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Traumatic Brain Injury

Long Football Careers Linked to Impulsivity and Brain Damage

White matter loss in the brain can appear earlier than CTE, may impact behavior.


A recent study published in Brain Communications suggests an increased risk of white matter loss that can appear earlier than chronic traumatic encephalopathy (CTE), which may explain cognitive and behavior problems for tackle football players who have long careers.

“American football players and other individuals exposed to repetitive head impacts can exhibit a constellation of later-life cognitive and neuropsychiatric symptoms,” wrote researchers at the Boston University CTE Center who conducted the study. “While tau-based diseases such as chronic traumatic encephalopathy can underpin certain symptoms, contributions from non-tau pathologies from repetitive head impacts are increasingly recognized.”

American football is a popular contact sport and a top fan favorite. Statista estimates over 12 million Americans over the age of six years old played football in 2021, consisting of 5.23 million tackle football players and 6.89 million flag football players. Football is the fan favorite in America, according to another Statista survey of over 7,900 U.S. adults polled during the period July 2021 to June 2022. American football was followed by 74.5% of U.S. sports fans, much more than other sports (56.6% basketball, 50.5% baseball, 21.6% soccer, 21.1% hockey, 15.5% tennis, 14.6% motorsports, 19.7% golf, 16.7% MMA, and 23.4% boxing).

Risks of Playing Football

There is an increased risk of decreased white matter in the brain which may lead to cognitive issues and impulsivity for those who have started playing tackle football at an early age or for over 11 years according to Boston University CTE Center researchers.

“Participation in American football is associated with exposure to repetitive head impacts (RHI) that can lead to symptomatic concussions and asymptomatic sub-concussions,” the scientists wrote. “These impacts are associated with cognitive deficits and neuropsychiatric disturbances later in life.”

What is White Matter?

The central nervous system consists of gray matter (substantia grisea) and white matter (substantia alba). In the brain the gray matter is on the outside, and the white matter is on the inside, whereas in the spinal cord it is the reverse with white matter surrounding the gray matter inside.

Gray matter processes and interprets information in the brain. Gray matter is located on the surface (cortical) and is the outermost layer of the brain consisting mostly of round, central cell bodies of neurons. The gray color is due to the gray nuclei of those cell bodies. In living humans, the gray matter has a pinkish and brownish hue due to numerous capillaries.

White matter connects nerve cells (neurons) and conveys information with electrical impulses from one part of the brain to another. White matter, found in the deeper tissues of the brain (subcortical), is mostly nerve fibers (axons) that transmit signals, and owes its color to the myelin sheath, a white-colored fatty substance that surrounds the axons.

“White matter injury is the cardinal pathology of acute traumatic brain injury, and exposure to RHI can also lead to white matter injury,” wrote the scientists. “Diffusion tensor imaging studies have found white matter changes following just one season of contact sport play, even in the absence of a clinically diagnosed concussion.”

Increased Risk With Longer Football Careers

The scientists performed immunoassays on white matter tissue samples from the dorsolateral frontal brain region of over 200 male deceased donors who had played football. The researchers found decreased myelin proteins were associated with those who played football for over 11 years, and those who started playing tackle football at a young age. “Results suggest that decreased myelin may represent a late effect of repetitive head impacts that contributes to the manifestation of cognitive symptoms and impulsivity,” the researchers concluded.

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