epilepsy
"I did a 6 week trial of this and it made me psychotic for about 2 hours once I had gotten my blood level up. High as a kite, aggressive  and talking backwards. So I went off it and had terrible withdrawal in the form of depression and suicidal thoughts. I have temporal lobe epilepsy and I think I am on the more psychotic end of the spectrum so I was more vulnerable to those side effects. I was a second degree black belt at the time. I judge all drugs by my ability to do a decent back kick  without falling over. It failed the back kick test as well."