What this suggests to me is that what we diagnose as "depression" has multiple causes, and current antidepressants are fairly effective at treating at least one

What this suggests to me is that what we diagnose as "depression" has multiple causes, and current antidepressants are fairly effective at treating at least one of them. It's as if we had a single category for "breathing trouble" and consistently treated it with antibiotics. Sometimes it's bacterial pneumonia and that works very well. Often it's emphysema or lung cancer, and antibiotics don't help.