We would all like to prevent Alzheimer’s disease, postpone its onset, slow its clinical course. Many people in medicine and science are thinking about how to do this now, but we do not yet know enough to be sure that we can do it. Often, in the history of medicine, before diseases can be prevented, they must first go through a phase in which treatments are developed. It may be that this is how it will go with Alzheimer’s disease. Medical and non-medical treatments presently exist for Alzheimer’s disease and related disorders, and many new ones are under development.

Current thinking about prevention in Alzheimer’s disease takes the form of attempting to modify “risk factors” for the disease. Risk factors for a disease can be several things. Some, like onset of early memory loss in later life, can be iceberg tips of the disease to come. Others, like elevated cholesterol in middle age, can be causative variables, which act slowly over time to drive the pathology of the disease. Others may represent passenger or bystander variables, such as coffee drinking amongst cigarette smokers. And then, unfortunately, many risk factors in large population studies turn out to be artifacts of selection bias that enter into all scientific studies.

In Alzheimer’s disease we know that causative risk factors exist, and we are certain some of them are modifiable.
But we are not really sure yet what all the risk factors are.

• We do know that aging and genetics are powerful, causative risk factors for Alzheimer’s disease.
• The inheritance of an apolipoprotein E4 allele is associated with a greater risk of developing AD, and perhaps a faster course of decline once the disease starts.
• Having a positive family history for AD also increases risk.

And of course, the greatest risk factor of all for Alzheimer’s disease is surviving into the eighth decade of life — but this is one few wish to modify.