The toll from gun violence at schools has only escalated in the 20 years since the jolting, horrific massacre at Columbine High.

By December 2019, at least 245 primary and secondary schools in the United States had experienced a shooting, killing 146 people and injuring 310, according to The Washington Post.

At least 245 primary and secondary schools in the United States have experienced a shooting — killing 146 people and injuring 310 — since the country's first mass school shooting at Columbine High School in April 1999.

Now, new Stanford-led research sounds an alarm to what was once a silent reckoning: the mental health impact to tens of thousands of surviving students who were attending schools where gunshots rang out.

A study has found that local exposure to fatal school shootings increased antidepressant use among youths.

Specifically, the average rate of antidepressant use among youths under age 20 rose by 21 percent in the local communities where fatal school shootings occurred, according to the study. And the rate increase – based on comparisons two years before the incident and two years after – persisted even in the third year out.

“There are articles that suggest school shootings are the new norm – they’re happening so frequently that we’re getting desensitized to them – and that maybe for the people who survive, they just go back to normal life because this is just life in America. But what our study shows is that does not appear to be the case,” said Maya Rossin-Slater, a core faculty member at Stanford Health Policy and faculty fellow at the Stanford Institute for Economic Policy Research (SIEPR). “There are real consequences on an important marker of mental health.”

The study is detailed in a working paper published Monday by the National Bureau of Economic Research. It was co-authored by Rossin-Slater, an assistant professor of health policy in the Stanford School of Medicine; Molly Schnell, a former postdoctoral fellow at SIEPR now an assistant professor at Northwestern University; Hannes Schwandt, an assistant professor at Northwestern and former visiting fellow at SIEPR; Sam Trejo, a Stanford doctoral candidate in economics and education; and Lindsey Uniat, a former predoctoral research fellow at SIEPR now a PhD student at Yale University.

Their collaborative research – accelerated by their simultaneous stints at SIEPR – is the largest study to date on the effects of school shootings on youth mental health.

The study comes as the issue of gun safety continues to stoke political wrangling and public debate. And the researchers say their findings suggest policymakers should take a wide lens to their decision-making process.

“When we think about the cost of school shootings, they’re often quantified in terms of the cost to the individuals who die or are injured, and their families,” Rossin-Slater noted. “Those costs are unfathomable and undeniable. But the reality is that there are many more students exposed to school shootings who survive. And the broad implication is to think about the cost not just to the direct victims but to those who are indirectly affected.”

A Driver for Antidepressant Use

More than 240,000 students have been exposed to school shootings in America since the mass shooting in Columbine in April 1999, according to The Washington Post  data used in the study. And the number of school shootings per year has been trending up since 2015.

Yet despite this “uniquely American phenomenon” – since 2009, over 50 times more school shootings have occurred in the U.S. than in Canada, Japan, Germany, Italy, France and the United Kingdom combined – little is known about the effects of such gun violence on the mental health of the nation’s youth, the study stated.

“We know that poor mental health in childhood can have negative consequences throughout life,” Schwandt said. “At the same time, children are known to show significant levels of resilience, so it really wasn’t clear what we would find as we started this project.”

The researchers examined 44 shootings at schools across the country between January 2008 and April 2013. They used a database that covered the near universe of prescriptions filled at U.S. retail pharmacies along with information on the address of the medical provider who prescribed each drug. They compared the antidepressant prescription rates of providers practicing in areas within a 5-mile radius of a school shooting to those practicing in areas 10-to-15 miles away, looking at two years prior and two to three years after the incident.

Of those 44 school shootings, 15 of them involved at least one death. The 44 shootings occurred in 10 states: Alabama, California, Connecticut, Florida, Nebraska, North Carolina, Ohio, South Carolina, Tennessee and Texas.

Researchers found a marked increase in the rate of antidepressant prescriptions for youths nearby, but only for the shootings that were fatal. They did not see a significant effect on prescriptions for youths exposed to non-fatal school shootings.

“The immediate impact on antidepressant use that we find, and its remarkable persistence over two, and even three years, certainly constitutes a stronger effect pattern than what we would have expected,” Schwandt said.

Meanwhile, adult antidepressant use did not appear to be significantly impacted by local exposure to school shootings.

Layers of Costs, More Unknowns

The researchers also analyzed whether the concentration of child mental health providers in areas affected by fatal school shootings made a difference in the antidepressant rates, and they drilled a further comparison between the prevalence of those who can prescribe drugs, such as psychiatrists and other medical doctors, and those who cannot prescribe drugs, such as psychologists and licensed social workers.

Increases in antidepressant rates were the same across areas with both high and low concentrations of prescribing doctors, the researchers found. But in areas with higher concentrations of non-prescribing mental health providers, the increases in antidepressant use were significantly smaller – indicating perhaps a greater reliance on non-pharmacological treatments or therapy for shooting-related trauma.

