A single season of high school football may cause microscopic changes in the structure of the brain, according to a new study. A new type of magnetic resonance imaging (MRI) revealed significant changes in the structure of the gray matter in the front and rear of the brain and changes to structures deep inside the brain. The study is published in Neurobiology of Disease. ?

The researchers used a magnetic resonance imaging (MRI) to take brain scans of 16 high school players, ages 15 to 17, before and after a season of football. They found significant changes in the structure of the gray matter in the front and rear of the brain, where they are most likely to occur, as well as changes to structures deep inside the brain. All participants wore helmets, and none received head seve severe enough to constitute a concussion.

Concerning trends

One bonk to the head may be nothing to sweat over. But mounting evidence shows that repeated blows to the cranium – such as those racked up while playing sports like hockey or football, or through blast injuries in military combat – may lead to long-term cognitive decline and increased risk of neurological disorders, even When the blows do not cause concussion.

Over the past decade, researchers have found that an alarming number of retired soldiers and college and professional football players show signs of a newly identified neurodegenerative disease called chronic traumatic encephalopathy (CTE), which is characterized by a buildup of pathogenic tau protein in the brain .

"There is a lot of emerging evidence that just playing impact sports actually changes the brain, and you can see these changes at the molecular level in the accumulations of different pathogenic proteins associated with neurodegenerative diseases like Parkinson's and dementia," Liu said. "We wanted to know when this happened – how early does this occur?"

A matter of gray and white

The brain is built of white matter, long neural wires that pass messages back and forth between different brain regions, and gray matter, tight nets of neurons that give the brain its characteristic wrinkles. Recent MRI studies have shown that playing a season or two of high school football can weaken white matter, which is mostly found nestled in the interior of the brain. Liu and his team wanted to know if repetitive blows to the head could also affect the brain's gray matter.

The researchers used a new type of MRI called diffusion kurtosis imaging to examine the intricate neural tangles that make up gray matter. They found that the organization of the gray matter in players 'brains changed after a season of football, and these changes correlated with the number and position of the head measured by accelerometers mounted inside players' helmets.

"Although our study did not look into the consequences of the observed changes, there is emerging evidence suggesting that such changes would be harmful over the long term," Liu said. Tests revealed that students' cognitive function did not change over the course of the season, and it is unclear if these changes in the brain are permanent, say.

"The brain microstructure of younger players is still rapidly developing, and that may be counteracting the alterations caused by repetitive head," said first author Nan-Ji Gong. However, the researchers still need caution – and frequent cognitive and brain monitoring – for youth and high schoolers engaged in impact sports.