Helios Health Team
Alzheimer's disease (AD) is one of the most common causes of the loss of mental function known broadly as dementia. This type of dementia proceeds in stages, gradually destroying memory, reason, judgment, language, and eventually the ability to carry out even the simplest of tasks.
These characteristic symptoms acquired a name in the early part of the 20th century when Alois Alzheimer, a German physician, described the signs of the disease in the brain. Alzheimer had a patient in her fifties who suffered from what seemed to be a mental illness. But when she died in 1906, an autopsy revealed dense deposits, now called neuritic plaques, outside and around the nerve cells in her brain. Inside the cells were twisted strands of fiber, or neurofibrillary tangles. Today, a definite diagnosis of Alzheimer's disease is still only possible when an autopsy reveals these hallmarks of the disease.
Plaques and tangles remained mysterious substances until the 1980's, when neuroscientists--the scientists who study the brain--discovered the proteins that make up these telltale anomalies. As research progresses, it is turning up clues to how plaques and tangles develop and how they relate to other changes in the brain.
In the meantime, much more about the disease has come to light. We now know that Alzheimer's begins in the entorhinal cortex and proceeds to the hippocampus, a waystation important in memory formation. It then gradually spreads to other regions, particularly the cerebral cortex. This is the outer area of the brain, which is involved in functions such as language and reason. In the regions attacked by Alzheimer's, the nerve cells or neurons degenerate, losing their connections or synapses with other neurons. Some neurons die.
Every day, scientists learn more about AD, but right now the cause of the disease still is unknown, and there is no cure. An estimated 4 million people in the United States suffer from AD. The disease usually begins after age 65, and risk of AD goes up with age. While younger people also may have AD, it is much less common. About 3 percent of men and women ages 65 to 74 have AD, and nearly half of those age 85 and older may have the disease. It is important to note, however, that AD is not a normal part of aging.