Study identifies microstructural brain changes from heading in amateur soccer athletes

A brain imaging technique developed by Columbia researchers has identified areas in the brain's cerebral cortex-just behind the forehead-that are most damaged by the repetitive impacts from heading a soccer ball. Their study also found that the damage leads to cognitive deficits seen in soccer players who head the ball frequently. 

The study, published Sept. 18 in JAMA Network Open, was conducted in amateur adult soccer players from New York City. 

What's important about our study is that it shows, really for the first time, that exposure to repeated head impacts causes specific changes in the brain that, in turn, impair cognitive function."

Michael Lipton, MD, PhD, study leader, professor of radiology and biomedical engineering at Columbia University Vagelos College of Physicians and Surgeons

The study also gives researchers a brain imaging tool they need to detect these injuries in individuals, learn more about the ways repetitive head impacts affect the brain, and develop treatments. 

A second study from Lipton's lab, in press in the journal Neurology, used a different imaging technique to look at the brain and found related damage in the same area. 

"The fact that both techniques, looking at two different features, find the same association strengthens our conclusion that these changes are mediating heading's cognitive effects," Lipton says. 

Finding signs of brain injury 

The researchers used a new imaging technique to look for biomarkers of injury due to heading in an area of the brain previously inaccessible to accurate imaging. 

Using diffusion MRI, a technique that examines cellular microstructure and organization, the researchers imaged the athletes' brains to look at the interface between white and gray matter in the cerebral cortex, the outermost surface of the brain. 

"We looked at this interface because white and gray matter have different densities and move at different rates in response to head impact," Lipton says. "That creates shear forces between the two types of tissue, leaving the interface between the two layers vulnerable to injury." 

Typical dMRI techniques work well for analyzing structures deep inside the brain, but significant hurdles limit their ability to analyze the outer layers-the very areas that may be most susceptible to injury from heading. A graduate student in Lipton's lab, Joan Song, developed a new method to characterize microstructure within the transition zones between gray and white matter in the brain's outer surface. 

"In healthy individuals, there's a sharp transition between these tissues," Song says. "Here we studied if an attenuation of this transition may occur with minor impacts caused by heading." 

What the study found 

Lipton's team performed dMRI scans on 352 adult amateur soccer players, who reported varying levels of heading over the previous year, and on 77 aged-matched athletes not involved in collision sports. All players took simple learning and memory tests. 

The most fervent headers of the ball-reporting more than 1,000 headers each year-had significantly fuzzier transitions between gray and white matter in the orbitofrontal region but not in other regions further back in the brain. Players who most frequently headed the ball also performed a few points worse on tests of learning and memory compared to players who did little to no heading. 

Greater damage in the transition zone linked head impacts to worse test performance.

"It's very strong evidence that these microstructural changes are likely to be a cause of cognitive deficits," Lipton says. 

What's next? 

The lab is now looking at the potential relationship between these biomarkers and the later development of chronic traumatic encephalopathy (CTE), a neurodegenerative disease that has been diagnosed in athletes who experienced many head impacts over their playing careers. 

"The location of the abnormality we report is remarkably similar to CTE pathology, though we don't yet know if they are linked to CTE or if any of these currently healthy athletes will develop CTE." 

Lipton's lab is also investigating if cardiovascular activity can help buffer the brain from damage caused by repetitive impacts.