I'm not saying that a depressed person wouldn't want to understand how depression works, just that they don't necessarily want to, and it's wrong to be annoyed that they don't.
I also don't believe that doctors really talk what the 'various causes are'.
I've been depressed, very much so, and I've read books that summarize scientific reading about depression like The Upward Spiral[0], and I feel like they miss the point, somehow. Like: we're great at finding treatments and things that work for individual people, but I sort-of think that the problem with depression is fundamentally everyone else, ie, 'society is sick', and we treat it as a personal problem because well of course doctors can't prescribe fixes to society, but they can for a person, so it's all stopgaps that don't address the "real problem".
I think that often depressed people have an idea of this -- that it is the existence around them that is sick, somehow -- and so no amount of suggestions (which indeed might actually help) quite gets to the bottom of that because it is the world that is fundamentally wrong. (Or specifically it is the nature of how they currently fit into the world.) From a treatment standpoint yes of course they should do the things that will probably help them, and people around them should be empowered to get them to do the things that will help them. But for the person that is struggling that really doesn't feel like the answer, and I think that they're not wrong.
(By 'society is sick' I mean that the person does not, for whatever reason, exist in the mentally healthy setting that their brain was 'designed' to exist in -- a healthy community, the right kinds of relationships, the emotional mentors and sources of wisdom that provide the right kinds of useful guidance, a body that works the way that it's supposed to, physically and mentally, etc; and a world around them that makes sense, that they can feasibly cope with, which is exactly the opposite of the nihilism induced by news of politics and global tragedies.)
