Heading a soccer ball messes with your brain

As the seconds tick away in a tie game, you run down the field and find an opening, and the perfect cross comes in from your mate. You burst forward, put a perfect header past the goalie and into the corner of the net, and you're the hero.

And also, from a cognitive and electrophysiological perspective, you're dumber.

A study that's just come out by a team at a number of UK universities, chief among them the University of Stirling in Scotland, claims to have the first set of concrete evidence of neurological changes due to heading a ball.

The "immediate alterations in brain electrophysiological and cognitive function" were demonstrated "by a cohort of healthy, young soccer players," the researchers wrote in the study published in EBioMedicine.

Each of the 19 test subjects took 20 headers from a ball machine that shot them out at 30-50 kilometers per hour (18-30 mph), firing perfect crosses designed to resemble corner kicks. Once the players had performed 20 headers over a period of ten minutes, their brains were tested.

Seventy-four percent showed immediate neurochemical alteration and decreased cognitive skills, i.e. memory function.

With regard to cognitive changes, the players were asked to perform short-term memory tests, and immediately after heading, the results compared to baseline performance showed reduction in memory between 47 and 61 percent.

With regard to neurochemical alteration, the researchers were looking for changes in levels of GABA, the main inhibitory chemical in the brain that affects our ability to control our muscles. In other words, the more GABA present in the brain, the less control an individual has over his or her motor functions. Increased GABA levels result in a longer "cortical silent period," or a pause that directly follows voluntary muscle movement. This cortical silent period increased five percent immediately after heading compared to the baseline levels measured before. Researchers viewed the change using electromagnetic analysis - the first time the technology has been used in such an experiment.

The players had their brains analyzed immediately after the heading - but also 24 hours, 48 hours and two weeks afterwards. The good news is that the changes seen immediately following the heading disappeared in each of the subsequent tests. There were negligible or no differences with regard to cognitive performance or neurochemical makeup.

Does this mean that heading a soccer ball isn't dangerous in the long run? Not exactly, says leading author Magdalena Ietswaart of the University of Stirling. She points out that "there are no known safe levels of soccer heading" and compares the effects of "sub-concussive trauma" to the consumption of alcohol.

"The research we have done is just a first step on the journey of finding out what is the true impact of football heading," she writes, stressing that it remains unknown what impact the beautiful game has on brain development and long-term neurological health.