Though the study still has a ways to go before everyone starts chugging java 'round the clock (and we really mean it since you'll be up for days drinking so much caffeine!), it does appear that caffeine and a mystery ingredient in coffee prevented mice bred to develop Alzheimer's from displaying signs of the disease. It might also help with other health issues.
From an article in a Florida newspaper:
"We found that caffeinated coffee has some rather astounding additions to caffeine that provide protection" against cognitive impairment, said Arendash. The result, he said, was a sharper increase in blood levels of growth factor called GCSF. This protein — granulocyte colony stimulating factor — is known to bolster the human immune system and has shown promise in animal studies for repairing damage from a stroke.Scientists don't know what other chemical compound is produced when coffee is brewed, but they do know that it is stripped from beverages that are decaffeinated.
Mullan said the large human studies correlating "moderate" coffee consumption — four to five cups a day — with Alzheimer's prevention need to be better understood. The studies showed that people who drank that much coffee in their 40s and 50s had lower incidences of the disease later on.