Brain Injury in Retired NFL Players

Based on diffusion tensor imaging, a sensitive MRI scan, researchers found that more than 40% of retired National Football League (NFL) players had signs of traumatic brain injury.

“This is one of the largest studies to date in living retired NFL players and one of the first to demonstrate significant objective evidence for traumatic brain injury in these former players,” said study author Francis X. Conidi, MD, DO (Florida Center for Headache and Sports Neurology and Florida State University College of Medicine, Tallahassee, FL). “The rate of traumatic brain injury was significantly higher in the players than that found in the general population.”

Researchers conducted thinking and memory tests in 40 retired NFL players, along with the brain scans. The players were an average age of 36 (range, 27 to 56). A majority of the players had been out of the NFL for less than five years and played an average of seven years in the NFL (range, 2 to 17 years). They reported an average of 8.1 concussions and 12 players (31%) said they had several sub-concussive hits.

The MRIs measured the amount of damage to the brain’s white matter based on the movement of water molecules in the brain tissue. Seventeen players (43%) had levels of movement 2.5 standard deviations below those of healthy people of the same age, which is considered evidence of traumatic brain injury with a less than 1% error rate. Twelve of the former athletes (30%) showed evidence on traditional MRI of injury to the brain due to disruption of the nerve axons. On the tests of thinking skills, about 50% of the former players had significant problems on executive function, 45% on learning or memory, 42% on attention and concentration, and 24% on spatial and perceptual function.

The more years a player spent in the NFL, the more likely he was to have the signs of traumatic brain injury on the advanced MRI. However, there was no relationship between the number of concussions a player had and whether he had traumatic brain injury based on the advanced MRI. There was also no relationship between the number of years a player spent in the NFL and whether he had signs of brain damage on the traditional MRI.

“We found that longer careers placed the athletes at a higher risk of TBI,” said Conidi. “This research in living players sheds light on the possible pathological changes consistent with chronic traumatic encephalopathy that may be taking place.”

Dr. Conidi will present his findings Tuesday, April 19, 2016 at 5:45 p.m. PT during the Emerging Science session at AAN 2016.

Reference: American Academy of Neurology. Study: More than 40 Percent of Retired NFL Players Had Brain Injury. 11 Apr 2016.