Young teens who watch a lot of movies featuring alcohol are twice as likely to start drinking compared to peers who watch relatively few such films, reveals research published in the online journal BMJ Open.
And these teens are significantly more likely to progress to binge drinking, the study shows.
The findings prompt the researchers to suggest that Hollywood should adopt the same restrictions for alcohol product placement as it does for tobacco.
They base their findings on a representative sample of more than 6500 US teens between the ages of 10 and 14, who were regularly quizzed about their consumption of alcohol and potentially influential factors over the next two years.
These factors included movie viewing and marketing; the home environment; peer behaviour; and personal rebelliousness.
The teens were asked which randomly selected 50 movies they had seen from among the top 100 US box office hits in each of the preceding five years, plus 32 films grossing more than US $15 million in the first quarter of 2003--the year of the first survey.
The number of seconds of on-screen alcohol use, including product placement, in each of these 532 films was measured by trained coders. Given the movies they reported seeing, adolescents had typically seen an estimated 4.5 hours of on screen alcohol use and many had seen in excess of eight hours.
Around one in 10 of the teens (11%) said they owned branded merchandise, such as a T shirt or hat with the name of a beer/wine/spirit on it. And nearly one in four (23%) said their parents drank alcohol at least once a week at home; 29% said they were able to get hold of alcohol at home.
Over the course of the two years, the proportion of teens who started drinking alcohol more than doubled from 11% to 25%, while the proportion who began binge drinking--defined as five or more drinks in a row--tripled from 4% to 13%.
Parents who drank at home, and availability of alcohol in the home, were associated with taking up drinking, but not progression to binge drinking.
Exposure to alcohol in movies, owning branded merchandise, having friends who drank, and rebelliousness were associated with both.
After adjusting for factors likely to influence the results, teens who watched the most movies featuring alcohol were twice as likely to start drinking as those who watched the least. And they were 63% more likely to progress to binge drinking.
Alcohol in movies accounted for 28% of the proportion of teens who started drinking between surveys and for 20% of those who moved on to binge drinking.
The association was seen not only with movie characters who drink, but also with alcohol product placement, suggested the authors.
"Product placement in movies is forbidden for cigarettes in the USA, but is legal and commonplace for the alcohol industry, with half of Hollywood films containing at least one alcohol brand appearance, regardless of film rating," they write.
They point out that the depiction of smoking in movies has fallen since it became a public health issue and the subject of industry monitoring, and suggest that alcohol in movies "may deserve similar emphasis."
Hollywood has responsibilities further afield, given that half its movie revenues come from overseas, they add.
"Like influenza, images in Hollywood movies begin in one region of the world then spread globally, where they may affect drinking behaviours of adolescents everywhere they are distributed," they write.