Previous studies have found that more exposure to movie smoking increases teens' risk of starting to smoke, according to background information in the article. "However, not all adolescents who try smoking go on to become dependent smokers; half of high school seniors have tried smoking at some time, but only 7 percent are current daily smokers of half a pack or more," the authors write. "Little is known about the factors that discriminate adolescents who progress to dependent smoking from those who do not."

James D. Sargent, M.D., of Dartmouth Medical School, Lebanon, N.H., and colleagues surveyed 6,522 U.S. adolescents age 10 to 14 about their smoking and movie-watching habits in 2003. The researchers coded displays of smoking in 532 hit movies in the five years prior to the survey, then asked the teens if they had seen a random selection of 50 of these movies.

They then created a measure of smoking exposure by adding the number of smoking occurrences in the portion of those 50 movies that the participant had seen, dividing by the number of occurrences in the 50 movies, and multiplying that by the number of smoking episodes in all 532 movies. Follow-up interviews to reassess smoking status were conducted after eight months, 16 months and two years.

At the beginning of the study, 5,637 (90 percent) of the teens had never smoked, while 33 (0.5 percent) had smoked more than 100 cigarettes. By the two-year follow-up survey, 125 of the participants had become established smokers. Adolescents who were below the midpoint of movie smoking exposure were less likely than teens who were above the midpoint to have smoked more than 100 cigarettes. The association remained significant after the researchers considered other factors related to teen smoking, including age, smoking by a parent or friend and sensation-seeking qualities.

The exact mechanism for this link is unclear, the authors note. "The context of current theory and research suggests the most plausible explanation is that frequent exposure to smoking cues in movies leads to more positive expectancies about effects of smoking, more favorable perceptions of smokers and a greater tendency to affiliate with teens who smoke, all factors that increase risk for smoking," they write.

"Combined with previous findings showing that young persons who view more smoking in movies are at increased risk for initiating cigarette smoking, the present findings heighten concern about the public health implications of movie-smoking exposure by linking it with an outcome that predicts smoking-related morbidity and mortality in the future," the authors conclude.

Reference: Arch Pediatr Adolesc Med. 2007;161(9):849-856.

This work was supported by a grant from the National Cancer Institute, the American Legacy Foundation and a grant from the National Institute on Drug Abuse.

Note: If no author is given, the source is cited instead.

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