The study from researchers at the University of Boston School of Medicine was the first large-scale look into tackle football's effect on youths.
Youth tackle football players are significantly more susceptible to impairments and depression than those who begin playing the sport at an adolescent age or older, according to a new study.
In what they called the first large-sample study of age of first exposure (AFE) to football's effect on behavior, mood and cognition in youths, researchers from Boston University School of Medicine studied 214 former US football players with a series of cognitive scales and tests.
The studied players had no other contact sport history outside of football, and were split into groups defined by if they had begun playing football before age 12, or if they had begun playing at or after age 12.
Researchers reasoned there is data to connect repetitive head impacts (RHI) and long-term neurological issues — especially in players with still-developing bodies.
“Youth football is played between ages of 5 and 14, a period when the brain undergoes substantial maturation in males,” researchers wrote. “Exposure to RHI over a single season of youth football (without diagnosed concussions) has been associated with white matter alterations in 8—13 year olds.”
Participants of the study completed the Brief Test of Adult Cognition by Telephone (BTACT). They also reported their own measures of executive function and behavioral regulation with the Behavior Rating Inventory of Executive Function-Adult Version Metacognition Index (MI), and Behavioral Regulation Index (BRI). They were also gauged for depression through the Center for Epidemiologic Studies Depression Scale (CES-D), and apathy through the Apathy Evaluation Scale (AES).
Results showed that participants from the younger AFE group had a more than twice greater chance of clinical impairment on every measure aside from BTACT. Even worse, they reported a more than 3 times greater chance of clinically elevated depression scores versus the older AFE group.
The mechanisms behind the findings are currently unknown to the researchers, but researchers noted that peak maturation of brain functions and other neurodevelopmental milestones are reached between the ages of 9 and 12 years. Such changes occur to structures such as the hippocampus and amygdala, they wrote, where clinical functions such as emotion regulation and behavior occur.
Using helmet accelerometry, youth American football players experience an estimated median of 252 head impacts per season in one study — and an average of 240 in another study. In a single season of youth football, RHI exposure can alter the left inferior front-occipital fasciculus and right superior longitudinal fasciculus white matter tracts.
“The effects of RHI exposure on the brain at a young age may disrupt neurodevelopment and increase vulnerability to the long-term neuropsychiatric and cognitive impairments associated with prolonged exposure to RHI, aging or likely both,” researchers wrote.
Robert Stern, PhD — a Boston University professor and one of the study’s senior authors — gave definite recommendation on the controversies surrounding youth football and potential neurological damage.
“I’m at a point where I feel comfortable saying that, based on logic and common sense and the growing totality of the research, I don’t think kids should be playing tackle football,” Stern said to the Boston Globe this week.
Another University of Boston-based study was published in the Journal of the American Medical Association last month. It reported that 110 of 111 studied deceased former National Football League (NFL) players had suffered from chronic traumatic encephalopathy (CTE).
Bennet Omalu, MD — volunteer associate clinical professor at the University of California-Davis School of Medicine — was famously credited with discovering the prevalence CTE in the brains of former NFL players. He reacted to the CTE study results by calling youth football “the definition of child abuse,” according to the New York Post.
“What we do as a society is protect children from being exposed to such risk factors,” Omalu said. “We do that with cigarette smoking. We did that with alcohol. Why not football, which is more dangerous?”
The latter study concluded with researchers calling for additional data, “especially large cohort longitudinal studies,” to better understand the long-term clinical implications of youth football in America, researchers wrote.
The study, "Age of first exposure to American football and long-term neuropsychiatric and cognitive outcomes," was published online in Nature Translational Psychiatry this week.