While ten cups of coffee daily is a good indicator of an addiction, I have seen people wean themselves off other addictions using that much coffee for a period of time. An easy way to reduce is to opt for the "half the caffeine" products. If that isn't avaliable on your grocer's shelves, you can make your own by purchasing a jar of each - regular and decaf - and mixing them together. This way if ten cups is still consumed, it would only be the equivilent of five cups caffeine-wise. Stopping completely will most likely produce a terrific headache, but that only lasts a few days according to the people I have heard from who cold-turkey quit.
Here is one of a number of sites I found searching the web that outlines the effects of excessive coffee consumption:
http://www.nlm.nih.gov/medlineplus/e...cle/002445.htm