Journalists should stop saying that the evidence is just correlational
A big story last week was the partial release of the CDC’s bi-annual Youth Risk Behavior Survey, which showed that most teen girls (57%) now say that they experience persistent sadness or hopelessness (up from 36% in 2011), and 30% of teen girls now say that they have seriously considered suicide (up from 19% in 2011). Boys are doing badly too, but their rates of depression and anxiety are not as high, and their increases since 2011 are smaller. As I showed in my Feb. 16 Substack post, the big surprise in the CDC data is that COVID didn’t have much effect on the overall trends, which just kept marching on as they have since around 2012. Teens were already socially distanced by 2019, which might explain why COVID restrictions added little to their rates of mental illness, on average. (Of course, many individuals suffered greatly).
Most of the news coverage last week noted that the trends pre-dated covid, and many of them mentioned social media as a potential cause. A few of them then did the standard thing that journalists have been doing for years, saying essentially “gosh, we just don’t know if it’s social media, because the evidence is all correlational and the correlations are really small.” For example, Derek Thompson, one of my favorite data-oriented journalists, wrote a widely read essay in The Atlantic on the multiplicity of possible causes. In a section titled Why is it so hard to prove that social media and smartphones are destroying teen mental health? he noted that “the academic literature on social media’s harms is complicated” and he then quoted one of the main academics studying the issue—Jeff Hancock, of Stanford University: “There’s been absolutely hundreds of [social-media and mental-health] studies, almost all showing pretty small effects.”
In this post, I will show that Thompson’s skepticism was justified in 2019 but is not justified in 2023. A lot of new work has been published since 2019, and there has been a recent and surprising convergence among the leading opponents in the debate (including Hancock and me). There is now a great deal of evidence that social media is a substantial cause, not just a tiny correlate, of depression and anxiety, and therefore of behaviors related to depression and anxiety, including self-harm and suicide.
7. Conclusion: Social Media Is a Major Cause of Mental Illness in Girls, Not Just a Tiny Correlate
We are now 11 years into the largest epidemic of teen mental illness on record. As the CDC’s recent report showed, most girls are suffering, and nearly a third have seriously considered suicide. Why is this happening, and why did it start so suddenly around 2012?
It’s not because of the Global Financial Crisis. Why would that hit younger teen girls hardest? Why would teen mental illness rise throughout the 2010s as the American economy got better and better? Why did a measure of loneliness at school go up around the world only after 2012, as the global economy got better and better? (See Twenge et al. 2021). And why would the epidemic hit Canadian girls just as hard when Canada didn’t have much of a crisis?
It’s not because of the 9/11 attacks, wars in the middle east, or school shootings. As Emile Durkheim showed long ago, people in Western societies don’t kill themselves because of wars or collective threats; they kill themselves when they feel isolated and alone. Also, why would American tragedies cause the epidemic to start at the same time among Canadian and British girls?
There is one giant, obvious, international, and gendered cause: Social media. Instagram was founded in 2010. The iPhone 4 was released then too—the first smartphone with a front-facing camera. In 2012 Facebook bought Instagram, and that’s the year that its user base exploded. By 2015, it was becoming normal for 12-year-old girls to spend hours each day taking selfies, editing selfies, and posting them for friends, enemies, and strangers to comment on, while also spending hours each day scrolling through photos of other girls and fabulously wealthy female celebrities with (seemingly) vastly superior bodies and lives. The hours girls spent each day on Instagram were taken from sleep, exercise, and time with friends and family. What did we think would happen to them?
The Collaborative Review doc that Jean Twenge, Zach Rausch and I have put together collects more than a hundred correlational, longitudinal, and experimental studies, on both sides of the question. Taken as a whole, it shows strong and clear evidence of causation, not just correlation. There are surely other contributing causes, but the Collaborative Review doc points strongly to this conclusion: Social Media is a Major Cause of the Mental Illness Epidemic in Teen Girls.
Image: Percent of UK adolescents with “clinically relevant depressive symptoms” by hours per weekday of social media use, including controls. Haidt and Twenge created this graph from the data given in Table 2 of Kelly, Zilanawala, Booker, & Sacker (2019), page 6.
