Understanding Alzheimer's Disease -- the Basics
What Causes Alzheimer's Disease? continued...
As with all proteins, the form of ApoE that people have in their bodies is genetically determined, and several different types have been identified -- some of them apparently associated with a higher risk of Alzheimer's. It may be that certain forms of ApoE lead to the brain damage.
Another possibility is that the protein, perhaps working in combination with other substances, is involved in the formation of the plaques. Whether or not ApoE partly causes Alzheimer's disease, genes almost certainly play a role in the disease, and a person with a parent who had Alzheimer's disease is at higher risk.
There is some evidence that people with high blood pressure and high cholesterol have an increased chance of developing Alzheimer's. In a minority of cases, head trauma may be a contributing factor (the more severe the head injury, the greater the risk of Alzheimer's dementia later in life).
While many of these theories are still being studied, it is clear that the biggest risk factors associated with developing Alzheimer's disease are increasing age and family history.