gene, you may be able to take steps to make it easier for you and family members to cope with the effects of the disease. On the other hand, identifying a gene for young-onset Alzheimer's may affect your ability to get long-term care, disability and life insurance.
If you have young-onset Alzheimer's linked to one of the three genes or if you carry a form of these genes without symptoms, talk to your healthcare professional about participating in a research study. By studying the young-onset form of Alzheimer's, researchers hope to learn more about the causes and progression of the disease. This research also may lead to new treatments.