It turns out that even playing a single season of football can alter a person's brain. Scientists have found that repeated impacts to the heads of high school football players can cause measurable changes to their brains, even when no concussion occurs.

Football has the highest concussion rate of any competitive contact sport. This means that concern over possible head trauma has risen over time, especially when it comes to high school and youth football. That's why researchers are conducting tests to see exactly what occurs to a person's brain when playing football.

"Studies like this are important to understand how and where long-term damage might be occurring, so that we can then take the necessary steps to prevent it," said Elizabeth Davenport of University of Texas Southwestern and one of the researchers involved in the study.

The researchers conducted a pre-season MRI scan of high school varsity players. They also had the players take cognitive tests, which included memory and reaction time tests. During the football season, the players wore sensors in their helmets that detected each impact that they received. Then, post-season, each player had another MRI scan and another round of cognitive tests.

The researchers then used diffusional kurtosis imaging (DKI), which measures water diffusion in biological cells. This allowed them to identify changes in neural tissues and also allowed them to measure white matter abnormalities.

"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," said Joseph Maldjian of UT Southwestern and the senior author of the study. "Work of this type, combining biomechanics, imaging, and cognitive evaluation is critical to improving our understanding of the effects of subconcussive impacts on the developing brain. Using this information, we hope to help keep millions of youth and adolescents safe when engaged in sports activities."

The findings are important for helping prevent injuries and also for showing what happens during high-impact sports. With that said, further studies are needed in order to better understand how these events influence the brain in later years.

The findings are published in the April 2016 edition of the Journal of Neurotrauma.