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Years of Play and Concussions Linked to Brain Changes in College Football Players

The number of years college football players have spent playing the sport has a significant inverse relationship to the volume of a portion of their brains associated with memory, according to a study published online Tuesday in JAMA.

The study authors compared 25 healthy Division I football players from Tulsa University with a history of concussion and 25 without a history of concussion to 25 non-player subjects with no history of brain trauma to assess whether concussions were associated with long-lasting effects on the brain. They measured the volume of each student's hippocampus, which is a part of the brain associated with memory, and the subratentorial region, which contains the cerebrum.

Football players with a history of concussion had been playing for a mean of 13.08 years, while those without a concussion had been playing for a mean of 10.50 years. Fifteen of those with a history of concussion had between one to two concussions diagnosed, while the other 10 had anywhere between three to five diagnosed.

In the left hemisphere of the brain, hippocampal volume was 14.1 percent smaller for college football players with no history of concussion and 23.8 percent smaller for those with a history of concussion compared to the control group. Right hippocampal volume was 16.7 percent smaller for college football players with no history of concussion and 25.6 percent smaller for those with a history of concussion compared to the control group.

According to regression analyses the study authors ran, left hippocampal volume was significantly inversely related to years played, but not to number of prior concussions. Right hippocampal volume, meanwhile, was not significantly related to years played nor a prior history of concussions.

All study participants went through a battery of cognitive tests, and college football players either with or without a history of concussion did not fare significantly worse than the control group. However, the number of years played did have an inverse relationship to baseline reaction time for college football players.

"Other studies have evaluated the effects on older athletes, such as retired NFL players, but no one has studied 20-year-olds until now—and the results were remarkable and surprising," said Patrick Bellgowan, one of the study's authors and the director of cognitive neuroscience for the Laureate Institute of Brain Research in Tulsa, Oklahoma, in a statement. "Our next step is to assess what caused this difference in hippocampus size."

The study authors do caution against associating correlation with causation based on their results. In other words, it's yet to be determined that playing football causes these brain changes.

"The present study design limits our ability to dissociate [regard as unconnected] among the many possible factors involved in these hippocampal volume findings, but our study should serve as an impetus for future longitudinal research to investigate the neuroanatomical and cognitive changes in young contact-sport athletes. The clinical significance of the observed hippocampal size differences is unknown at this time," the authors conclude.

A study published in The Journal of Neuroscience back in December 2012 found changes in a child's brain to persist even months after suffering a concussion, even if the child is symptom-free. That study specifically referred to white matter, which is present in the hippocampus and other regions of the brain, and led the authors to conclude "developmental differences in the brain or the muscular-skeletal system may render pediatric patients more susceptible to injury."

This JAMA study appears to only add fuel to that fire, given the long-lasting changes discovered in the brains of collegiate football players. Though the players did not perform notably worse on many of the cognitive function tests, significant decreases in hippocampal volume is "a flag that concussions need to be taken seriously," Bellgowan told The Associated Press.

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