Diseases that run in families usually have genetic causes. Some are genetic mutations that directly cause the disease if inherited. Others are risk genes that affect the body in a way that increases the chance someone will develop the disease. In Alzheimer’s disease, genetic mutations in any of three specific genes can cause the disease, and other risk genes either increase or decrease the risk of developing Alzheimer’s.
Some genetic mutations or variants interact with other genetic alterations that lead to Alzheimer’s disease. In some cases, gene alterations can interact with Alzheimer’s-causing genetic variants in a way that proves beneficial; they actually suppress the pathological brain changes the other mutations would normally lead to. These protective gene variants can drastically slow or prevent cognitive decline. In two recent case reports on familial Alzheimer’s disease, mutations delayed Alzheimer’s symptoms for decades.
