The disease is named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems, and unpredictable behavior. After she died, he examined her brain and found many abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles). Plaques and tangles in the brain are two of the main features of Alzheimer’s disease. The third is the loss of connections between nerve cells (neurons) in the brain. Alzheimer’s disease. In people age 65 and older, Alzheimer’s disease is the most common cause of dementia. People generally may develop symptoms after age 60, but some people may have early-onset forms of the disease, often as the result of a defective gene. Although in most cases the exact cause of Alzheimer’s disease isn’t known, plaques and tangles are often found in the brains of people with Alzheimer’s.
Plaques are clumps of a protein called beta-amyloid, and tangles are fibrous tangles made up of tau protein. Certain genetic factors also may make it more likely that people will develop Alzheimer’s. Alzheimer’s disease usually progresses slowly over seven to 10 years. Your cognitive abilities slowly decline. Eventually, the affected areas of your brain don’t work properly, including parts of your brain that control memory, language, judgment and spatial abilities. Alzheimer’s disease is an irreversible, progressive brain disease that slowly destroys memory and thinking skills and, eventually even the ability to carry out the simplest tasks of daily living. In most people with Alzheimer’s, symptoms first appear after age 60. Alzheimer’s disease is the most common cause of dementia among older people.
Although treatment can help manage symptoms in some people, currently there is no cure for this devastating disease. Although we still don’t know how the Alzheimer’s disease process begins, it seems likely that damage to the brain starts a decade or more before problems become evident. During the preclinical stage of Alzheimer’s disease, people are free of symptoms, but toxic changes are taking place in the brain. Abnormal deposits of proteins form amyloid plaques and tau tangles throughout the brain, and once-healthy
neurons begin to work less efficiently. Over time, neurons lose the ability to function and communicate with each other, and eventually they die. Before long, the damage spreads to a nearby structure in the brain called the hippocampus, which is essential in forming memories. As more neurons die, affected brain regions begin to shrink. By the final stage of Alzheimer’s, damage is widespread, and brain tissue has shrunk significantly. Alzheimer’s is a slow disease that progresses in three stages—an early, preclinical stage with no symptoms, a middle stage of mild cognitive impairment, and a final stage of Alzheimer’s dementia. The time from diagnosis to death varies—as little as 3 or 4 years if the person is older than 80 when diagnosed to as long
as 10 or more years if the person is younger.