You're confused about words; I recommend you read A Human's Guide to Words, summarized by 37 Ways Words Can Be Wrong. I'll try and give a quick explanation that will hopefully be helpful. Depression is not a low-level part of reality; it's just a convenient label on our maps. The entire meaning - literally all of it, by the DSM definition - is that the person possess a certain number of symptoms from a list. If you know they express those symptoms they are depressed; if you know they are depressed you know they express those symptoms. That is, literally and entirely and without exception, everything that is true about the word depression as defined by DSM. There is no further question, no further information. There is no precedence, no ordering to the events between being DSM-depressed and having the symptoms. DSM-depression is in the map, not the territory, so there is no causality involved.

Actually, I'd like to put this metaphor in terms of 2 sets of maps. The first map just says "DSM-depressed" on a person. That map is compact; it enables compressed storage of lots of information, although it certainly is not lossless. When you pull that map out, and read it, and you know what DSM-depression means, you can then draw a second map. This map is a little bit more precise; it has a list of symptoms, and says they express some number of them. But you can't then combine the maps, and write a single map which both contains the list of symptoms and the DSM-depressed tag. It would be redundant; there would be repeated information. The 2 maps are describing different levels of organization. It would be like looking at an airplane and saying "do the wings, engine, etc. cause this to be an airplane, or does the fact that it is an airplane cause the wings, engine, etc." It is nonsense to ask the question; in the territory there is no "airplane" label, and for that matter no "wings" or "engine" labels either. Don't confuse your map with a more detailed map, nor with the territory itself.

One other note is that you're acting like the word "depression" has a meaning, no matter what a given definition defines it to mean. If I defined "depression" to mean "water", and used it consistently, and made it clear to you what I meant, I would be committing an error with words; but that error would not be that "depression" doesn't really mean "water".

EDIT: Forgot to say this, but I'm tapping out. I'd recommend not clogging up the comment thread any more than we already have. If you still have questions feel free to PM me, and I will respond in more depth, but unless you've read the linked sequence and understood at least most of it (or put a genuine effort into trying) I'll probably just point you back to it.