Your concussion symptoms have a lot to do with your health BEFORE the injury.

[@LisaMonks444]

What about Me/cfs and fibromyalgia?

[@drmarkheisig]

There's not specific research in that area, as far as I know (e.g., Fibro before = Worse fibro after... we're not sure). Generally, though, we see pre-existing concerns come up. Like stirring the mud.