CTE in Professional Soccer Players

A recent study has determined that former professional soccer players had pathologically confirmed CTE at death. As a former collegiate soccer player, I understand the huge amount of head impacts that may occur over a soccer player's career.  It also causes this subject to be closer to my heart, and something I will tend to follow as future research continues.

The studied looked at 14 retired soccer players with progressive cognitive impairment at an average age of 63.6 years and an average disease duration of 10 years. 12 cases died from neurodegenerative disease and  6 participants consented to have post-mortem brain examination, of which all six were determined to have septal abnormalities consistent of chronic repetitive head impacts.  Four of the 6 were confirmed pathologically to have CTE.  This finding is probably related to the numerous head impacts that soccer players can accumulate. Trauma can occur from head-to-head contact or even simply heading the ball.  An average player can head the ball 6-12 times per game and may perform more than 2000 headers during a 20-year career, in addition to heading drills in training (Spiotta, AM. et al., 2012).  Even so, the majority of head injuries in soccer are caused by head-player contact (40%) compared to head-ball (12.6%) (Boden, BP. et al., 1998).  Cognitive and brain structural changes have been reported in soccer players that have been exposed to repetitive subconcussive head impacts (Koerte, IK et al., 2012; Koerte, IK et al., 2015)

The cases in this report all played soccer in the 1980's.  These players would have been exposed to heavier balls, and a corresponding increased impact from headers.  However,  the balls played with today are lighter and move at a greater velocity.  Recent studies have found radiological findings of abnormal white matter microstructure in frequent headers of the ball (Lipton, Ml. et al., 2013) as well as in postmortem findings of CTE in a 29-year-old player with ALS (McKee AC. et al., 2014).  These results may support the idea that these lighter balls may result in the same net force on head impact

Sources
Boden BP, Kirkendall DT, Garrett WE Jr (1998) Concussion incidence in elite college soccer players. Am J Sports Med 26:238–241
Koerte IK, Ertl-Wagner B, Reiser M, Zafonte R, Shenton ME (2012) White matter integrity in the brains of professional soccer players without a symptomatic concussion. JAMA 308:1859– 1861.
Koerte IK, Lin AP, Muehlmann M, Merugumala S, Liao H, Starr T, Kaufmann D, Mayinger M, Steffinger D, Fisch B et al (2015) Altered Neurochemistry in Former Professional Soccer Players without a History of Concussion. J Neurotrauma 32:1287–1293.
Lipton ML, Kim N, Zimmerman ME, Kim M, Stewart WF, Branch CA, Lipton RB (2013) Soccer heading is associated with white matter microstructural and cognitive abnormalities. Radiology 268:850–857
McKee AC, Daneshvar DH, Alvarez VE, Stein TD (2014) The neuropathology of sport. Acta Neuropathol 127:29–51.
Spiotta AM, Bartsch AJ, Benzel EC (2012) Heading in soccer: dangerous play? Neurosurgery 70:1–11.