Since the late 2000s, the mental health of teens and young adults in the U.S. has declined dramatically. That’s the broad conclusion of a new study published in the Journal of Abnormal Psychology.

Between 2009 and 2017, rates of depression among kids ages 14 to 17 increased by more than 60%, the study found. The increases were nearly as steep among those ages 12 to 13 (47%) and 18 to 21 (46%), and rates roughly doubled among those ages 20 to 21. In 2017—the latest year for which federal data are available—more than one in eight Americans ages 12 to 25 experienced a major depressive episode, the study found.

The same trends held when the researchers analyzed the data on suicides, attempted suicides and “serious psychological distress”—a term applied to people who score high on a test that measures feelings of sadness, nervousness and hopelessness. Among young people, rates of suicidal thoughts, plans and attempts all increased significantly, and in some cases more than doubled, between 2008 and 2017, the study found.

These findings were based on data collected from more than 600,000 people by the National Survey on Drug Use and Health, an annual nationwide mental-health survey conducted by a branch of the U.S. Department of Health and Human Services.

“I think this is quite a wake-up call,” says Mary Helen Immordino-Yang, a professor of psychology and education at the University of Southern California (who was not affiliated with the new study). “These findings are coming together with other kinds of evidence that show we’re not supporting our adolescents in developmentally appropriate ways.”

One of the study’s authors agrees. “There is an overwhelming amount of data from many different sources, and it all points in the same direction: more mental health issues among American young people,” says Jean Twenge, a professor of psychology at San Diego State University and author of iGen, a book about how technology affects the lives of young people.

What’s causing today’s young people so much anguish? “This is always a tough question to answer, as we can’t prove for sure what the causes are,” Twenge says. “But there was one change that impacted the lives of young people more than older people, and that was the growth of smartphones and digital media like social media, texting and gaming.”

While older adults also use these technologies, “their adoption among younger people was faster and more complete, and the impact on their social lives much larger,” Twenge says.

While not all the evidence is consistent, a substantial amount of research has found associations between heavy technology use and poor mental health outcomes among adolescents and young adults. Research aside, many parents, teachers, guidance counselors and others who work with young people say social media and heavy technology use are a problem.

The way young people communicate and spend their leisure time “has fundamentally changed,” Twenge adds. “They spend less time with their friends in person and less time sleeping, and more time on digital media.”

Immordino-Yang echoes many of Twenge’s concerns. “There’s a lot we don’t know, and we can’t say conclusively what’s driving these [mental health] trends,” she says. “But in the real world when dealing with the health of children, you need to make your best guess and move ahead before things are unequivocally proven.”

“It makes sense,” she says, “to pay attention to adolescent behaviors we know are changing and to target those behaviors for intensive scrutiny, and in the meantime to have [young people] engage in behaviors that don’t lead to poor well-being.” She highlights unfettered access to social media as one recent and potentially unhealthy change. “There’s this overload of information and stimulation and a much bigger sphere of influence that they’re being exposed to,” she says. “Given what we know about adolescent development and vulnerability and the intensive need for intimate and healthy social connection during these years, you can see how social media may not be developmentally appropriate.”

But other experts say the existing evidence doesn’t support singling out social media or technology as a culprit. “When it comes to social media and depression, the findings are all over the place,” says Laurence Steinberg, a distinguished professor of psychology at Temple University and an expert in adolescence.

“I think every generation of adults tries to pin a negative trend they see in young people on whatever the current technological fad is,” he says. While he agrees that the data show depression is rising among young people, he says he doesn’t see “a clear cost” associated with technology or social media use.

“Certainly there are some stressors that are inherent in social media use, but there are other stressors as well,” he says. He mentions increased competition to get into college and “parents hovering” as potential factors. “It’s probably not one thing,” he says, “but the cumulative impact of a lot of things.”

Twenge says it’s tough to compare the current figures to historical rates of youth depression—mostly because historical statistics either don’t exist or aren’t comparable to current measures. But there is data on youth suicide going back several decades. “There was a big peak of teen suicide in the early 1990s that got a lot of attention,” she says. According to the latest data, current teen suicide rates are now significantly higher than those 1990 highs, she says.

The CDC has also issued reports showing that rates of suicide among young people jumped 56% between 2007 and 2016, after declining between 1999 and 2007.

“There should no longer be any doubt,” Twenge says. “There is a mental health crisis among American teens and young adults.”

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