Adolescent smoking and depression: Which comes first?

Despite the well-known health risks of smoking, adolescents continue to smoke at alarming rates. Smoking is also known to be associated with depression, but the direction of this relation is unclear. This study used data from the National Longitudinal Study of Adolescent Health (Add Health) to evaluate the direction of the relation between cigarette smoking and depression among adolescents. A total of 14,634 adolescents (7132 males and 7502 females) completed in-home surveys in 1995 and 1996 and were split into four smoking status groups. Adolescents who were Starters, Quitters, and Maintainers were found to be 1.5, 1.4, and 2.0 times more likely, respectively, than Nevers to be depressed at Time 2. In addition, females showed a striking pattern of increases in depression around the onset of smoking and decreases around the time of quitting. While these findings do not prove that smoking leads to depression, they are consistent with such a prediction.