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New football study shows concussions don't happen from a single blow

Kathleen Blanchard's picture
Study finds it takes a series of hits versus one blow for a concussion to occur.

A new study shows football concussions come from multiple blows to the head rather than a single injury as commonly thought.

In a two year study of football players, researchers found concussions are the result of many hits that happen over time throughout the football season.

For this study Purdue university scientists studied football players from Jefferson High School in Lafayette, Indiana.

Information was obtained from helmet sensor data, brain imaging studies and cognitive tests performed on the players before during and after two seasons.

Cognitive screening was performed with a computer program. The scientists used functional MRI (fMRI) studies during the computer tests to find out which area of the brain was most active when the players performed certain tasks.

The results showed the players were using different approaches to perform tasks, indicating brain changes that require adaptation.

Thomas Talavage, an expert in functional neuroimaging and co-director of the Purdue MRI Facility explains, “…a player is having to use a different strategy to perform a task, and that is likely because functional capacity is reduced.

He adds “The level of change in the fMRI signal is significantly correlated to the number and distribution of hits that a player takes.”

Performance doesn't change, but Talavage says brain activity does, meaning certain areas are no longer being used to perform tasks.

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Larry Leverenz, an expert in athletic training and a clinical professor of health and kinesiology says most clinicians would say you don’t have a concussion if you don’t have symptoms.

Contrary to conventional belief, he says there brain changes that happen before symptoms of a concussion occur.

The scientists say they’re not sure yet what the changes mean in terms of cognitive impairment, but they note “any change…is a concern.”

The study also showed the area of the brain affected from repeated impact is associated with chronic traumatic encephalopathy (CTE), a neurodegenerative brain disorder that can lead to severe disability.

The authors say the finding, published in the Journal of Biomechanics, may mean football players should be limited in the number of blows to the head they’re allowed to take in a season. The study was small and Talavage says more subjects are needed to continue understanding how to prevent football concussion.

The researchers are planning on studying another high school team in addition to a girl's soccer team to see if girls are affected differently than boys. They also want to see what happens to the brain in athletes that don’t wear head protection.

The research group, Purdue Neurotrauma Group (PNG) is also studying ways to help soldiers who suffer concussions from explosions and shock waves.

"The most important implication of the new findings is the suggestion that a concussion is not just the result of a single blow, but it's really the totality of blows that took place over the season," said Eric Nauman, an associate professor of mechanical engineering and an expert in central nervous system and musculoskeletal trauma."

The finding from fMRI’s and cognitive testing of the football players in the study shows a series of hits happen before concussion symptoms occur.

Purdue University
February 2, 2012