Just before the weekend Benoit went and saw his personal doctor. Besides saying Benoit didn't seem anything but normal on Friday and not mentioning the reason for the visit, the doctor did mention he treated benoit with testosterone because Benoit has low testosterone levels. A condition the doctor believes origniated from past steroid abuse.
http://www.ewrestlingnews.com/headlines/184983382.shtml
Plenty of data to suggest steroid abuse messes up your brain and leads to extreme mood swings not just rage (an episode of which may last for a signficant period of time...it need not be a short outburst).