There is much that is unknown about Alzheimer's disease, including the cause or causes and how to slow or stop its progress. Because of this, Alzheimer's disease is a difficult disease to prevent.

There is some evidence that indicates that people who sustain severe head injuries are more likely to develop Alzheimer's disease later in life. For this reason, it is important to always wear a seatbelt while traveling in a car and to wear protective headgear while operating a motorcycle or bicycle, or while playing contact sports.

Other studies have shown that oxidative stress, the process of cell damage by free radicals, contributes to the risk of developing Alzheimer's disease. Oxidative stress can be prevented by consuming foods that are high in antioxidants, such as olive oil, fish and fresh fruit and vegetables. It can also be prevented by taking supplements of vitamin A, C and E, although a physician should always be consulted before starting any supplements.

It is also becoming clear that maintaining brain health by remaining physically and mentally active throughout life, especially in later life, is important. This includes controlling weight, blood pressure and cholesterol levels. It is not known whether physical and mental activity directly reduce the risk of developing Alzheimer's disease, but scientists agree that it appears reasonable that keeping the body and mind healthy is beneficial on many levels.