Researchers at the State University of New York's Downstate Medical Center finally have an answer for what causes teen angst: hormones, or more specifically, the hormone THP. The hormone is released in response to stress and, in adults, acts as a tranquilizer to calm brain activity. But in those going through puberty, the scientists say, it has exactly the opposite effect – it produces a state of increased anxiety. Stress also increases anxiety during puberty, due to the paradoxical effects of THP.