Overall, this latest study adds to a growing body of literature that shows girls have a higher incidence of concussions than boys and might also experience more persistent symptoms, says Robert Cantu, a neurosurgeon and professor at Boston University who did not take part in the new research. “This is one of the most robust studies in terms of the numbers of people involved,” he says, confirming “girls take longer to recover.”

Yet some concussion experts caution this latest work has some limitations. Mayumi Prins, who studies traumatic brain injury in children at the University of California, Los Angeles,  points out that whereas Neidecker’s findings are consistent with what others have reported, a key consideration is that the authors relied on the athletes’ self-reports to determine their conditions at baseline (before the injury happened)—measures physicians typically use to determine whether a concussion has resolved. “Self-reporting or parental-reporting is often fraught with errors,” Prins says.

More generally, there is also evidence of gender differences in symptom-reporting across concussion studies. For example, a study published earlier this year in the Journal of Athletic Training found that although high-schoolers of both sexes were equally knowledgeable about concussion symptoms, girls were more likely to disclose sports-related injuries to authority figures such as a medical professional or coach.

Ultimately, Prins says, researchers need an objective test to determine whether an individual has had a concussion. Scientists are currently working on developing better neuroimaging measures and identifying biomarkers in blood and other bodily fluids. In the meantime, however, one thing does appear to be clear: Concussion risk factors—and how they may differ by sex—require further scrutiny. Understanding what preinjury conditions are associated with recovery has important implications for treatment, Collins says. “The bottom line here is the injury needs to be recognized, the patient needs to be taken out of play and the [concussed] kids need to go to the clinics where they can get the multidisciplinary care that they need.”