More Medical Evidence on the Toll of Sub Concussive Trauma in Combat Sports

Adding to this site’s archived medical literature addressing safety issues in combat sports, an important study was published this week in the Journal of the American Medical Association addressing objective brain changes in college football players.

The study compared three groups:

1. College football players with no concussion history

2. College football players with a concussion history

3.  A control group of non football players

The study found that the football players with no concussion history had smaller hippocampal volumes than the control group and the players with a concussion history had an even more reduced volume.

Perhaps more importantly the study showed that “there was a statistically significant inverse relationship between left hippocampal volume and number of years of football played“.  In other words, the more years playing football, the greater changes in the brain.

This study adds to the literature strongly suggesting that repeated sub concussive hits (ie – checking in hockey, contact in football and striking in combat sports) do take their toll over time.

As previously discussed, the relevant lesson from studies such as these is that there is a shelf life for combat sports participation and further that hard sparring takes its toll.  The brain can only take a finite number of jostles before negative repercussions take place.  Combat athletes would do well to not only be aware of this but to spar smart and not expose themselves to unneeded damage while training.

Below is the full abstract of the recent study.

_________________________________________________________________

Importance  Concussion and subconcussive impacts have been associated with short-term disrupted cognitive performance in collegiate athletes, but there are limited data on their long-term neuroanatomic and cognitive consequences.

Objective  To assess the relationships of concussion history and years of football experience with hippocampal volume and cognitive performance in collegiate football athletes.

Design, Setting, and Participants  Cross-sectional study conducted between June 2011 and August 2013 at a US psychiatric research institute specializing in neuroimaging among collegiate football players with a history of clinician-diagnosed concussion (n = 25), collegiate football players without a history of concussion (n = 25), and non–football-playing, age-, sex-, and education-matched healthy controls (n = 25).

Exposures  History of clinician-diagnosed concussion and years of football experience.

Main Outcomes and Measures  High-resolution anatomical magnetic resonance imaging was used to quantify brain volumes. Baseline scores on a computerized concussion-related cognitive battery were used for cognitive assessment in athletes.

Results  Players with and without a history of concussion had smaller hippocampal volumes relative to healthy control participants (with concussion: t48 = 7.58; P < .001; mean difference, 1788 μL; 95% CI, 1317-2258 μL; without concussion: t48 = 4.35; P < .001, mean difference, 1027 μL; 95% CI, 556-1498 μL). Players with a history of concussion had smaller hippocampal volumes than players without concussion (t48 = 3.15; P < .001; mean difference, 761 μL; 95% CI, 280-1242 μL). In both athlete groups, there was a statistically significant inverse relationship between left hippocampal volume and number of years of football played (t46 = −3.62; P < .001; coefficient = −43.54; 95% CI, −67.66 to −19.41). Behavioral testing demonstrated no differences between athletes with and without a concussion history on 5 cognitive measures but did show an inverse correlation between years of playing football and reaction time (ρ42 = −0.43; 95% CI, −0.46 to −0.40; P = .005).

Conclusions and Relevance  Among a group of collegiate football athletes, there was a significant inverse relationship of concussion and years of football played with hippocampal volume. Years of football experience also correlated with slower reaction time. Further research is needed to determine the temporal relationships of these findings.

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