The U.S. has spent millions of dollars since the 1980s on anti-drug ads. But research shows that some of these older public service announcements might be counterproductive. Now that the ads are shifting to reach teens who want to rebel, new studies show they may actually be more effective.

Shaunacy Ferro wrote about these TV spots in Popular Science. She explains that in some cases, the old ads like "this is your brain on drugs," may have encouraged teens to try drugs.

"Subconsciously, kids would start to think, 'Hmm, well I don't really know what doing drugs is like. Maybe I should try it,'" Ferro says.

"Kids are a lot smarter than we give them credit for," he says. "Because they'll begin to ask the question, well from where is the influence coming?"

Read the full article at npr.org