"What are the factors that create depression?"Look deeply into your own experience and try to find the cause of your current state of mind. Causes for one's state of mind are different for everybody. However, what is similar for those who have depression is the manner in which they respond to stimuli. For my own experience with depression I could describe it as this:
"I'm not happy enough to know why I am depressed and that makes me depressed."Clearly, it seems like it is a circular type of existence that begins with grasping towards being happy.
I paraphrased the above from something I was going to post on a discussion forum. Somebody was asking about depression, but I thought that it would be more appropriate for me to post it here instead of there.