New evidence suggests that two anti-drug campaigns may help curb marijuana use among early teens.

A study looked at self-reported exposure to two anti-drug campaigns and measured the frequency of drug use in teens from 20 middle-school communities. Messages that highlighted teen autonomy and aspirations were more effective than previous campaigns with more negative focuses.

Aiming to measure the effectiveness of an experimental campaign “Be Under Your Own Influence,” Ohio State University professor of communication Michael Slater said he and his colleagues couldn’t help but study the national campaign “Above the Influence” as well. The researchers realized that the two unrelated campaigns were launched at the same time and promoted similar messages.

NEWS: Teens Get High Off Digital Drugs

The results of the “Be Under Your Own Influence” campaign “are swamped by the effects of the national campaign,” Slater told Discovery News. He said both campaigns focused on the inconsistencies of teens’ personal autonomy and how drugs affect that balance.

The “Be Under Your Own Influence” campaign, which focused on mostly print materials, was studied by using four different setups. Students were directly exposed to the campaign in the classroom, exposed through media in the local community or exposed to both or neither. The team found teens who reported exposure to the “Be Under Your Own Influence” also reported the lowest marijuana use the most when community involvement was added to the picture.

On the other hand, they found the “Above the Influence” national campaign could reduce an early teen’s chance of trying the drug simply through exposure. Click here to watch the organization’s current ads.

“We also asked about fake campaigns to rule out fakers,” Slater added. This way, students who reported to have been exposed to non-existent ads and made-up drugs were ruled out from the sample.

Though the findings point to the success of anti-drug ads, Slater isn’t afraid to point out the research’s weaknesses.

NEWS: Is Television Harmful for Children?

“When you don’t have the control of experimental design,” he said, “there’s always the possibility of alternative explanations.”

Also, scientists are unsure whether the same patterns exist in highly urban school environments, as the majority of the research focused on communities smaller than your typical metropolis. Slater also said future research will need to use larger sample sizes to further confirm these findings.

As of 2009, roughly 7 percent of 8th-graders had used marijuana within one month of being asked, according to a recent survey.

The research is featured in the March issue of Prevention Science.

Photo credit: iStockphoto/Thinkstock