Having just entered the discussion, I am not sure if this point has been brought up. My initial reaction when hearing this report on NPR, i.e., much use of the Internet causes depression, was to wonder if the people who are depressed were depressed before they got involved in internet use. I can see this happening, someone who is introverted, someone who is a hermit-type person, who is somewhat depressed, and who is not actively seeking public social life, this type of person would really be drawn to the anonymity of the computer and the internet. This sort of person would be depressed to start with, and increased use of anything like this would add to it. I see it as a form of inertia. I am not a psychologist or psychology student, just a very interested observer in human nature.