The researchers also found no evidence that the rise in antidepressant usage stemmed from mental health conditions that were previously undiagnosed prior to the shootings.

In totality, the researchers say the results in the study clearly pointed to an adverse impact from a fatal shooting on the mental health of youths in the local community. Furthermore, the results capture only a portion of the mental health consequences: Non-drug related treatments could have been undertaken as well.

“Increased incidence of poor mental health is at least part of the story,” Schnell said.

Though their analysis included only 44 schools and 15 fatal school shootings, Rossin-Slater noted how the trend of school shootings is growing. She believes the mental health impact found on the local communities they studied “can be generalizable to other communities’ experiences.”

That’s all the more reason why policymakers should consider the overall negative effects of school shootings, and how further research will be needed to gauge other societal consequences, the researchers said.

“Think of it as layers of costs,” Rossin-Slater said. And when it comes to evaluating gun violence at schools, “we think our numbers say, ‘Hey, these are costly things, and it’s costlier than we previously thought.’”

Americans have witnessed repeated mass shootings. The carnage in Texas and Ohio last weekend claimed another 31 lives and has left the nation stunned and angry.

Many are demanding that members of Congress pass tougher gun-control laws; others blame mental health and violent video games for the rampant shootings.

Stanford Health Policy’s David Studdert — an expert on the public health epidemic of firearms violence — acknowledges that mass shootings are on the rise in the United States.

“It’s been a horrific weekend,” said Studdert, a professor of law at Stanford Law School and professor of medicine at Stanford School of Medicine. “Experts now generally agree that mass shootings are becoming more common — and that a common thread is disaffected young men who have access to high-caliber, high-capacity weapons.”

Both suspects in the Dayton and El Paso shootings fit this profile.

Studdert notes, however, that while mass shootings have become the public face of gun violence, they account for less than 1% of the 40,000 firearm deaths each year.

“So as a public health researcher, I do care about mass shootings and I am interested in understanding and their causes — but the focus of my ongoing research is the other 99 percent.”

Largest investment in firearms research in two decades

It’s that focus the Studdert will be pursuing in a recently-awarded $668,000 grant from the National Collaboration on Gun Violence Research. The private collaborative’s mission is to fund nonpartisan, scientific research that offers the public and policymakers a factual basis for developing fair and effective gun policies.

Studdert, Yifan Zhang, a statistician with Stanford Health Policy, and Stanford political scientist Jonathan Rodden are working with colleagues at UC Davis, Northeastern University and Erasmus University Rotterdam on the Study of Handgun Ownership and Transfer, or LongSHOT.

The team is following several million Californians over a 12-year period to better understand the causal relationship between firearm ownership and mortality. They launched in 2016 with the initial goal of assessing the risks and benefits of ownership for firearm owners.

“The implications of firearm ownership for owners is important because they usually are the ones making the decision to purchase and own,” Studdert said. “But we knew from the beginning that this was only part of the picture. The presence of a firearm in the home may also have health implications for the owners’ family members.”

In the new study, the researchers will identify the cohort of adults in California who live with firearm owners but are not themselves gun owners, and then compare their risks of mortality to a group who neither own weapons, nor live with others who do.

Surprisingly little is known about the “secondhand” effects of having guns in the home.

“Existing studies don’t differentiate between owners and non-owners within households, and that is something we have the ability to look at,” Studdert said. “And a very large proportion of non-gun-owners who are living in homes with guns are women — so this is a group that has really been understudied.”

There is already substantial evidence that a gun in the home is associated with increased risks of suicide. But it is not clear how particular subgroups, such as women who don’t own guns, are affected.

“Because our cohort is so large,” Studdert said, “we will also be able to explore whether gun ownership confers certain benefits, as gun-rights advocates often claim, such as enhanced safety in dangerous neighborhoods.”

Studdert said a better accounting of the risks and benefits that firearm ownership poses for non-owners could help inform decisions regarding gun ownership and storage, as well as policies aimed at improving gun safety.

The politics of federal funding for firearms research

The National Collaboration on Gun Violence Research is funded through private philanthropic donations. It was seeded with a $20 million gift from Arnold Ventures and intends to raise another $30 million in private funding for firearms research.

“It’s the biggest investment in firearms research since the late 1990s,” Studdert said.

Research on the impact and causes of firearm violence was dealt a huge blow in 1996 when the so-called Dickey Amendment was passed by Congress. The law has been interpreted as prohibiting the National Institutes of Health and the Centers for Disease Control and Prevention from conducting firearms research.

Studdert said that the growth of research funding from philanthropies like the Arnold Foundation and Joyce Foundation is a welcome development, but that it will take a large and sustained investment to move the science of firearm violence forward.  

“The core funder of large-scale research essentially vacated the space for 20 years,” he said.  “It’s going to take some time to recover. Developing a generation of researchers with expertise will take give to 10 years. But it has to be done — the size of the social problem demands it.”