medwireNews: Results from a small study suggest that even a sport-related head impact that does not cause obvious injury, such as "heading" a ball in football or soccer, may result in impaired cognition.
The researchers, led by Anne Sereno (University of Texas, Houston, USA), recruited 24 girls attending high school (median age 16.5 years), of whom half played soccer and half did not, to test their cognitive abilities using a tablet computer-based application.
The test application took the form of a circle surrounded by four boxes that intermittently lit up with a corresponding arrow pointing from the circle to the lit box. For the first "Pro-Point" test, the participants were asked to touch the lit square as quickly as possible each time it changed. A second "Anti-Point" test required the participants to touch the box opposite to the target location.
The team measured three variables - initiation time (time from visual cue appearing to finger movement), movement time (time from first finger movement to touching target), and total time (time from finger movement to touching target goal).
They found that none of the three variables differed significantly between soccer players and nonsoccer players for the Pro-Point test. However, for the Anti-Point test, which requires a voluntary rather than an involuntary response, soccer players had nonsignificantly slower initiation times, at 394 ms versus 378 ms. They also had significantly slower movement times, at 561 ms versus 531 ms, and total times, at 955 ms versus 909 ms.
Using data on heading rate (n=10), years of playing soccer (n=12), and hours of soccer played per week (n=12), for the soccer players, the researchers found that all three variables had marginal effects on scores achieved on the Anti-Point test.
"Though the changes we report were robust, they do not necessarily imply sustained changes or brain injury," say Sereno and co-authors in PLoS ONE. "Further study is needed to track soccer players for longer periods to evaluate if these changes are transient or longer-lasting, if they are dependent upon repeated subconcussive blows, and if they generalize to male soccer players."
They conclude: "To our knowledge, these results provide the first evidence that even subconcussive blows in soccer could lead to measureable, even if possibly transient, cognitive changes in young soccer players."
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