Alzheimer's disease is the most common type of dementia. It is a degenerative disease of the brain, and it will gradually lose memory, judgment, and operation. Diseases can be classified as early onset or late onset.

Early-onset symptoms appear before age 65, while late-onset symptoms occur after age 65.

Memory loss is the key symptom of Alzheimer's disease. The longer the time, the more memory loss will worsen and eventually affect daily life activities (getting lost, confused, unable to distinguish other people's things.). As the disease progresses, personality and behavior will gradually change, making joining social activities and everyday interactions challenging. People with this disease usually require total care in the later stages. Affected people typically survive 8 to 10 years after symptoms appear, but the illness lasts 25 years.