Chronic Traumatic Encephalopathy Neuropathologic Change in Military Veterans

The Department of Defense Blast Injury Research Program Coordinating Office held an International State-of-the-Science Meeting in 2015 to consider and reach consensus about the current body of knowledge relating to chronic traumatic encephalopathy (CTE) in the military. The two biggest future priority areas identified at that time related to the need for more research on CTE neuropathologic change (CTE-NC) and more research on clinical diagnostic criteria. Both have occurred and have yielded important findings. This commentary article addresses these two high priority recommendations, a decade after the state-of-the-science meeting, by reviewing recently published studies. We also add new data to the literature relating to CTE-NC in military veterans. We examined data from the Lieber Institute for Brain Development brain repository. Brain donors were 163 men with a mean age of 66 years at the time of death (range = 50-96), 70 of whom served in the military (42.9%), with 15 reportedly experiencing combat (9.2%). Tissue samples were screened to determine if they had definitive CTE-NC or 'features' of CTE-NC. No case had definitive CTE-NC. There were 4.3% of the civilian group who had 'features of CTE-NC' (4/93) and 7.1% of the veteran group had features of CTE-NC (5/70). Based on our review it is unclear how common CTE-NC is in military veterans; it is possible that it is uncommon. There are no validated clinical diagnostic criteria for CTE, and recent studies have illustrated that CTE-NC is not associated with depression, suicidality, anxiety, irritability, impulsivity, explosivity, verbal violence, physical violence, or substance abuse.