A hundred years ago, the poet Gerard Manley Hopkins' Jesuit-based understanding of what I would call his depression may well have served him as well as prozac will ever serve me. I never underestimate the uses of belief. I wouldn't want to be responsible for what might happen if she were to be put on prozac. There are no cures free of context. Anyone can experience a major depressive episode, often, but not always, triggered by life changes or events of loss.
Some people become directly or indirectly self-destructive.
I have some information about nutrition and some of its effects on mood. On a.s.d, a poster recently wrote in about his experience with negative ion therapy, which will be of interest to anyone who spends a good deal of time on a computer. I also have a long, quite informative booklist on depression, garnered from a.s.d. In Peter Kramer's book Listening to Prozac, he raises related questions of temperment and the demands of the culture we live in. I recommend it, as a source for thinking about depression and personality, and the state of late 20th century psychiatry.