Brains of Football Players Don't Fully Recover During Offseason, Study Finds
Some football players' brains may not fully recover from hits endured even after six months of no-contact rest during the offseason, suggests a new study published online today in the open-access journal PLOS ONE.
The study examined the brains of 10 Division III University of Rochester football players before the start of the 2011 season, at the end of the season, and after six months of no-contact rest (the offseason). The players, who wore football helmets equipped with accelerometers to track every hit, sustained anywhere between 431 and 1,850 head blows while taking part in daily practices and weekly games, but none of the 10 suffered a concussion.
Six months after the end of the season, imaging scans showed changes in white matter consistent with mild brain injury in about half the players, despite the fact that none of them had suffered a concussion.
These brain changes were compared to a control group of five college students who didn't play contact sports. According to the analysis, the white matter in the players' brains began to look different from the control group when players experienced as few as 10 to 15 head impacts with a rotational acceleration above a certain threshold (6,000 radians/sec2).
"I don't want to be an alarmist, but this is something to be concerned about," said Dr. Jeffrey J. Bazarian, the lead author of the study and an associate professor of Emergency Medicine at the University of Rochester School of Medicine and Dentistry, in a statement. "At this point we don't know the implications, but there is a valid concern that six months of no-contact rest may not be enough for some players. And the reality of high school, college and professional athletics is that most players don't actually rest during the off-season. They continue to train and push themselves and prepare for the next season."
The post-season white-matter changes "imply a potential causal relationship between helmet impact forces during a season of collegiate football and [white-matter] injury, despite no clinically evident concussion," the authors suggest. They also posit that the persistence of such changes could mean that student-athletes are at further risk when they return to play the next season.
Based on their findings, the authors suggest that changes in immunity could impact white-matter recovery, as levels of certain inflammatory markers found in a player's blood correlated with a lack of full white-matter recovery.
"What is an adequate rest period? We don't know. Six months may be enough for some players but not for others," Bazarian said. "The autoimmune response and inflammation we observed in the blood of players who didn't recover could be a result of genetics, diet, or other factors, but it was not the result of a concussion, since none of the athletes suffered one."
The possibility of repetitive head impacts directly causing long-lasting white-matter changes requires further research, the authors conclude, but confirming a relationship between the two could lead to advances in sports-injury research. Scientists and doctors could begin examining "modifiable factors that may influence [white-matter] recovery," they suggest, which could help reduce the long-term risk of chronic traumatic encephalopathy, or CTE.
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