Associate Professor Johns Hopkins University School of Medicine Baltimore, Maryland
Abstract Text:
Background: In those with repeated traumatic brain injury (TBI), chronic neuroimmune response may be linked to later onset of memory impairment. Former National Football League (NFL) players have history of repeated TBI incurred through contact sport. [11C]DPA-713 PET (DPA-PET) is a promising neuroimaging technique to quantitatively localize the hypothesized high expression of translocator protein (TSPO), a marker of brain injury and repair, in former NFL players. Here we used DPA-PET in a large cohort of NFL players who left the NFL in the past 10 years and tested for change in TSPO over time.
Methods: DPA-PET was used to quantify regional availability (VT) of TSPO in the brains of 24 recently retired NFL players and 27 age-matched, former elite, non-collision sport athletes. A subset of players returned for DPA-PET at two-year follow-up visit. Neuropsychological assessments and magnetic resonance imaging were obtained. A mixed factors ANOVA was used to examine group differences in VT across regions of interest. TSPO (rs6971) genotype was included as a between-subjects factor.
Results: DPA VT values were higher in NFL players compared to non-collision sport athletes (P < 0.001), with largest differences in hippocampus, supramarginal cortex, and cingulate cortex (each P< 0.001). Former NFL players performed worse in verbal learning and memory. There were no group differences in regional brain volumes. At follow-up (N=7), there was no change in regional DPA VT. Longitudinal data collection is ongoing.
Conclusion: These data support a persistent microglial activation among former NFL athletes. Future work should characterize the microglial response further and its potential link to memory.