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. 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.