Hasn’t depression sometimes been characterized as anger turned inward? So that would make introverts more likely to kill themselves... and extroverts more likely to kill others???

I had no issues with depression until I developed physical health issues. Feeling like @#$% all of the time @#$%s with your head.

That is spot on for me.

I am personally under the influence that everyone suffers depression ( both introverts and extroverts) but extroverts have more outlets for depression there by causing skewed results of the sufferers of depression. I surmise if I had more friends ( or any friends) I wouldn't be as depressed as I presently am. Another words I let things just fester and I tend to deal with my problems myself more then say an extrovert would. Anxiety I think for me is the root cause of most of my depression. I think also statistically introverts have a higher rate of suicideal idealizations and probably off themselves at a higher rate. Here is an article from about a year ago which would back what I am thinking I believe.
[psychologytoday.com]

Interesting. I personally suffer from chronic (now well managed in remission) depression. I would attribute this to our awkwardness and sense of inadequacy in social situations but that is absolutely only a guess.