Alzheimer's disease is the most common form of dementia.

It affects around 5.7 million people in the United States — and this number is predicted to rise.

Some estimate that, by 2050, 13.8 million U.S. adults might be affected.

Despite its growing prevalence, treatment options are lacking and there is no cure.

The exact causes are not yet known, so a great deal of research goes into understanding what factors increase the risk of developing Alzheimer's. By recognizing the risk factors, it may be possible to significantly reduce the chances of getting Alzheimer's.

To date, a number of these risk factors have been discovered. The most well-known is age; most people who develop Alzheimer's are 65 or older. After the age of 85, the risk of developing Alzheimer's is almost one third.

Genetic factors also play a role; a person's risk increases if a family member has had the disease, and certain genes have been identified that are strongly linked to Alzheimer's risk.

Diet may also play a role, as might mental and physical activity. According to the latest research, sleep might soon be added to the list, too.