Alzheimer's is a neurological disease that was first discovered by Dr. Alois Alzheimer's in 1906. Alzheimer's disease is a progressive, degenerative neurological disease of the brain. It is not the most common, but not the only form of Dementia, accounting for about 70% of the diagnosed cases.

It has seven stages, and can last from 2 to 20 years from the time of diagnosis. The average is eight.

A person can pass smoothly from stage to stage, go backwards or even "plateau," that in one stage for a disproportionate amount of time. It is a terminal disease, so regardless of irregularities in the journey; on the whole the graph will be on the decline.

It is a disease of the nervous system and the part of the nervous system that is affects the brain. Specifically, the pathological damage occurs in certain parts of the brain -- the hippocampus and frontal lobes, where the characteristic amyloid plaques (hallmarks of the disease seen upon autopsy) are observed to concentrate.