Scientists do not yet fully understand what causes Alzheimer's disease. There probably is not one single cause, but several factors that affect each person differently. 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. Scientists believe that genetics may play a role in the causes of Alzheimer's disease. For example, early-onset familial Alzheimer's disease, a rare form of Alzheimer's disease that occurs between the ages of 30 and 60, is inherited.
The more common form of Alzheimer's disease is known as late-onset. It occurs later in life, and no obvious family pattern is seen in most cases. One risk factor for this type of Alzheimer's disease is a gene that makes one form of a protein called apolipoprotein E, or apoE.
Everyone has apoE, which helps carry cholesterol in the blood. Only about 15 percent of people have the form that increases the risk of Alzheimer's. It is likely that other genes may also increase the risk of Alzheimer's or protect against it, but they remain to be discovered.
Scientists still need to learn a lot more about causes and risk factors. In addition to genetics and apoE, they are studying education, diet, environment, and molecular changes in the brain to learn what role they might play in the development of this disease.
Scientists are finding more clues that some of the risk factors for heart disease and stroke -- like high blood pressure, high cholesterol, and low levels of the vitamin folate -- may also increase the risk of Alzheimer's. Researchers are also investigating the possibility that physical, mental, and social activities may protect against Alzheimer's.
Studies have shown that keeping the brain active may be associated with a reduced risk of Alzheimer's. In a study with nuns, priests, and brothers known as the Religious Orders study, researchers asked more than 700 participants to describe the amount of time they spent in mentally stimulating activities.
These activities included listening to the radio, reading newspapers, playing puzzle games, and going to museums. After following the participants for four years, researchers found that the risk of developing Alzheimer's was 47 percent lower on average for those who did these mentally stimulating activities most frequently than for those who did them least frequently.
There are no treatments, drugs, or pills that can prevent Alzheimer's, but people can take some steps that may reduce their risk. These include:
- lowering cholesterol and homocysteine levels
- lowering high blood pressure levels
- controlling diabetes
- exercising regularly
- engaging in activities that stimulate the mind
- A healthy diet is important. Although no special diets or nutritional supplements have been found to prevent or reverse Alzheimer's disease, a balanced diet helps maintain overall good health.
Research has not shown that these steps will lower your risk for Alzheimer's, and studies designed to directly test their ability to do so are currently in progress. However, all of these things are good to do anyway because they lower the risk for other diseases and help maintain and improve your overall health and well-being.