We ask people with impaired reason to consent to treatment to try to re-establish their sanity. Are they even capable of making such a decision?
I was psychotically manic, suicidal, and engaging in self-injury when my doctor decided I needed electro-convulsive therapy. I got it. I received a couple dozen treatments that messed with my memory but did stop the episode that nearly killed me.
Somehow, at this time in my life when I was a raving lunatic, I was asked to consent to treatment and, apparently, I did.