What is the life expectancy of a person with Alzheimer's?

There's no simple answer. The general rule of thumb is that a person diagnosed with Alzheimer's can expect to live half as along as a peer who doesn't have the disease. For example, the average 75-year-old in 2007 can expect to live another 12 years. A 75-year-old with Alzheimer's, in contrast, would be expected to live for six more years.

It's hard to gauge an individual's life expectancy based solely on the stage of Alzheimer's. That's partly because the length of each stage(early/middle/late) can vary greatly from individual to individual. Some people live 15 or more years after diagnosis, including many years with relatively mild impairment, while others decline rapidly and die within a few years of being diagnosed. In general, someone who's just beginning to show symptoms can be expected to live longer than someone of the same age with end-stage Alzheimer's.

Here's more on what influences lifespan with Alzheimer's.