Q: How long does Alzheimer's disease last on average?

A: The sporadic form of Alzheimer's disease on average, given the state of good supportive care, can last from 5 to 20 years. The average, calculated by the Alzheimer's Association, is around 8 to 12 years. There are progressions, or stages, of the disease.

In general, there is a phase in which learning and memory performance is mildly compromised. This stage can last as short as few months or as long as a few years. This phase transitions into the next, consisting of severe fading of learning and memory capability that develops over the course of a few years.

Finally, the patient with a fully developed clinical picture of the disease falls into a final state in which the sense of self is lost. The familiar, although rare, early onset form of the disease rapidly progresses and rarely the patient survives eight years from the diagnosis.