Causes of Alzheimer's Disease: An Overview
Scientists do not yet fully understand what causes
Alzheimer's disease. However, they do believe that there is more than one single cause of
Alzheimer's disease and that different factors affect each person differently.
Causes of Alzheimer's Disease and Risk Factors
While there are no known causes of Alzheimer's disease, there are factors that can increase your risk for developing Alzheimer's disease. These are known as Alzheimer's disease risk factors.
Alzheimer's disease risk factors include:
- Age
- Family history
- Certain genes.
Age
Age is the most important known risk factor for Alzheimer's disease. The number of people with the disease doubles every 5 years beyond age 65.
Family History
Family history is another risk factor. Scientists believe that genetics may play a role in many cases of Alzheimer's disease. For example, familial Alzheimer's disease (a rare form of Alzheimer's disease that usually occurs between the ages of 30 and 60) is inherited.
Certain Genes
The more common form of Alzheimer's disease is known as late-onset Alzheimer's. It occurs later in life, and no obvious inheritance pattern is seen in most families. However, several risk factor genes may interact with each other and with non-genetic factors to cause the disease.
The only risk factor gene identified so far for late-onset Alzheimer's disease is a gene that makes one form of a protein called apolipoprotein E (ApoE). Everyone has ApoE, which helps carry cholesterol in the blood. Only about 15% of people have the form that increases the risk of Alzheimer's disease. It is likely that other genes may also increase the risk of Alzheimer's disease or protect against Alzheimer's disease, but they remain to be discovered.
