Journalists drop the ball on big concussion/CTE story

A study about concussions and the risk of chronic traumatic encephalopathy (CTE) is generating national headlines:

USA Today: New Boston University study links repetitive hits to head, not concussions, to CTE

Washington Post: A new study shows that hits to the head, not concussions, cause CTE 

TIME: Repeated Hits to the Head — Not Concussions — May Cause CTE

The takeaway seems to be that concussions aren’t the main driver of CTE, the degenerative brain disease increasingly documented in deceased NFL football players and others who’ve suffered repeated blows to the head. Instead, all it may take is a series of minor impacts, even ones that aren’t significant enough to cause symptoms of concussion.

It’s a big story if true. But where did the results come from?

USA Today gives us details on the Boston University-led research:

The study, published in the journal Brain, used two methods to come up with its findings: A postmortem examination of four teenaged brains and a study of mice that showed instant changes to the brain after trauma — even without telltale concussion symptoms.

Qualifying the evidence

Let’s start with the obvious: Four teenaged brains and some mice can’t support sweeping conclusions about the causes of CTE.

Mice are not people, and observations about a handful of brains are incapable of showing cause and effect.

This doesn’t mean the researchers don’t have an important point to make.

It’s “an important study that presents a new hypothesis which, if true, would have implications for public health,” said Steven Atlas, MD, MPH, a primary care physician and associate professor of medicine at Harvard Medical School who is a contributor to HealthNewsReview.org.

“They’re challenging the concept that CTE is only related to severe head trauma,” he said. “They’re saying that there may be other mechanisms through which this can happen — that lesser head trauma, especially if sustained over a longer period of time, may be enough to cause this kind of damage.”

But he also said that the paper presents a hypothesis only — not conclusive evidence.

“The question is do mice prove the hypothesis?” Atlas said. “And the answer to that question is no.”

False certainty and a lack of independent perspectives

Such uncertainty was not reflected in the coverage that I saw, most of which buried caveats — if any were mentioned — at the very bottom of the story beneath a blustering headline.

Stories from HealthDay and the LA Times quoted only experts affiliated with the study and didn’t seek out alternate viewpoints.

None raised any concerns about the four teenaged brains mentioned in the story, which also are problematic for drawing conclusions about CTE.

For starters, there’s debate in the scientific community about the definition of CTE and how to diagnose it. Doctors also use different methods for diagnosing concussions.

While findings from such a tiny sample (there were also 4 control brains used for comparison) may yield clues for future research, they provide little if any firm information about whether it was concussions, repetitive sub-concussive blows, or some other factor that ultimately did or did not cause the CTE-like changes that the researchers found in these brains.

Headline claims based on mouse data

Yet most news outlets reporting on this story — including CNN’s health desk, whose piece was headlined, “It’s not concussions that cause CTE. It’s repeated hits, a study finds” — didn’t reflect this nuance.

Perhaps they relied too heavily on the framing of a University of Oxford news release about the study headlined, “Blows not concussion cause brain disease, according to new research.”

The news release talks extensively about the damage inflicted by football tackles, and how those impacts can lead to CTE even in the absence of concussions. “The [researchers’] most recent study compared injuries caused by blast waves and blows to the head in the sports field,” the release states.

In the sports field?

It’s only in the seventh paragraph of the release that we learn it was mice who were out on the researchers’ gridiron — not human football players.

In fact, it was mice studied in a laboratory who provide the primary basis for the headline claims in the news release and subsequent stories. It seems that some of those mice, when subjected to head impacts, went on to display symptoms of CTE-like impairment despite never showing signs of concussion.

It’s an interesting and potentially important result, but light years from what happens inside a human brain on a football field.

What’s the harm?

Atlas told me that “part of science is generating new hypotheses” and that he wasn’t surprised to see the researchers on this study “running with it as far as they can.”

But it’s the journalist’s job to rein in that enthusiasm and bring balance to the discussion — something that didn’t occur with most of the stories that I looked at.

It’s worth noting, as we’ve explained before, that news stories hyping concussion research may have unintended consequences.

Parents now might think that minor blows are going to cause a horrible brain disease. They might wonder whether their kids should participate in sports—or outright forbid them from playing contact sports–at a time when many kids are sedentary and obesity is common.