Study Reveals Extent of Traumatic Brain Injuries in NFL Players

A new study presented at the AAN 68th Annual Meeting in Vancouver, Canada, is shedding more light on the incidence and impact of traumatic injuries in NFL players.

Traumatic brain injuries are well known to occur in football players and have been shown to be associated with an increased risk of various neurological disorders, including chronic traumatic encephalopathy. The extent to which brain trauma impact neurological function, however, has yet to be fully elucidated. A new study presented at the American Academy of Neurology (AAN) 68th Annual Meeting in Vancouver, Canada, is shedding more light on the incidence and impact of traumatic injuries in NFL players. The study is one of the largest studies to date in living retired NFL players, according to the study’s lead author, Francis X. Conidi, MD, DO, Florida Center for Headache and Sports Neurology and Florida State University College of Medicine, Tallahassee, FL.

Conidi and colleagues’ used diffusion tensor imaging (DTI) in combination with traditional magnetic resonance imaging (MRI) and thinking and memory tests to study the brains of 40 retired NFL players (mean age, 36 years; range, 27-56 years). DTI is a sensitive MRI technique that enables visualization and characterization of white matter fascicles. Using DTI, more than 40% of retired NFL players were found to have signs of traumatic brain injuries. “The rate of traumatic brain injury was significantly higher in the players than that found in the general population,” noted Conidi in a statement.

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DTI helps determine the level of damage to the brain by showing the movement of water molecules in brain tissue, with water molecule diffusion patterns revealing microscopic details about tissue architecture. Of the 40 former players, 17 (43%) had levels of movement 2.5 standard deviations below those of age-matched healthy people (error rate, <1%). On traditional MRI, 12 (30%) showed evidence of brain injuries from the disruption of nerve axons.

On thinking and memory tests, approximately 50% of players showed significant problems with executive function, 45% with learning or memory, 42% with attention and concentration, and 24% with spatial and perceptual function. The longer a player was in the NFL, the more likely he was to show signs of traumatic brain injury on the advanced MRI. Most of the players in the study were with the NFL approximately 7 years (range, 2-17 years) and had been out of the NFL for less than 5 years.

On average, players reported having sustained 8.1 concussions during their time with the NFL, and 12 players (31%) reported having sustained hits that were officially below the threshold of a diagnosed concussion. No relationships were found, however, between the number of concussions sustained and likelihood of showing evidence of traumatic brain injury on DTI or between the number of years in the NFL and signs of brain damage on traditional MRI.

“This is one of the first [studies] to demonstrate significant objective evidence for traumatic brain injury in these former players,” said Conidi in a statement. “This research in living players sheds light on the possible pathological changes consistent with chronic traumatic encephalopathy that may be taking place.”


Conidi FX. Incidence of traumatic brain injury (TBI) in retired NFL players. Correlation with diffusion tensor (DTI) MRI and neuropsychological testing. Presented at: American Academy of Neurology (AAN) 68th Annual Meeting; April 15-21, 2016; Vancouver, Canada.