Myelin water fraction decrease in mild traumatic brain injury

The increased incidence of reported traumatic brain injury (TBI) and its potentially serious long-term consequences have enormous clinical and societal impacts. The diffuse and continually evolving secondary changes after TBI make it challenging to evaluate the changes in brain-behaviour relationships. In this study we used myelin water imaging to evaluate changes in myelin water fraction (MWF) in individuals with chronic brain injury and evaluated their cognitive status using the NIH Toolbox Cognitive Battery. Twenty-two adults with mild or severe brain injury and twelve age, gender and education matched healthy controls took part in this study. We found a significant decrease in global white matter MWF in individuals with mild TBI compared to the healthy controls. Significantly lower MWF was evident in most white matter ROIs examined including the corpus callosum (separated into genu, body and splenium), minor forceps, right anterior thalamic radiation, left inferior longitudinal fasciculus; and right and left superior longitudinal fasciculus and corticospinal tract. No significant correlations were found between MWF in mild TBI and the cognitive measures. These results show for the first time the loss of myelin in chronic mild TBI.