data suggest.
In a multicenter study of almost 900 children with concussion or orthopedic injury, differences between groups in full-scale IQ (Cohen’s d = 0.13) and matrix reasoning scores (d = 0.16) were small.
“We draw the inference that IQ scores are unchanged, in the sense that they’re not different from [those of] kids with other types of injuries that don’t involve the brain,” said study author Keith Owen Yeates, PhD, Ronald and Irene Ward Chair in Pediatric Brain Injury and a professor of psychology at the University of Calgary (Alta.).
The study was published in Pediatrics.
A representative sample
The investigators analyzed data from two prospective cohort studies of children who were treated for concussion or mild orthopedic injury at two hospitals in the United States and five in Canada. Participants were aged 8-17 years and were recruited within 24 hours of the index event. Patients in the United States completed IQ and performance validity testing at 3-18 days after injury. Patients in Canada did so at 3 months after injury. The study used the short-form IQ test. The investigators included 866 children in their analysis.
Using linear modeling, Bayesian analysis, and multigroup factor analysis, the researchers found “very small group differences” in full-scale IQ scores between the two groups. Mean IQ was 104.95 for the concussion group and 106.08 for the orthopedic-injury group. Matrix reasoning scores were 52.28 and 53.81 for the concussion and orthopedic-injury groups, respectively.
Vocabulary scores did not differ between the two groups (53.25 for the concussion group and 53.27 for the orthopedic-injury group).
The study population is “pretty representative” from a demographic perspective, although it was predominantly White, said Dr. Yeates. “On the other hand, we did look at socioeconomic status, and that didn’t seem to alter the findings at all.”
The sample size is one of the study’s strengths, said Dr. Yeates. “Having 866 kids is far larger, I think, than just about any other study out there.” Drawing from seven children’s hospitals in North America is another strength. “Previous studies, in addition to having smaller samples, were from a single site and often recruited from a clinic population, not a representative group for a general population of kids with concussion.”
The findings must be interpreted precisely, however. “We don’t have actual preinjury data, so the more precise way of describing the findings is to say they’re not different from kids who are very similar to them demographically, have the same risk factors for injuries, and had a similar experience of a traumatic injury,” said Dr. Yeates. “The IQ scores for both groups are smack dab in the average range.”
Overall, the results are encouraging. “There’s been a lot of bad news in the media and in the science about concussion that worries patients, so it’s nice to be able to provide a little bit of balance,” said Dr. Yeates. “The message I give parents is that most kids recover within 2-4 weeks, and we’re much better now at predicting who’s going to [recover] and who isn’t, and that helps, too, so that we can focus our intervention on kids who are most at risk.”
Some children will have persisting symptoms, but evidence-based treatments are lacking. “I think that’ll be a really important direction for the future,” said Dr. Yeates.