Skip to content

Another study finding brain changes from playing tackle football - this time measurable brain changes were found in boys 8 to 13 years old after just one season of playing football. None of the boys had received a concussion diagnosis during the season. The changes in the white matter of the brain (and detected with magnetic resonance imaging (MRI) were from the cumulative subconcussive head impacts that occur in football - the result of repetitive hits to the head during games and practices.

No one knows if the brains of football players fully recover after the football season. But these findings are worrisome. Especially because last year researchers found that NFL players who had begun playing  football before age 12 had a higher risk of altered brain development, as compared to players who started later (see post). Currently nearly 3 million students participate in youth tackle football programs across the United States. Some are calling for young players to only play flag or touch football, and to only play tackle football starting with the teenage years. From Science Daily:

Brain changes seen in youth football players without concussion

Researchers have found measurable brain changes in children after a single season of playing youth football, even without a concussion diagnosis, according to a new study published online in the journal Radiology.

"Most investigators believe that concussions are bad for the brain, but what about the hundreds of head impacts during a season of football that don't lead to a clinically diagnosed concussion? We wanted to see if cumulative sub-concussive head impacts have any effects on the developing brain," said the study's lead author, Christopher T. Whitlow, M.D., Ph.D., M.H.A., associate professor and chief of neuroradiology at Wake Forest School of Medicine in Winston-Salem, N.C.

The research team studied 25 male youth football players between the ages of 8 and 13. Head impact data were recorded using the Head Impact Telemetry System (HITs), which has been used in other studies of high school and collegiate football to assess the frequency and severity of helmet impacts....The study participants underwent pre- and post-season evaluation with multimodal neuroimaging, including diffusion tensor imaging (DTI) of the brain. DTI is an advanced MRI technique, which identifies microstructural changes in the brain's white matter. 

The brain's white matter is composed of millions of nerve fibers called axons that act like communication cables connecting various regions of the brain. Diffusion tensor imaging produces a measurement, called fractional anisotropy (FA), of the movement of water molecules in the brain and along axons. In healthy white matter, the direction of water movement is fairly uniform and measures high in FA. When water movement is more random, FA values decrease, which has been associated with brain abnormalities in some studies.

The results showed a significant relationship between head impacts and decreased FA in specific white matter tracts and tract terminals, where white and gray matters meet. "We found that these young players who experienced more cumulative head impact exposure had more changes in brain white matter, specifically decreased FA, in specific parts of the brain," Dr. Whitlow said. "These decreases in FA caught our attention, because similar changes in FA have been reported in the setting of mild TBI."

It is important to note that none of the players had any signs or symptoms of concussion."We do not know if there are important functional changes related to these findings, or if these effects will be associated with any negative long-term outcomes," Dr. Whitlow said. "Football is a physical sport, and players may have many physical changes after a season of play that completely resolve. These changes in the brain may also simply resolve with little consequence. However, more research is needed to understand the meaning of these changes to the long-term health of our youngest athletes." [Original study]

Study after study finds negative effects on the brain from playing football - here it is one season of high school football resulting in measurable brain changes. None of these players had a concussion during the season, and so the negative effects were from subconcussive head impacts or hits. Interestingly, those special helmets they wore to measure impacts showed no relationship with what the brain scans showed - so the helmets were basically useless in measuring subconcussive impacts. From Science Daily:

Head impacts from single season of high school football produce measurable change in brain cells

Repeated impacts to the heads of high school football players cause measurable changes in their brains, even when no concussion occurs, according to new research. Researchers gathered data from high school varsity players who donned specially outfitted helmets that recorded data on each head impact during practice and regular games. They then used experimental techniques to measure changes in cellular microstructure in the brains of the players before, during, and after the season.

"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 senior author Dr. Joseph Maldjian, Chief of the Neuroradiology Division and Director of the Advanced Neuroscience Imaging Research Lab, part of the Peter O'Donnell Jr. Brain Institute at UT Southwestern.

In the study, appearing in the Journal of Neurotrauma, a team of investigators at UT Southwestern, Wake Forest University Medical Center, and Children's National Medical Center evaluated about two dozen players over the course of a single football season.....During the pre-season each player had an MRI scan and participated in cognitive testing, which included memory and reaction time tests. During the season they wore sensors in their helmets that detected each impact they received. Post-season, each player had another MRI scan and another round of cognitive tests. 

Researchers then used diffusional kurtosis imaging (DKI), which measures water diffusion in biological cells, to identify changes in neural tissues. ....DKI also allowed the researchers to measure white matter abnormalities. White matter consists of fibers that connect brain cells and can speed or slow signaling between nerve cells. In order 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 TBI.

Football has the highest concussion rate of any competitive contact sport, and there is growing concern -- reflected in the recent decrease in participation in the Pop Warner youth football program -- among parents, coaches, and physicians of youth athletes about the effects of subconcussive 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.