Re: 13 year old with depression
I can't tell you anything specific, simply because I don't know enough, but my first question would be - does she know she has a problem and/or does she feel the same way you do about her behaviour? Ask her if she knows why she does some of the things she does, and if she doesn't know, perhaps suggest that there is a motivation behind everything, even if it is subconcious, and see if she is willing to think a little on WHY she does what she does and what she gets out of it. If she does no think she has a problem in any way whatsoever, any kind of solution will be difficult to find.
As far as "treatment" goes, see if you can get her to write in a journal. It doesn't have to be about anything specific, and I certainly recommend that you do NOT read it, and reassure her that you won't ever pry. Get to excercise, at least thirty minutes a day, doing something she enjoys. Involve her in de-stressing activities, such as playing with an animal, reading a book, cooking, or a nice hot bath. Avoid screens - TV, video games, the computer. They are too stimulating to an already overstimulated mind.
Also, speaking from personal experience, she could simply be lashing out in fear. Fear of many things, the future (especially if she has low self-esteem; jr. high is when fear of the future really kicks in), change, fear of not being accepted, especially a fear of not being good enough.
Hope that helps, at least as a jumping point!