They may still be able to return to play -- after one extra month of recovery, researchers report Jan. 18 in the journal Neurology.
"Although an athlete may experience a slow or delayed recovery, there is reason to believe recovery is achievable with additional time and injury management," said study author Dr. Thomas McAllister, from Indiana University School of Medicine.
"This is an encouraging message that may help to relieve some of the discouragement that athletes can feel when trying to return to their sport. While some athletes took longer than 24 days to return to play, we found that three-quarters of them were able to return to sports if given just one more month to recover," McAllister said in a journal news release.
The study included 1,751 college varsity athletes who had concussions diagnosed by their team physician. About 63% of the athletes were men who primarily played football, soccer or basketball. The women primarily played soccer, volleyball or basketball.
Participants were evaluated multiple times: within six hours of their injury; one or two days later; after being free of symptoms; after being cleared to return to play, and at six months.
The athletes reported their symptoms daily for up to 14 days to medical staff. They then reported their symptoms weekly if they hadn't yet returned to play.
About 23% of the athletes had a slow recovery.
Typical recovery is within 14 days for symptoms to resolve or return to play within 24 days.
Of those who took longer than 24 days to return to play, 78% were able to play within 60 days of injury. About 83% were able to return to play within 90 days of their injury.
However, about 11% had not returned to play six months after injury.
The average recovery time for the slow-recovery group was 35 days after injury compared to 13 days for those who recovered more quickly.
"The results of this study provide helpful information for athletes and medical teams to consider in evaluating expectations and making difficult decisions about medical disqualification and the value of continuing in their sport," McAllister said.
These results may not apply to other types of mild brain injuries or to other age groups, the researchers cautioned.
The study was partly funded by the U.S. Department of Defense.
The U.S. Centers for Disease Control and Prevention has more on concussion.
SOURCE: Neurology, news release, Jan. 18, 2023