If you watch the commercials for any of these drugs, they all tell you that some of the side effects are depression and suicidal tendencies, along with a long list of other horrible effects.
You're told if you experience any of them, you're to call your doctor. I'm pretty sure that someone who is on these drugs had some sort of mental issues in the first place, and then has side effects making things worse, calling the doctor is not going to be on their to-do list.