(RxWiki News) Getting a head injury is a risk that comes with playing football. A disproportionate number of athletes in that contact sport have had a concussion, a brain injury that has been increasingly in the spotlight.
A recent study found that college football players who had been diagnosed with a concussion or who had been playing a relatively long time, had a smaller hippocampus than football players with no history of concussions and non-players who never had a concussion.
The hippocampus has a major role in controlling emotions and keeping the memory sharp.
This study also showed that players with concussions and more years of play experience had slower reaction times.
"Stay off the playing field to recover from a concussion."
Rashmi Singh, PhD, of the Laureate Institute for Brain Research in Tulsa, OK, was this study’s lead author.
Dr. Singh and his research team enrolled 25 college football players with a history of being medically diagnosed with concussion, 25 football players without a history of concussion, and 25 persons who did not play football and never had a concussion. The study ran from June 2011 through August 2013.
High-resolution magnetic resonance imaging (MRI) was conducted to show the size of study participants’ brains. In addition, the athletes were given a computerized test of their memory and other cognitive skills that concussion can effect.
The researchers found that players with and without a history of concussions had a smaller hippocampus that the non-athletes. In addition, players who had been diagnosed with concussion had a smaller hippocampus than players who had not been diagnosed with concussion.
Also, in both groups of football payers, the part of the hippocampus that is on the left side of the brain got smaller the longer these players were involved in their sport. That change was “statistically significant,” the researchers wrote. There was no significant change in the right hippocampus based on years of play.
Signals created in the left hippocampus that have been associated with learning and memory are not created by the right hippocampus.
The left hippocampus of the players who had been diagnosed with concussion was 23.8 percent smaller, on average, than the left hippocampus of non-athletes. The left hippocampus of players who had not been diagnosed with concussion was 14.1 percent smaller than that of non-athletes.
The right hippocampus of players with a history of concussions was 25.6 percent smaller than that of the non-players. The right hippocampus of players with no history of concussions was 16.7 percent smaller than that of non-players.
The players self-reported the number of years they had played football.
While both groups of football players performed equally on cognitive tests of their memory and other behaviors, players diagnosed with concussions had slower reaction times than players with no history of concussion.
Because the hippocampus can be affected by such factors as genetics, life-long brain development, personal growth patterns and hormones, these researchers said there needs to be more scientific investigation on these differences in hippocampus size among athletes.
Production of stress hormones, they added, have been linked to hippocampus size. Many athletes experience a great deal of physical and psychological stress, the researchers wrote.
This study was published online May 13 JAMA.
The Laureate Institute for Brain Research, whose work is financed by the William K. Warren Foundation, funded this study.
These researchers reported that they had no financial investments or ethical conflicts that would shape study design, outcomes and analysis.