system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: People who have depression caused by a chemical-imbalance, why do antidepressants not work for all of them?

I’m not talking about people who have genuine reasons to feel depressed. Just people who have an unfortunate chemical imbalance in their brain.
gpt
The "chemical imbalance theory" was thrown out long ago, but the medications are still used. The real reason those medications only work for some is because we've never genuinely understood the roots of depression. It isn't as simple as a chemical imbalance. If there's no imbalance, a pill that's meant to bring a balance back isn't going to do much of anything.