Imaging reveals changes in football players' brains

In a single season, repeated head impacts can cause changes in the brains of high school football players, even when the injury doesn’t rise to the level of a concussion. That’s according to researchers who conducted a study using DKI technology pioneered by scientists who now work at the Medical University of South Carolina. DKI stands for diffusional kurtosis imaging, an MRI method.

In the study, researchers used DKI, which measures water diffusion in biological cells, to identify changes in varsity players’ neural tissues. MUSC radiology professor Jens Jensen, Ph.D., advised on the implementation and interpretation of the DKI technique. DKI was invented by Jensen and fellow MUSC professor Joseph Helpern, Ph.D., 12 years ago, when both were at New York University. They’ve continued to develop this technology for the past five years at MUSC. 

“There were significant correlations between impact exposure and several of the parameters that are measured with DKI,” Jensen said. “These DKI parameters are believed to be sensitive to brain tissue microstructure, so the study provides evidence that a single season of high school football is sufficient to cause microstructural changes, even without clinical evidence of concussion.”

Jensen said it’s important to note that this is a preliminary study. It appears in the Journal of Neurotrauma.

Investigators from the University of Texas Southwestern Medical Center, Wake Forest University Medical Center and Children’s National Medical Center at George Washington University School of Medicine conducted the study. They studied players who wore helmets that recorded data on each head impact during practice and regular games. The researchers measured changes in cellular microstructure in the athletes’ brains of the players before, during and after the season.

Joseph Maldjian, M.D., chief of the Neuroradiology Division and director of the Advanced Neuroscience Imaging Research Lab at UT Southwestern, was lead author of the study. A report from UT Southwestern quoted him as saying, “Our findings add to a growing body of literature demonstrating that a single season of contact sports can result in brain changes regardless of clinical findings or concussion diagnosis.” 

The group of about two dozen players was not large enough to draw conclusions about the differences in impacts between positions, researchers said. 

During the pre-season, each player had an MRI scan and cognitive testing, which included memory and reaction time tests. During the season, the players had sensors in their helmets that detected each impact. Post-season, each player had another MRI scan and more cognitive tests. Researchers then used DKI to check for changes.

DKI analysis has been used to study brain development, as well as brain injury and disease, including autism spectrum disorders, attention deficit hyperactivity disorder, Alzheimer’s disease, traumatic brain injury, stroke, schizophrenia and mild cognitive impairment.

DKI also allowed the researchers to measure white matter abnormalities. White matter consists of fibers that connect brain cells and can speed up or slow down signaling between nerve cells. For the brain to reorganize connections, white matter must be intact, and the degree of white matter damage may be one factor that limits the ability of the brain to reorganize connections following traumatic brain injury.

UT Southwestern quoted Maldjian as saying work of this type, combining biomechanics, imaging and cognitive evaluation, is critical to improving the understanding of the effects of sub-concussive impacts on the developing brain. “Using this information, we hope to help keep millions of youth and adolescents safe when engaged in sports activities,” Maldjian said.

Football has the highest concussion rate of any competitive contact sport, and there is growing concern among parents, coaches and pediatricians about the effects of sub-concussive head impacts, those not directly resulting in a concussion diagnosis, researchers noted. 

Previous research has focused primarily on college football players, but recent studies have shown impact distributions for youth and high school players to be similar to those seen at the college level, with differences primarily in the highest impact magnitudes and total number of impacts, the researchers noted.

Support came from the National Institutes of Health, Childress Institute for Pediatric Trauma at Wake Forest Baptist Medical Center and a National Science Foundation Graduate Research Fellowship grant.

Jensen said he was pleased to be part of the study. “My role was quite small, although I am gratified that the technique I helped to develop is finding useful applications.”

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Portions of this article were pulled from a news release by the University of Texas Southwestern.