Seventh graders who watched these ads, especially girls, were more likely to start drinking.
And boys who liked the advertisements were more likely to develop alcohol-related problems, Grenard's group found.
Grenard believes the ads influence seventh graders to drink as they move on in school. Of the seventh graders recruited for the study, 57 percent had never tried alcohol or only a little, he noted.
"Therefore, we were able to assess exposure to advertising before many students began to drink alcohol regularly," Grenard said.
Other experts agreed that schools, parents and doctors should help children understand that what they see on TV or on the Internet isn't always true.
"This study contributes to existing research on advertising and alcohol use among youth by showing an association with exposure to alcohol ads on TV and later alcohol use as well as problem behavior due to drinking," said Jennifer Manganello, an associate professor at the University at Albany School of Public Health.
Based on these findings and earlier research, "media literacy programs" are needed to educate youth about advertising claims, she said.
"Also, parents should be familiar with where their children may be exposed to alcohol ads, including places like social media sites and mobile phones," Manganello said. They should also discuss alcohol advertising with them, she added.
But Dr. Metee Comkornruecha, who practices adolescent medicine at Miami Children's Hospital in Florida, doesn't believe liquor ads play an overwhelming role in getting kids to drink.
"I think it's a minor role," he said. Total media exposure, however, does have a significant role, and this includes what children see in movies, TV programs and online, he added.
Comkornruecha doesn't think liquor ads should be banned from TV as tobacco ads are. "A lot of responsibility is to teach kids about media literacy," he said.
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