Military services members are vulnerable to traumatic brain injury (TBI). It is presently unknown whether they are at risk for chronic traumatic encephalopathy (CTE) or neurodegenerative proteinopathies such as Alzheimer’s disease (AD), due to TBI with or without blast. We therefore studied veterans for proteinopathy, as it relates to military service and TBI history.

CTE is conceptualized as a progressive proteinopathy due to repetitive head trauma. Studies show an increased risk of clinical AD with moderate and severe TBI. However, current paradigms are driven largely by case studies in athletes whose neurotrauma exposure may be inapplicable to military service-related TBI.

In this cross-sectional survey of autopsy neuropathology in former military services members, brain specimens from 21 subjects were examined. Next-of-kin consented to donation and research. Proteinopathy burden (Braak staging, and modified CERAD score) was compared to age-matched controls. Whole-mount sledge microtome sections with free floating p-tau immunohistochemistry were also examined.

20 out of 21 decedents were male, with a mean age of 66.2 (range 32-94). 14 had a history of psychiatric problems, including PTSD in 10. 5 had neurological problems including stroke and seizure. 1 subject had early onset AD. 4 subjects had a history of TBI and 3 had a history of blast exposure. Neuropathological examination changes ranged from AD neuropathologic change A0B1C0 to A3B3C3 by consensus guidelines. None of the cases showed changes specific for CTE pathology. No relationship was found between p-tau burden (Braak stage) or amyloid-β burden (modified CERAD plaque score) and TBI, blast exposure, or psychiatric signs. P-tau in the amygdala showed no correlation with PTSD history.

These preliminary studies argue against military service as a risk for CTE pathology or neurodegenerative proteinopathy. More research is needed to study the relationship, if any, between TBI and neurodegenerative proteinopathy.