Alzheimer's disease is a brain disorder that causes memory loss and cognitive decline. It is the most common cause of dementia. The main risk factors are age, family history, and genetics. Alzheimer's is caused by plaques and tangles accumulating in the brain, which disrupt communication between neurons. This leads to problems with memory, thinking, language, behavior, and the ability to perform everyday tasks. Symptoms gradually worsen over time as more brain cells are lost. While there is no cure, medications can temporarily slow the worsening of symptoms for some people.