Nov. 18, 2003 -- One concussion puts athletes at great risk for future concussions, a new study shows. In fact, even mild head injuries -- such as a simple ding -- require a week or more for recovery.
That's the message from two studies appearing in this week's Journal of the American Medical Association, both sponsored by the National College Athletic Association.
The studies are part of a sea of change in sports medicine. For years, doctors have downplayed both minor and severe head injuries if there is no loss of consciousness, significant amnesia, or other obvious brain-related changes.
However, animal studies have shown that the brain may need from days to weeks to fully recover from a concussion.
Vulnerability to Future Concussions
Athletes with a history of a concussion are at greater risks for future concussion than those without a history of head injuries, writes researcher Kevin M. Guskiewicz, PhD, with the Injury Prevention Research Center at the University of North Carolina at Chapel Hill.
In fact the study finds that those with a history of multiple concussions also have a greater likelihood of having concussion within the same season.
In his study, Guskiewicz and colleagues tracked concussions involving 2,905 football players at 25 U.S. colleges during three football seasons. They found that 6% of players had a concussion, and that 7% of those players had another head injury within the same season.
- Players with a history of three or more previous concussions were three times more likely to have a concussion within the season than those without a history of a concussion.
- Headache was the most commonly reported symptom of concussion at the time of head injury; generally, the headache lasted about 82 hours. Other symptoms included dizziness, problems with balance, and slower thinking.
- Those who had multiple concussions had slower recovery time; 30% of those with more than three previous head injuries had symptoms more than one week; 15% of those with just one previous concussion took a week to recover.
- Of the 12 within-season repeat concussions, 92% occurred within 10 days of the first injury, and 75% occurred within seven days of the first injury.
Recovery of brain function may be slower for those with previous head injuries, Guskiewicz explains.
The researchers write that given their findings of a threefold higher risk of future concussion, athletes should be better informed about the risks of injuries.
Recovery Varies Among Players
In his study, Michael McCrea, a neuroscience researcher at Waukesha Memorial Hospital in Wisconsin, tracked 1,631 football players from 15 U.S. colleges during three seasons. Of these, 94 players with concussion and 56 noninjured players were studied. All of these athletes underwent baseline assessments of symptoms, balance, and tests of attention, concentration, memory, and processing speed immediately after the injury and during the follow-up period.
- Injured football players required several days to recover from even the mildest head injuries.
- Injured athletes had more severe symptoms such as slowness in thinking and balance problems immediately after concussion, gradually recovering within one week after the head injury. There was no evidence of problems 90 days after the accident.
- Recovery varied from player to player, on average symptoms resolved within seven days -- with 10% requiring more than a week to fully recover.
This suggests that doctors cannot necessarily expect that all football players will completely recover from head injuries in one week, writes McCrea. Studying the course of recovery is critical in determining the interval in which the injured brain may be most vulnerable, writes McCrea. The study provides evidence-based guidelines for safe return to play of athletes after a brain injury.