Advanced MRI reveals damage in brains of retired NFL football players

The brains of 16 retired National Football League players with known cognitive impairment show signs of damaging atrophy, according to advanced MRI studies described Wednesday at the 2009 RSNA annual meeting.

Songyuan Tang, Ph.D., a researcher at the University of North Carolina, presented case reports that represent the latest steps in research by collaborator Kevin Guskiewicz to study the relationship between football-related concussions and cognitive and behavioral problems that emerge long after the men's playing days are over.

Guskiewicz first drew interest to football-related concussions and dementia in 2005 with a study suggesting that a history of three or more concussions was associated with an increased risk of cognitive impairment by age 50. An autopsy study, published by a different group in 2005, found concentrations of tau protein suggesting dementia in the brains of eight of nine former football players.

Guskiewicz's group's survey of 2552 retired pro football players in 2007 revealed that they had a 37% higher risk of Alzheimer's disease than other men their age.

Guskiewicz was a main source for an Oct. 19, 2009, investigational report published in The New Yorker magazine. Here, his colleague Tang described direct physical measures of head blows experienced by UNC football players. His research has indicated that concussive blows are extremely common. The brain stem, frontal lobe, and temporal lobes are particular vulnerable to concussive sports-related injury because of their locations near bony protrusions.

Results presented by Tang at the RSNA meeting don't bode well for the 16 retired NFL players, all over age 50, who volunteered for the study. Tang compared findings of structural MRI and diffusion tensor imaging (DTI), an advanced MRI technique that maps connections between neurons. The brain studies of the retired players were compared with identical studies performed on 10 cognitively normal men in the same age group.

Tang found diffused atrophies in the whole brains of the players that are consistent with those reported in the medical literature for mild cognitive impairment, a condition that often precedes the onset of Alzheimer's disease and dementia.

Gray matter atrophy was identified in the six brain regions for the former players. Tissue losses were measured in the caudate hippocampus, supplementary motor area, medial frontal gyrus, and primary motor cortex.

In terms of white matter differences, fractional anisotropy DTI maps identified clusters of atrophy in five regions: the inferior frontal-occipital fasciculus, genu, sagittal stratum, posterior corona radiata, and splenium.

By applying fiber tractography to scans of one of the NFL subjects and a normal volunteer, Tang discovered a marked reduction in the number of  fiber connections between neurons in the white matter in the left and right hemispheres of the former football player's brain. The affected regions included the genu, sagittal stratum, and splenium.

Tang's results are limited by the small size of the study and other factors. Future research will consider correlations between the player's history of sports-related concussion, career length, and brain atrophy, Tang said.