A study published Tuesday in the journal Clinical Psychological Science finds that increased time spent with popular electronic devices — whether a computer, cell phone or tablet — might have contributed to an uptick in symptoms of depression and suicidal thoughts over the last several years among teens, especially among girls.
Though San Diego State University psychologist Jean Twenge, who led the study, agrees this sort of research can only establish a correlation between long hours of daily screen time and symptoms of alienation — it can't prove one causes the other — she thinks the findings should be a warning to parents.
"One hour, maybe two hours [a day], doesn't increase risk all that much," Twenge says. "But once you get to three hours — and especially four and then, really, five hours and beyond — that's where there's much more significant risk of suicide attempts, thinking about suicide and major depression."
Twenge and her colleagues took a hard look at national surveys that asked more than a half million young people, ages 13 to 18, questions that get at symptoms of depression.
Twenge says the surveys asked students to respond to statements such as "Life often feels meaningless," or "I feel I can't do anything right," or "I feel my life is not very useful.
Between 2010 and 2015 Twenge found the number of teens who answered "yes" to three or more of these questions increased significantly, from 16 percent in 2010 to 22 percent in 2015.
By far the biggest increase was among girls — who were six times more likely than boys to report these or other symptoms of depression.
Twenge says the gender difference in the findings might be because the screen experience for boys — typically playing computer games — is a lot different than it is for girls.
"For girls, she says, "a lot of social media revolves around concerns about popularity — am I going to get likes on this photograph, do I look good enough in this picture?
The study also looked at survey responses to questions about suicidal thoughts.
"These include things like depression, thinking about suicide, making a plan to commit suicide and then actually having attempted suicide at some point in the past," Twenge says.
Her team found an increase in suicidal thoughts over that time period and, according to statistics from the Centers for Disease Control and Prevention, an increase in suicide deaths among teens from 1,386 in 2010 to 1,769 in 2015.
Again, the finding about suicidal thoughts was strongest among girls.
Financial stresses and anxiety related to academics and homework are often cited as factors in teen depression. But the overall economy improved between 2010 and 2015, Twenge notes. And surveys suggest the amount of homework given over that time period did not increase.
What did increase significantly, she says, was students' online activity, via computer games and social media.
Her research found that teens who spent the most time on their electronic devices were more likely to also show signs of depression.
Meanwhile, she says, the surveys suggested that hours spent in face-to-face activities — sports, parties, even just going to the mall with friends — seemed to be protective.
Nonetheless, psychologist Andrew Przybylski, an experimental psychologist at the University of Oxford in Oxford, England, takes issue with the researchers' conclusion that online activity is likely behind a shift in teen mood. Przybylski says teens may now simply be more willing to admit they are worried or sad.
"It could be that young people are reaching out, telling parents, telling friends," he says, "and certainly not feeling bad about filling out a survey about how they feel."
And the study doesn't eliminate the possibility that financial strains at home may have contributed to any genuine uptick in depressive symptoms among teens, says Przybylski. Even though statistics suggest the overall U.S. economy improved during the time period of the study, the researchers didn't explore what was happening in individual households in terms of job loss, for example.
Changes in a family's economic circumstances, he says, can be a leading cause of a child's depression.
Twenge responds that though her findings don't prove cause and effect, they are in synch with results from other studies, including some randomized trials — that have found that when people spend less time on electronic devices they tend to be happier and less lonely.
Twenge says the findings should spur continued research and, in the meantime, should serve as a warning for parents that if their teen spends lots of time online they may be at heightened risk of depression.
While the strength of the findings may be controversial, many parents worry about their child's reliance on social media, says Adam Pletter, a child psychologist in private practice in Washington, D.C.
Every day, Pletter says, he sees struggles between kids and their parents. Adults are often way behind, he says, when it comes to technology their kids are fluently using.
"We are digital immigrants," Pletter says. "We did not grow up with internet and cell phones — at least most of us did not. So there's a real dilemma, in that we're in charge of safeguarding our kids and teaching our kids how to be savvy digital users, and we don't have all the skills. Many of us are afraid of the technology."
Pletter offers workshops in person — and online — aimed at helping parents figure out ways to reduce their children's reliance, and in some cases, addiction, to screen time.
ELISE HU, HOST:
We're going to hear about a new study now about teenagers and time spent in front of a screen - computers, cell phones or tablets. This is out in the journal Clinical Psychological Science. It shows screen time might have contributed to an uptick in symptoms of depression and suicidal thoughts among teens, especially girls. NPR's Patti Neighmond has more.
PATTI NEIGHMOND, BYLINE: Researchers looked at national surveys that asked more than half a million teens between 13 and 18 about symptoms of depression. Psychologist Jean Twenge with San Diego State University headed the study.
JEAN TWENGE: Items like, life often seems meaningless. I feel I can't do anything right. And I feel my life is not very useful.
NEIGHMOND: Between 2010 and 2015, Twenge found the number of teens who answered yes to three or more of these questions increased by one-third. And by far the biggest increase was among girls, who were six times more likely to report a symptom of depression than boys. Twenge says that's probably because the screen experience for boys, typically playing computer games, is a lot different than it is for girls.
TWENGE: For girls, a lot of social media revolves around concerns about popularity. Am I going to get likes on this photograph? Do I look good enough in this picture?
NEIGHMOND: The study also looked at suicidal thoughts.
TWENGE: These include things like depression, thinking about suicide, making a plan to commit suicide and then actually having attempted suicide at some point in the past.
NEIGHMOND: Twenge found an increase in suicidal thoughts and suicide deaths - again, mostly among girls. Looking at possible reasons why, she ruled out the economy, which improved overall between 2010 and 2015. She also ruled out stress at school, since the amount of homework she says did not increase. What did increase was online activity.
TWENGE: Playing games on a computer, using an iPod and iPad or a smartphone, using YouTube, using social media sites.
NEIGHMOND: The study found teens who spent the most time on their electronic devices were most vulnerable to depression.
TWENGE: One hour, even two hours doesn't really increase risk all that much. But once you get to three hours and especially four and then, really, five hours and beyond, that's where there's much more significant risk of these suicide attempts and thinking about suicide and major depression.
NEIGHMOND: On the other hand, face-to-face activities, sports, parties, even just going to the mall with friends, seem to be protective. Psychologist Andrew Przybylski at the University of Oxford takes issue with the findings. He says teens may simply be more willing to admit they are worried or sad.
ANDREW PRZYBYLSKI: And so it could be that young people are reaching out. They're telling their parents. They're telling their friends. And they're certainly not feeling bad about filling out a survey about how they feel.
NEIGHMOND: And even though the economy improved during the time period of the study, he says it didn't zero in on individual households.
PRZYBYLSKI: Whether or not the parents in the household were employed or had stable income in this period.
NEIGHMOND: Changes in a family's economic circumstances, he says, can be a leading cause of a child's depression. The findings of this study are in line with a steady stream of research showing women of all ages experience higher rates of depression compared to men. And other studies, including randomized, controlled trials, find when people spend less time on electronic devices, they're happier and less lonely. Twenge says the findings of her study are a warning sign for parents. If their teen spends lots of time online - three, four, five hours a day - they're at a heightened risk of depression. Patti Neighmond, NPR News.
(SOUNDBITE OF KEV BROWN SONG, "ALBANY") Transcript provided by NPR, Copyright NPR.