http://www.medscape.com/viewarticle/850899?src=confwrap

Anyone who suffers from any form of chronic pain can lose their ability to focus. It doesn’t mean they had ADD to begin with or that ADD caused their pain. I can concentrate on a lot of different things when I’m well-rested and not in a terrible amount of pain, but when I’m in a full-on flare up, my attention span is close to that of a house fly. So, read this and think about it, talk to your doctor, but don’t make assumptions about yourself. Also, if you suffer from chronic pain and you’re 100% calm all the time, I’d like to know precisely what your doctors are offering you and where I can get it.