Antonio Guillem/Shutterstock
Source: Antonio Guillem/Shutterstock

Self-harm among 10- to 14-year-old girls in the U.S. has nearly tripled since 2009, according to a Centers for Disease Control analysis of emergency department admissions, just published in the Journal of the American Medical Association.

American girls, some as young as 4th graders, are now nearly three times more likely to harm themselves via cutting, poisoning, and other methods severe enough to send them to the ER. This follows a British study from last month finding a 68 percent increase in self-harm among 13- to 16-year-old girls in the UK between 2011 and 2014.

It is heartbreaking to think about the pain these girls must be in and the pain their parents must feel witnessing it.

Older teen girls and women were not immune: Self-harm increased 63 percent among 15- to 19-year-old girls and women, and 22 percent among 20- to 24-year-old women in the U.S. Self-harm among boys and men is much less common; only about 10 percent of the rate of girls. (The CDC research found increases in rates of self-harm over this period for boys as well, but they weren’t statistically significant.)

These findings join a sad litany of evidence for increases in mental health issues among teens since 2010, primarily among girls, including in depressive symptoms and clinical-level depression. Some have wondered if these increases have occurred because today’s teens are more comfortable admitting to their problems. That’s unlikely, given the lengths to which the survey administrators go to ensure anonymity and the large, sudden increases in depression. (A greater willingness to admit to problems would be more likely to have appeared gradually and to have begun in the 1990s, when mental health issues began to be more widely discussed.)

These data on self-harm should be the end of the argument about willingness to admit to problems on surveys: Self-harm is a behavior, with cases documented by hospitals. Suicide, another tragic behavior, has also increased among teens in a very similar pattern, also with larger increases for girls. This alarming rise in mental health issues among teens can’t be explained away by methodological concerns, given the consistency of the evidence from both surveys and behaviors.

But why?

It is crucially important that we figure out why this is happening. Below, I’ll offer my perspective as a cultural change researcher and author of a book on this generation (iGen).

Following are the five causes mentioned most frequently for the rise in mental health issues among teens — and why, in my view, they do or don’t fit the data. The question here is not "What are all the possible causes of self-harm?" The question is "What possible causes of self-harm also changed from 2009 to 2015, and thus could explain the increase?"

1. The Great Recession and cyclical economic factors.

These increases in self-harm begin in 2010, more than two years after the Great Recession officially began in December 2007. If the Great Recession were the cause of the increase in self-harm, you’d expect the rates of self-harm to increase between 2008 and 2011, and then decline as the economy improved between 2011 and 2015. However, self-harm was higher in 2015 (when the economy was doing very well) than it was in 2009 and 2010 (when job losses and unemployment were the highest). Even if the recession had lingering effects, you still wouldn't expect the rates to keep rising that long after the recovery.

2. Income inequality, job precariousness, and other noncyclical economic factors.

Income inequality has been increasing since the 1970s. Job precariousness (jobs becoming more unstable) followed roughly the same trajectory. If concerns about jobs were the primary driver of the increase in self-harm, you’d expect the increase to be largest among young adults (ages 20 to 24), those most likely to be looking for jobs. Instead, the increase in self-harm is the largest among 10- to 14-year-olds, the age group least likely to work. Few 10- to 14-year-olds are aware of the vagaries of the adult job market, and even if their parents tell them about it, it’s likely to sink in about as much as the rest of adult news (which is: not much). Kids this age are primarily thinking about school and about what’s going on with their friends.

3. More homework, and more extracurricular activities.

In the analyses for my book, I found that iGen teens actually do fewer hours of homework than teens did in the 1980s, and the decline is largest among 8th graders, the age group with the largest increase in self-harm. Time spent on extracurricular activities is stable. Plus, as we found in a paper in Clinical Psychological Science, teens who spend more time on homework are actually less likely to be depressed, as are those who spend a lot of time on sports

4. More drug and alcohol abuse.

Actually, iGen teens drink alcohol much less than past generations of teens did, with the largest declines among the youngest teens. They also go out less and party less. Teens' use of marijuana has been stable over this time period; use of other illicit drugs, including narcoticsreached all-time lows among 12th graders in recent years. Thus, substance abuse has actually declined overall among teens in the U.S. during the time self-harm increased, making it unlikely to be the cause.

