An 11-year retrospective study - involving almost 160,000 high school student-athletes - shows a more than four-fold increase in concussion rates in boys' and girls' sports at 25 high schools in suburban Washington, D.C. Overseen by Andrew Lincoln, director of the Sports Medicine Research Center at Union Memorial Hospital in Baltimore, the study suggests that concussions are an increasing problem at the high school level, and that girls are at least as susceptible as boys in sports played by both genders (soccer, basketball and baseball/softball).

During the period between the academic years 1997-98 and 2007-08, 2,651 concussions were electronically recorded on a daily basis by certified athletic trainers who were on-site for games and practices. The rate of annual increase during this period was 15.5 percent. Boys' football accounted for more than half of all concussions and saw the highest incidence rate (.60 per 1,000 athlete exposures). Among girls' sports, soccer had the most concussions, as well as the second-highest overall incidence rate of the 12 sports representing either gender (.35 per 1,000 athlete exposures).

The 12 sports were football, boys' and girls' lacrosse, boys' and girls' soccer, wrestling, boys' and girls' basketball, baseball, softball, girls' field hockey and cheerleading.

Lincoln and his colleagues concluded that, although collision sports had the highest number of concussions, rising rates of concussion occurred in all 12 sports observed. Concussion was observed in girls' sports at rates similar to or higher than boys' sports.

The study "lets the conversation move forward from professional football and hockey to sports that both girls and boys play," Douglas Weibe, who studies concussions at the University of Pennsylvania in Philadelphia, and who was not part of the study, told Reuters Health. "It helps us realize that concussion is a problem with both boys and girls, and in sports that are traditionally thought of as both high impact and low impact."

Lincoln says he and his team of researchers are not surprised by the results. "Anecdotally, we heard from our team physicians and athletic trainers that concussions were becoming more prevalent in recent years," he told AB. "We suspect that this is partly from student-athletes doing a better job of recognizing symptoms of concussion and reporting them to our medical providers. We've also seen more aggressive play across all sports that may contribute to the increase, as well as athletes that are better conditioned and perform at a higher level. Greater speed and energy involved in player collisions could also contribute to higher rates of concussion that we identified."

If student-athletes are getting better at reporting their own symptoms, that's a major step in the right direction. Late last year, ESPN The Magazine reported on a survey it conducted with 300 high school football players, 100 high school football coaches, 100 certified athletic trainers and 100 parents about their attitudes toward concussions. "Everyone is doing their part, except the player," a certified athletic trainer in Illinois told the magazine. "If you are concussed, you don't play. But players won't accept that."

Lincoln notes that greater focus on concussions and their health ramifications should be made at the high school level nationwide. And to that end, at least nine states have enacted concussion laws that typically require concussion education for players, coaches and parents; immediate removal from play of a student-athlete who appears to have suffered a concussion; and clearance by a health-care professional before a concussed player returns to action. And other states - including Pennsylvania, Wyoming and Utah - have legislation pending.

"Greater efforts must be made to detect, treat and prevent concussion in all sports at the high school level," Lincoln says.