Paula - and everyone else - I have been reading that awesome book the Compassionate Mind about how genes, chemicals, neurons and evolution created our emotional states and then the second half of the book is ways to be able to turn on the more pleasant healing systems in the body/brain and turn off the PTSD ones- and he writes about how alcohol makes people act in different ways - some fall asleep, some fight, some get funny, some get depressed - and that scientists do know that antidepressants are the same way.  Everyone's body chemistry is different.  I just wanted you to know that you are right and that scientists do know this,  The more I study modern, cutting edge research on the brain, the more justified I feel, the more all I ever felt is validated.