There is an interesting article about Alzheimer's in the New York Times online (December 26, 2007).
Alzheimer's has such a high rate of dementia, disability and mortality because we are now just treating the symptoms of the disease once it has progressed, and are not able to find this disease in its earlier stages.
Researchers are studying the treatment, early detection and ultimate prevention of Alzheimer's, and are focusing on an abnormal protein called beta amyloid (A-beta) that is over-deposited, causing plaques, in the brain. If amyloid causes Alzheimers, it is possible that early detection of this protein (using brain scans), coupled with early treatment, can help prevent this disease. Several drugs and vaccines are being tested, in hopes that they rid the body of A-beta or block its production.