What is Alzheimer's disease?

Alzheimer's disease is the most common cause of dementia, a progressive brain disease that usually begins with difficulty remembering recent events. It is linked to two abnormal proteins, amyloid plaques and tau tangles, that start building up years before symptoms appear. It accounts for roughly 60 to 80 percent of dementia cases and typically progresses over several years.

Early onset Alzheimer's, also called younger onset, is Alzheimer's disease that begins before age 65. It is much less common than the usual form, since most people with Alzheimer's are 65 or older. Some cases are linked to rare inherited genes. Because people are often still working and raising families, a diagnosis brings particular planning needs, and a doctor should assess early symptoms.

Scientists do not yet fully understand what causes Alzheimer's disease in most people. Its hallmark is a buildup of amyloid plaques and tau tangles that damage brain cells. The Alzheimer's Association says the greatest known risk factor is increasing age, with risk doubling every five years after 65, and family history and genetics also play a part.

Usually not in a direct way. The Alzheimer's Association explains that rare deterministic genes directly cause the disease in a small number of families, while risk genes such as APOE e4 raise the likelihood without guaranteeing it. Researchers estimate that 40 to 65 percent of people diagnosed with Alzheimer's carry APOE e4, but many carriers never develop the disease.

No. There is currently no cure for Alzheimer's disease. The Alzheimer's Association notes that current medications cannot cure it, though some help with memory and behavior symptoms, and lecanemab and donanemab are FDA approved for early Alzheimer's because they target its underlying biology. Care, routine and support also make a real difference. A doctor can explain which treatments may fit.