Alzheimer's disease is named after Dr. Alois Alzheimer, a German doctor. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. He found abnormal clumps and tangled bundles of fibers. The clumps are now called amyloid plaques and the tangles are called neurofibrillary tangles. Today, these plaques and tangles in the brain are considered hallmarks of Alzheimer's disease.

Scientists also have found other brain changes in people with Alzheimer's disease. There is a loss of nerve cells in areas of the brain that are vital to memory and other mental abilities. There also are lower levels of chemicals in the brain that carry complex messages back and forth between nerve cells.

Alzheimer's disease may disrupt normal thinking and memory by blocking these messages between nerve cells.

1. Alzheimer's disease is the most common form of dementia among older people.

TRUE is the correct answer. Although there are other forms of dementia associated with aging, Alzheimer's disease is the most common form.

2. Alzheimer's disease is a normal part of aging.

FALSE is the correct answer. Although Alzheimer's disease usually begins after 60 and is more common among older people, it is not a normal part of aging.

3. When researchers examine the brains of people who have died of Alzheimer's, they find nothing unusual.

FALSE is the correct answer. The brain tissue of people who have died from Alzheimer's disease contains abnormal clumps called amyloid plaques and bundles of fibers called neurofibrillary tangles. These plaques and tangles are considered the hallmarks of Alzheimer's disease.

4. Scientists believe that about 40 million people in the United States suffer from Alzheimer's.

FALSE is the correct answer. It is estimated that approximately 4 million people in the United States suffer from Alzheimer's disease.