Alzheimer's disease is a progressive brain disorder that destroys memory and thinking skills. It is the most common cause of dementia among older adults. The main risk factor is increasing age, and symptoms usually appear after age 65. Alzheimer's damages and kills brain cells, leading to the shrinkage of the brain. This causes problems with memory, thinking, and behavior severe enough to affect work and daily living. The three main changes in the brain of those with Alzheimer's are loss of connections between neurons, the buildup of amyloid plaques, and tangles within neurons made of the tau protein. There is no cure for Alzheimer's, and treatment seeks to temporarily slow the worsening of symptoms.