Do antidepressants change our biology and does it that mean that people can never be the same as before?

I doubt it. What I DO know is that people who are actually depressed lose brain cells from it, and can end up taking their lives for no good reason whatever (and there aren't many good reasons for suicide in any case.) In fact, antidepressants are believed to help PTSD victims grow lost brain cells back. Don't hesitate to use them, with talk Rx, if they're going to be helpful. The alternative ARE "never same"