New York, July 7 (IANS): Explaining a link between marijuana advertising and youth behaviour, adolescents who see advertisements for medical marijuana are more likely to either report using marijuana or plan to use it in future, says a new study.

Youth who reported seeing any ads for medical marijuana were twice as likely to have used marijuana or report higher intentions to use the drug in the future as compared to their peers who had never seen such an advertisement.

"As prohibitions on marijuana ease and sales of marijuana becomes more visible, it's important to think about how we need to change the way we talk to young people about the risks posed by the drug," said lead author Elizabeth D'Amico and a senior behavioural scientist at RAND, a US-based non-profit research organization.

"The lessons we have learned from alcohol -- a substance that is legal, but not necessarily safe -- may provide guidance about approaches we need to take towards marijuana," D'Amico said.

The team analysed information collected from 8,214 students who were asked each year about exposure to medical marijuana advertising, marijuana use and their intentions about whether they would use marijuana in the future.

During the first survey, 22 percent of the students reported seeing at least one advertisement for medical marijuana over the past three months and the rate jumped to 30 percent the following year.

Seeing advertisements for medical marijuana was related to their intentions to use marijuana and their actual marijuana use one year later.

"Given that advertising typically tells only one side of the story, prevention efforts must begin to better educate youth about how medical marijuana is used, while also emphasizing the negative effects that marijuana can have on the brain and performance," D'Amico said.

The study was published online in Psychology of Addictive Behaviours.