Answer:
False.
Lets say something with MDD (Major Depressive Disorder) gets on the news for committing a horrible crime and the news uses that as a way to excuse away their behavior and/or to say everyone with MDD would act that way.
I, as someone who has been professionally diagnosed with MDD for over a year now, would know logically that my mental illness, while affects some of my actions, makes me more self destructive. Meaning the most I'll do to other people in pursuit to harm myself would be to push them away from me and try to get them out of my life if they are good for me.
My MDD doesn't make me violent towards anyone but myself.
However if someone has only ever heard the mention of that mental illness through the news now they will equate it with violence and harm to others. Giving them a perception of me when I tell them my diagnoses that I am violent and harmful and I'll eventually do something to hurt them or someone else, when that simply is not true.