White Matter Hyperintensities and Mild TBI in Post-9/11 Veterans and Service Members

The neurobehavioral significance of white matter hyperintensities (WMHs) seen on magnetic resonance imaging after traumatic brain injury (TBI) remains unclear, especially in Veterans and Service Members with a history of mild TBI (mTBI). In this study, we investigate the relation between WMH, mTBI, age, and cognitive performance in a large multisite cohort from the Long-term Impact of Military-relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium. The neuroimaging and neurobehavioral assessments for 1,011 combat-exposed, post-9/11 Veterans and Service Members (age range 22-69 years), including those with a history of at least 1 mTBI (n = 813; median postinjury interval of 8 years) or negative mTBI history (n = 198), were examined. White matter hyperintensities were present in both mTBI and comparison groups at similar rates (39% and 37%, respectively). There was an age-by-diagnostic group interaction, such that older Veterans and Service Members with a history of mTBI demonstrated a significant increase in the number of WMHs present compared to those without a history of mTBI. Additional associations between an increase in the number of WMHs and service-connected disability, insulin-like growth factor-1 levels, and worse performance on tests of episodic memory and executive functioning-processing speed were found. Subtle but important clinical relationships are identified when larger samples of mTBI participants are used to examine the relationship between history of head injury and radiological findings. Future studies should use follow-up magnetic resonance imaging and longitudinal neurobehavioral assessments to evaluate the long-term implications of WMHs following mTBI.