@kingturtle
I spent more than 1,000 hours researching depression over the years, including reading studies, reading books by elite psychiatrists-pharmacologists and going to depression forums.
If I remember correctly(its been a few years since I researched it), there is 5 general aspects of depression. And different drugs are better depending on the aspect.
1.) Neuro-Vegetative Depression - this is appetite, sleep & sex drive. Basically if you have trouble staying asleep like nightmares, if you have no appetite and no interest in sex this is an aspect you have.
2.) Anxious Depression - this is like you feel anxious going outside, being around people, something like a loud noise out of nowhere gets your heart racing, which is normal.. but you take a long, long time to calm down. And the extent of how anxious you get is over the top.
3.) Sadness Depression - I believe this is Acetylcholine based. An overactive Acetylcholine system and you have like tears just behind your eyes all the time, and feel depressed.
4.) Ahedonia Depression - this is like no matter what you don't feel any pleasure or happiness. It is basically your dopamine system is not activating to reward you for good things happening to you.
5.) Anergic Depression - this is a lack of Norepinephrine. This is energy, drive, motivation.