In the wake of school shootings, mental health is often thrust into the spotlight. After a young gunman killed children and staff at Sandy Hook Elementary School in Connecticut in 2012, for example, the state enacted laws requiring the tracking of voluntary commitments to psychiatric hospitals, upped state services for the mentally ill and required school districts to increase mental health trainings.

Such efforts may help prevent mass shootings, but new research highlights a challenge in preventing school violence: Other behavioral factors, such as alcohol and drug use, may actually be more closely linked to youth gun possession than mental health is.

"While mental health is one component, there are multiple other factors that are strongly associated with gun possession," said study researcher Sonali Rajan, an assistant professor of health education at Teachers College, Columbia University in New York. [Fight, Fight, Fight: The History of Human Aggression]

Risk factors

Rajan and her study co-author, Kelly Ruggles, a research scientist in population health at the New York University School of Medicine, wanted to approach the issue of youth gun violence in a non-partisan, non-ideologically-driven way. They focused not on mass shootings alone, but on gun carrying among high-school-age teens. About 3,000 youth under age 18 are killed by guns each year, according to research by Children's Defense Fund. Though mass shootings are devastating, they account for only a handful of these deaths.

The researchers used data on 13,500 to 16,500 high school students collected yearly between 2001 and 2011 by the Centers for Disease Control and Prevention (CDC). In surveys, the kids reported whether they had engaged in a number of behaviors that researchers consider risky to health. The researchers then used a method of statistical analysis more commonly used in gene expression studies to look at how certain risky behaviors may cluster together. They also compared each risk factor to each other risk factor, to see which tended to go hand-in-hand.

The researchers found that the behaviors most strongly associated with gun possession were using alcohol, using tobacco and using other drugs, Ruggles and Rajan reported Nov. 5 in the journal PLOS ONE.

Other factors that strongly correlated with gun carrying had to do with the school environment. Teens who said they had done drugs at school, been in a fight at school or had been threatened at school were also more likely to report carrying a gun in the month before taking the questionnaire.

"The school environment seems to play a large role," Ruggles told Live Science. [5 Milestones in Gun Control History]

The researchers' method of looking at so many behaviors enabled them to avoid biases, and come at the question of which behaviors in kids are linked with carrying guns with a blank slate. "Typically, [gun violence] research is not informed by data, but often is informed by incidents in the media and inflammatory rhetoric," Rajan told Live Science.

Casting such a wide net over data can sometimes lead to spurious correlations, warned Dr. Fred Rivara, a professor of pediatrics at the University of Washington and Seattle Children's Hospital, who was not involved in the study. For that reason, Rivara told Live Science, it is often useful for studies to focus on specific risk factors rather than analyzing everything.

Nevertheless, Rivara said, the new results were in line with what would be expected from other research studies: Gun possession in youth is part of a complex stew of risky behavior.

Fixing the problem

Between 5 percent and 6 percent of students surveyed each year reported carrying a gun in the 30 days prior. Most of these students did not engage in gun violence, the researchers said, although their carrying a weapon puts them at higher risk of doing so.

"The real question is, what can we do about it?" Rivara said. The risk factors for youth violence are known, he said, but research on which programs or laws can prevent gun violence in youth is lacking.

In part, that's because of limits on some of the federally funded research on gun violence, he said. Beginning in the 1990s, Congress began amending budget appropriations with language forbidding any research that might "advocate or promote gun control." After the Sandy Hook shooting in 2012, President Barack Obama called for federal funding of gun research, prompting the National Institutes of Health (NIH) to put out a call for grant proposals. He also directed the Centers for Disease Control and Prevention (CDC) to fund gun research, but pushback from Republicans in Congress may prevent federal money from reaching researchers, according to an investigation by ProPublica.

Ruggles and Rajan completed their work without any outside funding; they say they hope to set the stage for future research that will dig into the cause-and-effect relationships between risk factors and gun use in youth. Focusing on mental health will not be enough, they said.

However, the finding that school environment is important may hint at one place that authorities can start in trying to discourage youth from mixing with guns, they said. Another study released this year found that bullied children are nearly twice as likely to carry weapons to school compared to children who are not bullied.

"Particularly in the wake of mass shootings, when there is really sensationalized violence in schools and communities, we have a tendency as community members to want to simplify the gun violence issue," Rajan said. "For example, 'Such-and-such was depressed and that's why they did this.' Gun violence is a very complex issue and one that is likely influenced by many factors that are not understood and rarely discussed."

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