Causes of Alzheimer's Disease
While scientists know Alzheimer's disease involves progressive brain cell failure, the reason cells fail isn't clear. Like other chronic conditions, experts believe that Alzheimer's develops as a complex result of multiple factors rather than any one overriding cause. Both age and genetics have been identified as risk factors, but many questions still remain. The discovery of additional risk factors will deepen our understanding of why Alzheimer's develops in some people and not others.

Family history and Alzheimer's
Another Alzheimer's risk factor is family history. Research has shown that those who have a parent, brother, sister or child with Alzheimer's are more likely to develop the disease. The risk increases if more than one family member has the illness. When diseases tend to run in families, either heredity (genetics) or environmental factors or both may play a role.

Genetics and Alzheimer's
There are two categories of genes that influence whether a person develops a disease: (1) risk genes and (2) deterministic genes. Researchers have identified Alzheimer's genes in both categories.

Age and Alzheimer's
Although Alzheimer's is not a normal part of growing older, the greatest risk factor for the disease is increasing age. After age 65, the risk of Alzheimer's doubles every five years. After age 85, the risk reaches nearly 50 percent.