Recently, an editor sent me a study to cover on concussions in teenagers. At least, that’s what we thought the research was about, based on the title of its press release: “Teenagers who have had a concussion also have higher rates of suicide attempts.”
And I was excited to cover the study. Like gut bacteria and anything to do with chocolate or coffee or stem cells, concussion is a hot topic right now. That’s partly because brain scientists are just beginning to understand the lasting impacts of these sometimes subtle but probably cumulative injuries.
And they affect everybody from pro athletes to pee wee football players. So when parents and coaches see the word “concussion,” their thoughts rightfully turn to young athletes. About half of concussions in kids ages 8 to 19 are sports-related, according to a nationwide study of concussions published in 2010 in the journal Pediatrics.
The press release said the study found that kids who have had concussions were not only more likely to try to commit suicide, but to engage in other sorts of high-risk behaviors like taking drugs, stealing cars, setting fires and bullying.
The message here is that a kid who gets hit in the head too many times – presumably playing sports – might turn to drug abuse, self-injury and other sorts of criminal behaviors. And that’s the way it was covered in the press.
Turns out, though, the research wasn’t exactly about concussions. In fact, the word “concussion” isn’t used once in the entire study text, which was published in the journal PLoS One.
So that was my first question to Gabriela Ilie, the lead author of the study and a post-doctoral fellow at St. Michael’s Hospital in Toronto, Canada.
Here’s how our conversation went:
Me: I was a little surprised when I read your study because it sounds so different from the press release. Did you have a hand in the press release at all?
Ilie: I did look at it.
Me: I noticed that the word “concussion” wasn’t used in your study at all, and yet the press release makes it sound like the study was about concussions. Are you pretty sure that most of these traumatic brain injuries [counted in the study] are concussions?
Ilie: No, I think they are a little more than concussions. Our definition of traumatic brain injury was one in which one loses consciousness for at least five minutes or is hospitalized overnight due to symptoms associated with it for at least one night. So that’s a little more than a concussion … I felt tempted to edit that.
Ultimately, she said she didn’t because he realized that the writer of the press release was trying to use a term most people could understand.
But she should have tweaked the language. Here’s why:
By one estimate, less than 10 percent of concussions involve a loss of consciousness. In a concussion, a blow to the head or a violent shaking causes a temporary loss of brain function, so that patients may feel confused, dizzy, throw up or otherwise seem to be out of it. But they don’t usually black out.
So if they were only counting incidents that involved a loss of consciousness, the bulk of injuries reported were probably in a bit different and more serious category, according to my independent expert Sara Chrisman, M.D., M.P.H., a pediatrician at Seattle Children’s Hospital.
“It all falls under the definition of mild traumatic brain injury, but what they’re looking at is more severe subset of that,” Chrisman said. “And to me, it’s problematic because it means that most likely the reason that you have that injury is a car accident or potentially assault, or something besides a sports-related concussion, so that’s very different,” she added.
Indeed, car accidents are the major cause of mild traumatic brain injuries in teens, not sports.
“The population of kids that are in motor vehicle accidents tends to have a parent who was more likely to be drinking or to have other risk factors that could be themselves risk factors for depression,” Chrisman said.
So confounding is likely to be an issue in this study.
But there’s another, and perhaps more important problem with the press release. The study was observational (so correlation, not causation) and cross-sectional, so it’s a snapshot in time. Researchers asked nearly 5,000 students in grades 7 through 12 whether they had ever had a head injury. They also asked about risky behaviors and suicide attempts. Importantly, though, they can’t tell, based on the data they collected, which came first – the risky behavior or the traumatic brain injury (TBI).
From the study’s discussion:
An important limitation is the lack of information about the temporal relationship between the report of lifetime TBI and the co-occurring adverse correlates identified here. It is not possible, in these data to establish whether these adverse correlates represent a coping mechanism to deal with the effects of TBI, or predisposing factors for adolescent TBI, or both.
(There’s a reason why Ivan Oransky, M.D., AHCJ’s vice president and global editorial director for MedPage Today, calls it “journalistic malpractice” to cover a study without a copy of the study in front of you.)
When you have a chicken-and-egg association, as happens in cross-sectional studies, I find it useful sometimes, for perspective, to just flip the relationship. So the press release could just have easily have read, “Kids with risky behaviors also prone to head injuries.”
But that’s a headline that would have gotten a lot less attention, isn’t it? It’s less surprising, less sexy, and, until researchers better understand the nature of the relationship, there’s really not much of a take-home message here.
Reporters, however, should be left with plenty to ponder about the limits of studies and the pitfalls of following an overreaching press release.