Scientists do not yet fully understand what causes Alzheimer's disease. For most people there probably is not one single cause, but several genetic, environmental, and lifestyle factors that affect each person differently. Increasing 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 is another risk factor for Alzheimer's disease. Early-onset familial Alzheimer's disease, a rare form of Alzheimer's that occurs between the ages of 30 and 60, is inherited. It is caused by mutations, or changes, in certain genes.
The more common form of Alzheimer's disease is known as late-onset. It occurs after age 60. No obvious family pattern is seen in most of these cases. But genetic factors appear to increase a person's risk of developing late-onset Alzheimer's.
The increased genetic risk of late-onset Alzheimer's is related in some way to a gene called apolipoprotein E, or APOE. One form of the APOE gene occurs in about 40 percent of all people who develop late-onset Alzheimer's. But many people who get Alzheimer's do not have this form of the gene, and some people with this form of the gene never get Alzheimer's.
Scientists still need to learn a lot more about causes and risk factors. In addition to genetics and studies of pathways in the brain affected by the disease, they are also studying lifestyle factors, such as diet, exercise, and social engagement. Scientists are finding more clues that some health conditions, like heart disease, high blood pressure, diabetes, and obesity, are related to Alzheimer's disease. It's possible that controlling these conditions will reduce the risk of getting Alzheimer's.
Research suggests that these steps might lower the risk of developing Alzheimer's disease:
- lowering high blood pressure and high cholesterol levels
- controlling diabetes
- being physically active
- eating a healthy diet
- engaging in activities that stimulate the mind
More studies are being done to see which health and lifestyle factors directly affect the chances of developing Alzheimer's. Many of these factors are known to lower the risk for other diseases and help maintain and improve overall well-being, so they are good to do anyway. Currently, there are no treatments, drugs, or pills that can prevent Alzheimer's disease.