Alzheimer's disease is a progressive brain disorder that causes memory loss and cognitive decline. It is the most common form of dementia and develops due to a complex biological process in the brain over many years. Approximately 5.3 million Americans have Alzheimer's currently, and it is the fifth leading cause of death among those aged 65 and older. Symptoms include memory loss, problems with language, disorientation, and changes in mood and personality. Alzheimer's progresses through mild, moderate and severe stages as cognitive abilities and independence decline. While there is no cure, certain drugs can temporarily slow the worsening of symptoms for some individuals.