Young-onset Alzheimer's

A very small number of people who get Alzheimer's disease have the young-onset type. Symptoms of this type of Alzheimer's usually appear between ages 30 and 60. Young-onset Alzheimer's disease, also called early-onset Alzheimer's, has a strong genetic link.

Scientists have found three genes in which changes cause young-onset Alzheimer's disease. The genes are:

• Amyloid precursor protein, also called APP.
• Presenilin 1, also called PSEN1.
• Presenilin 2, also called PSEN2.

Variants of these genes can lead to changes in the brain that are common in people with Alzheimer's disease. A person who inherits one of these deterministic variants from either parent is likely to get Alzheimer's symptoms before age 65.

Alzheimer’s-related changes in the brain include the formation of hardened clumps of beta-amyloid protein, called amyloid plaques, and snarled tangles of a protein called tau.

A buildup of amyloid plaques and tau tangles can lead to the death of nerve cells and the symptoms of Alzheimer's disease.

Still, some people who have young-onset Alzheimer's don't have changes in any of these three genes. That suggests some young-onset types of Alzheimer's disease are linked to other gene changes or other things that have yet to be found.