For all the recent attention focused on the hundreds of thousands of hits to the head teens and children take each year, the amount of solid scientific information about concussion and recovery remains surprisingly sketchy.
A new report from the Institute of Medicine and the National Research Council released Wednesday found that research evidence about youth concussions is limited and that young athletes still face a "culture of resistance" to reporting when they might have a concussion and complying with treatment plans.
Most information about the injury comes from tracking done by colleges and some high schools, and reports from a select group of emergency departments.
''The findings of our report justify concerns about sports concussions in young people," said Dr. Robert Graham, head of a national health quality program at George Washington University and chairman of the committee that produced the 306-page report. He said there are "numerous areas in which we need more and better data."
The committee said there's little solid evidence on the best way to diagnose concussion or on how head impacts affect youths in difference stages of brain development.
It recommended that the federal Centers for Disease Control and Prevention set up a national surveillance system tracking concussions in organized sports among players ages 5 to 21. It urged the National Institutes of Health and Defense Department to conduct more studies on the short- and long-term effects of youth concussion and on the injury risks of various activities.
The committee called on sports administrative groups, such as the National Collegiate Athletic Association and National Federation of High School Associations, to support more research into rules and techniques that might lower concussion risk -- and to make extra efforts to change attitudes on and off the field about the injury and the need for rest and treatment.
One recent guideline update from the American Academy of Pediatrics underscores the dearth of research.
The guideline was based not on studies, but rather expert opinion and adaptation of one concussion management program developed at the Rocky Mountain Hospital for Children in Denver.
At issue was whether someone ordered to sit out athletic competition should also take a time out from the classroom. Each concussion is different, with individualized symptoms. Not all involve a loss of consciousness; blacking out isn't considered a sign of severity.
The new guidelines suggest that with severe symptoms -- headaches, difficulty remembering, vomiting -- that don't improve, students may need to stay home from school. If symptoms are mild or tolerable -- affecting concentration or coordination -- it may be possible to go back to school, though teachers and other staff must be informed and should monitor the student, experts say.
While most young concussion victims recover in a few weeks, some symptoms may be more severe or last much longer. That may require more formal academic adjustments such as home tutoring and recorded lectures.
Several other recent studies have shown that cognitive deficits such as the ability to focus and switch tasks easily amid distractions can endure for months, and that some students can falter quickly once they resume even moderate physical exertion.
A group of 20 high school athletes who'd suffered concussions "were still significantly impaired in their executive function" compared with those in a control group free of brain injury, researchers at the University of Oregon reported earlier this year.
A second report, from the University of Pittsburgh, showed that strenuous physical activity can affect the results of cognitive testing. Nearly a quarter of athletes whose tests cleared them to play were found, after a workout of 15 to 25 minutes, to still have verbal and visual deficits.