If the dude is on ANY anti-depressants and was drinking alcohol then you can safely blame the anti-depressants. They state on the box NOT to mix them with alcohol, and there is a reason. They send you bat shit. I know, because I used to be on them and drank once and got messed up beyond belief. You do things you wouldn't normally do, and in your head nothing is wrong with it, yet to anyone who's not you, you seem crazy.
So blame the drugs if he's on them, if not, then run.