--it seems fairly evident that having a condition that casues pain and disability can put a damper on one's creativity, and it can certainly impact one's ability to focus and concentrate.

I suspect, though, that reports of flattened affect and motivational difficulties are more likely to be the result of many of the meds we take, especially of the anti-seizure variety. Their tendency to make us dizzy, fatigued, and made more lethargic in our interests (and crave carbohydrates, as if we're going into hibernation) are well-documented.

One of the good side-effects of taking B-complex, and especially B12, is that (at least for me and some others I've spoken with) they help to balance and counteract this tendency.