Signs of cognitive issues that appear before the age of 65 indicate early onset Alzheimers disease. Early onset is considered to be rare, and genetics appears to be a factor.
Researchers do not yet know what triggers the development of early onset. It is known that approximately 5% of those with Alzheimer’s disease develop the non-familial form of early onset. Those with non-familial early onset can develop the disease in their 30’s, 40’s, or 50’s but it is extremely rare.
Familial early onset is a different form that appears to be linked with having a parent or grandparent who also developed the disease at a young age.