Scott Alexander in Astral Codex Ten:
Everyone knows politics makes people crazy. But what kind of crazy? Which page of the DSM is it on?
I’m only half joking. Psychiatrists have spent decades developing a whole catalog of ways brains can go wrong. Politics makes people’s brains go wrong. Shouldn’t it be in the catalog? Wouldn’t it be weird if 21st century political extremists had discovered a totally new form of mental dysfunction, unrelated even by analogy to all the forms that had come before?
You’ll object: politics only metaphorically “makes people crazy”; we just use the word “crazy” here to mean “irrational” or “overly emotional”. I’m not sure that’s true.
More here.