As well as causing respiratory problems, smoking cigarettes may lead to depression in teenagers, according to a report published in Pediatrics (2000;106(4):748-55).

The study followed 15 000 United States teenagers over a year, and found that teenagers who smoked were more than twice as likely to develop high depressive symptoms than those who were non-smokers (10.5% v 4.8%).

The heaviest teen smokers seem to be more at risk than those who smoke only occasionally. Twelve per cent of teenagers who smoked at least one pack of cigarettes a day reported depressive symptoms after a year. The study also found that while sociodemographic factors, including age, gender, household income, and parental education, were not significantly associated with a progression to teenage heavy smoking, race was. White teens were found more likely to become moderate to heavy smokers than other racial groups of the same age.

Most importantly, the study found that high depressive symptoms in teens were not an independent predictor of subsequent smoking habits, and therefore claims that depression in troubled teens is not a cause of smoking initiation or progression. The authors also suggests in the study that the development of depressive symptoms in smokers may be due to the effects of nicotine, or another smoking byproduct, on central noradrenergic receptor systems.

Amanda Sandford, research manager for ASH (Action on Smoking and Health), agreed with the study authors on the need for good advice being given to teenage smokers. "Despite the fact that smokers perceive the habit as pleasurable, smoking appears to have a depressive effect," she commented in response to the study. "Young people who say they smoke to relieve stress are deluding themselves. Smoking is not going to help; on the contrary it is likely to make them feel even more anxious or depressed."