So, there’s a dark joke about why ECT (Electro Convulsive Therapy) is (mostly temporarily) effective in treatment of depression.

First, you should know, ECT has a strong side effect of amnesia, mostly temporary amnesia.

So, you get ECT, you forget why (you think) your life sucks and your outlook on everything improves, depressive symptoms fade - until your memory comes back.

People in all walks of life get serious depression, including high rates of suicide.