Alzheimer’s disease accounts for as much as 70 percent of dementia, a general term for the impairment or loss of mental abilities including memory and reasoning skills. Dementia used to be considered a normal part of aging, but now it is understood in terms of an injury or disease process that damages brain cells and disrupts the person’s normal way of thinking, feeling and behaving. Different types of dementia are linked to types of cell damage in particular parts of the brain.
The specific cause of Alzheimer’s is not yet known, but researchers have identified two abnormal structures—called plaques and tangles—believed to play a role in the brain cell damage found in Alzheimer’s. Plaques are deposits of a protein called beta-amyloid that builds up in spaces between brain cells. Tangles are twisted fibers of a protein called tau that builds up inside the cells. Most people develop some plaques and tangles but excessive amounts are found in the brains of Alzheimer’s patients, especially in parts of the brain involved in memory.
Alzheimer’s symptoms appear gradually and get worse over time. Symptoms usually start with difficulty remembering new information. In advanced stages, symptoms include disorientation, mood and behavior changes, and growing confusion about events, time and place. In advanced Alzheimer’s, the person is unable to perform basic life tasks and care can place great demands on families and caregivers.
Organizations like the Alzheimer’s Association offer information and support.
The greatest known risk for Alzheimer’s is increasing age. Although more women are diagnosed than men, this is believed to reflect women’s longer life expectancy. There is evidence that certain genetic characteristics increase likelihood of developing Alzheimer’s, but only in a very few cases (about 1%) has Alzheimer’s been found to run in families.
There is no cure for Alzheimer’s, but recent advances in research have provided treatments that can temporarily slow the worsening of symptoms and improve quality of life.