5. Smartphones and social media.

The first smartphone was introduced in June 2007. According to the Pew Research Center, smartphone ownership among U.S. teens rose from 37 percent in 2011 to 73 percent in 2015. By 2016, the average child in the U.S. got her first smartphone when she was 10

In iGen, I found that between 2009 and 2015, social media went from an activity about 50 percent of teens did every day to an activity about 82 percent of teens did every day. Teens who spend more time on electronic devices have more suicide risk factors, and studies using longitudinal and experimental designs show that the causation primarily goes from social media to unhappiness rather than from unhappiness to social media use. Given the greater emotional vulnerability of younger kids and teens, you’d also expect the effects of social media and screen time to be largest in the younger groups, and that is where the self-harm increase is the largest. Thus, smartphone ownership and screen time rise at the same time as self-harm and are linked to the mental health issues that often co-occur with self-harm. It’s impossible to definitively prove that screen time — or any factor — is the cause of the rise in self-harm, but screen time cannot be ruled out as easily as the four other causes.

There's another reason to suspect smartphones: Increasing screen time was the largest change in teens' lives between 2011 and 2015. It’s not just that teens are spending more time on their phones and other devices — it’s that they are spending so much time (six to nine hours according to many estimates) that it leaves less time for other things that are beneficial for mental health, such as sleep and seeing friends in person. Screen time is a triple threat.

With that said, we should consider all of the options. Do you think there are possibilities for the increase in self-harm other than these five above? If so, chime in.

Why girls?

Why was the increase in self-harm so much larger for girls than boys? After all, boys got smartphones at the same time. Screen time, particularly social media use, may have different effects on the emotional health of girls than on boys. In the Clinical Psychological Science study, we found that social media use was significantly correlated with depression for girls, but not for boys. Developmentally, girls are more concerned with physical appearance and social popularity than boys are. Social media is a showcase of those issues, even quantifying them in numbers of likes and followers. Girls also spend more time on social media than boys do; boys instead spend more of their screen time playing games, often with friends present, either physically or virtually.

Of course, we need much more research on this question. We need to find out more about how girls are feeling when they are on their phones and/or on social media. Anecdotal reports suggest that the answer is, in short: Not good.

Self-harm and depression have many causes, including genetic predisposition, trauma, and poverty. But with self-harm tripling among girls over a six-year period, there must be additional important causes at the cultural level, which are having a large impact on the lives of teen girls. It is imperative that we identify these causes and take action.

Screen time is at least a place to start, perhaps with reasonable limits such as putting off buying smartphones for kids until they are emotionally ready and, when they get one, making sure their use stays under about two hours a day (at which point, research suggests, the risks of mental health issues start to increase). This type of intervention has few downsides. In contrast, the downside of doing nothing is considerably greater. 

References

Twenge, J. M., Joiner, T. E., Rogers, M. L., & Martin, G. N. (in press). Increases in depressive symptoms, suicide-related outcomes, and suicide rates among U.S. adolescents after 2010 and links to increased new media screen time. Clinical Psychological Science.

Mercado, M. C., Holland, K., Leemis, R. W., Stone, D. M., & Wang, J. (in press). Trends in emergency department visits for nonfatal self-inflicted injuries among youth aged 10 to 24 years in the United States, 2001-2015. Journal of the American Medical Association.

Mojtabai, R., Olfson, M., & Han, B. (2016). National trends in the prevalence and treatment of depression in adolescents and young adults. Pediatrics, 138(6).

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