I've always thought that one big cause of depression is the reaction to life/culture/society. Same goes for anxiety.

We are seeing the rise of depression even with all the advances we have in our first world country. Once again I point to our society where we are devoured with celebrity culture, constant negative news stories (which help bring on anxiety), seeing how other people are enjoying or doing better in their lives than you are..

Seeing that day after day for years on end I would imagine has to have some sort of effect on people.

Then on top of that people are just given benzo's or anti-depressants as a way to just dull their problems(if it even works for them) and it never gets them to address the issue of their depression. And if they want to get off most people aren't even told from the start of the dangers and withdrawals that can happen with anti-depressants.

This is just one of the symptoms that I see that can start depression, along with what we eat/exercise and genetics.