I've nearly been a murder-suicide victim due to esketamine, so yes, it definitely exists. In fact, they screen out people out of the trials with psychosis due to this known potential side-effect. They also remove people from the trials for things like that.

It's too bad, because other than that side-effect, it was doing a lot of good.

“Among people without a lifetime extremely stressful event…”

It's not unlikely that people fitting the context of this article, i.e. clinical depression, have had a lifetime extremely stressful event, causally or consequentially.