American teens using less drugs, smoking fewer cigarettes and drinking less alcohol, which begs the question – what are teens doing instead?

In 1999, 1 out of 20 high school sophomores tried cocaine. Seventeen years later, cocaine use is down to only 1.3 percent of 10th graders. But cocaine use is not the only illicit substance declining among teens. In 1996, nearly 1 out of 5 eighth graders reported getting drunk in the past year. Now, only 5.7 percent of twelve year olds report getting drunk.

Published in the 2015 National Institute of Health annual study, Monitoring the Future survey, researchers found that there is a major shift in teen behavior and drug use. The studies showed a continued decline in the many illegal drugs including alcohol, tobacco and marijuana. In addition, prescription medications were also on the decline. Researchers surveyed middle school students and high school students as part of an annual survey monitoring drug use among teens.

What’s interesting is that as marijuana becomes legal across the country, the number of eighth graders using marijuana in the past month declined from 6.5 percent to 5.4 percent. This maybe due to the attitudes towards marijuana. In fact, according to the study 44 percent of 10th graders believe marijuana smoking is harmful.

However, four years later, marijuana use in the past month among high school seniors is nearly 25 percent with 22.5 percent reporting using the drug and 6 percent report using it daily. In addition, states with medical marijuana laws also report higher weed use among teens (38.3 percent) in comparison to states without medicinal marijuana laws (33.3 percent).

Nora D. Volkow, M.D., and director of the National Institute on Drug Abuse (NIDA) explained that public health prevention efforts and public policy changes are helping decrease drug use among teens. But, that does not mean Americans should celebrate. Dr. Volkow argues that the 6 percent of high school teens using marijuana daily is worrisome.

“However, when 6 percent of high school seniors are using marijuana daily, and new synthetics are continually flooding the illegal marketplace, we cannot be complacent. We also need to learn more about how teens interact with each other in this social media era, and how those behaviors affect substance use rates,” Volkow explained.

So what are teens doing instead? A 2016 study by Business Insider found that teens are getting phones earlier and spending approximately six hours per day on their cell phone. In addition, reports suggest that many teens are spending every minute of their waking lives in front of some sort of screen, either a cell phone, computer or a television. In addition, studies have shown that  Snapchat is one of the most popular apps among teens, followed by Netflix and Instagram. What’s not as popular among teens? Facebook.

With an entire generation living vicariously through social media absent of any mind altering substances, it truly begs the question – are teens addicted to social media and not drugs? A May 2016 UCLA researchers discovered that a teen’s brain reward regions becomes excited when teenagers see high numbers of “likes” on their photos.

The study analyzed 30 different teens ages 13 to 18. Researchers told the teens they will be participating in a small social network, similar to Instagram. In the experiment, the researchers showed the teens hundreds of photos on a computer screen, including 40 photos the teens submitted. Meanwhile, researchers used an fMRI to see which parts of the brain were activated while the teens browsed the social network. Researchers found that the reward part of the brain, the same part of the brain that becomes excited when someone eats candy, or uses a prescription opioid such as fentanyl or an illegal drug such as heroin, became ignited when they teens saw their photos had “likes”.

The nucleus accumbens is known to be the reward pathway for several prescription medications and illegal drugs including “heroin”. When a heroin user injects the drug, high levels of the neurotransmitter Dopamine are sent to the nucleus accumbens causing an euphoric feeling. The same reward pathway occurs when teens see a large number of “likes”.

While the study did not suggest social networks were as addictive as heroin, researchers did note that large number of “likes” had a larger effect on the teens than just a few. So much so that social media can impact behavior. Researcher in the UCLA study, Lauren Graham explained, “If your teen’s friends are displaying positive behavior, then it’s fabulous that your teen will see that behavior and be influenced by it.”

Graham also added that it is important for parents to be aware of what their teens are seeing on social media and who they are friends with.

“It’s important for parents to be aware of who their teens interact with online and what these friends and acquaintances are posting and liking,” Graham explained “In addition, teens’ self-identity is influenced by the opinions of others, as earlier studies have shown.”