Nov. 27 (UPI) -- Just a single season on the gridiron is enough to trigger measurable changes in the brains of some school-age football players.
After a year of playing football, researchers found student athletes with a history of concussion and high impact exposure experience change to their default mode network, a neural network most active during wakeful rest. Decreased DMN connectivity has been associated with both traumatic brain injuries and mental disorders.
"The DMN exists in the deep gray matter areas of the brain," Elizabeth M. Davenport, a postdoctoral researcher at the University of Texas Southwestern Medical Center's O'Donnell Brain Institute, said in a news release. "It includes structures that activate when we are awake and engaging in introspection or processing emotions, which are activities that are important for brain health."
Scientists also analyzed the DMN changes among football players without a history of concussion.
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"Over a season of football, players are exposed to numerous head impacts. The vast majority of these do not result in concussion," said Gowtham Krishnan Murugesan, a doctoral student in biomedical engineering at UT Southwestern. "This work adds to a growing body of literature indicating that subconcussive head impacts can have an effect on the brain. This is a highly understudied area at the youth and high school level."
Researchers used accelerometers inside helmets -- technology known as the Head Impact Telemetry System, or HITS -- to monitor the impacts experienced by 26 youth football players between the ages of 9 and 13.
After a season of monitoring, players were divided into two groups based on concussion exposure. In addition to high and low exposure groups, researchers included a control group of non-contact peers. Students with a prior history of concussions were excluded from the analysis.
Researchers used resting functional MRI images captured before and after the season to measure changes to the players' DMN activity. Machine learning helped scientists identify changes.
"Machine learning has a lot to add to our research because it gives us a fresh perspective and an ability to analyze the complex relationships within the data," said Murugesan. "Our results suggest an increasing functional change in the brain with increasing head impact exposure."
In a second study, researchers looked at the neural impacts of football on high school players, including players who had suffered at least one concussion during the previous season. Scientists used magnetoencephalography scans to analyze changes among the eight brain regions of the DMN.
Players with a history of concussions experienced a decrease in DMN activity during the following season, while concussion-free players showed an increase in activity over the course of the season.
The findings suggest the impacts of concussion can have significant longterm impact on brain development.
"The brain's default mode network changes differently as a result of previous concussion," Davenport said. "Previous concussion seems to prime the brain for additional changes. Concussion history may be affecting the brain's ability to compensate for subconcussive impacts."
Scientists presented the results of both studies on Monday at the annual meeting of the Radiological Society of North America, held this week in Chicago.
