Sometimes it is expressed through crippling anxiety or other emotions.
(Sorry, I changed your answer to make it fit for me.)
That's how my depression was. It was more or less due to my crippling anxiety and overloaded emotions. It was so bad that I literally wanted to just die. I couldn't handle the amount of stress I was constantly under. It was hurting me so much. I would constantly due certain behaviors I wouldn't normally do such as head-banging. I also used to self-harm all of the time. It wasn't in a sense where I wanted to bleed. I just took a tack and scraped at my skin until it left a painful mark on my wrist. :/
It got to the point where it was interfering with my daily life. I couldn't write, listen to music... or anything because I just felt so overloaded and depressed all at the same time I guess. It was the most awful feeling ever, and all I wanted was for it to go away. I used to also think very badly of myself. If I would hurt other people or piss them off or something, I would beat on myself, call myself a monster and sob really hard. It was just the worst feeling ever. I always thought of myself as being a failure at the time.
For a while, I did go into a slight state of depression. It wasn't the kind I mentioned above, but in an extent where I didn't know who I was. It started not long after getting out of a relationship after my ex left Facebook without even telling me it was over then losing my friends not long after... only to realize they were fake. Now that I'm back into visual kei and have my hero Takeru to look up to, things are getting better for me now. I have some pretty amazing friends and the greatest boyfriend/soul mate in the world. I'm grateful for the things I have, even if they aren't really perfect. I'm starting to value my life more and live it as much as I can before it's too late.
I take medication for mine as well. It's an anti-psychotic, but it helps. I have not had a single episode of depression since I started taking it. It's improved my life so much more. I'm able to do more things, or at least most things I couldn't do during that state of depression I was in.