MODEL RELEASED. Depression. Depressed teenage girl sitting on the floor indoors beside a pad of paper and a pencil. She could be writing a suicide note. She may be withdrawn, sad or have reduced emotional well-being. In teenagers, depression may be caused by loneliness, bullying, abuse, confusion resulting from the onset of puberty and disruption to family life. Alternatively, this girl could suffer from agoraphobia, an intense fear of open and public places.