Elevated Tau in Military Personnel Relates to Chronic Symptoms Following Traumatic Brain Injury

Abstract

Objective: To understand the relationships between traumatic brain injury (TBI), blood biomarkers, and symptoms of posttraumatic stress disorder (PTSD), depression, and postconcussive syndrome symptoms.

Design: Cross-sectional cohort study using multivariate analyses.

Participants: One hundred nine military personnel and veterans, both with and without a history of TBI.

Main measures: PTSD Checklist-Civilian Version (PCL-C); Neurobehavioral Symptom Inventory (NSI); Ohio State University TBI Identification Method; Patient Health Questionnaire-9 (PHQ-9); Simoa-measured concentrations of tau, amyloid-beta (Aβ) 40, Aβ42, and neurofilament light (NFL).

Results: Controlling for age, sex, time since last injury (TSLI), and antianxiety/depression medication use, NFL was trending toward being significantly elevated in participants who had sustained 3 or more TBIs compared with those who had sustained 1 or 2 TBIs. Within the TBI group, partial correlations that controlled for age, sex, TSLI, and antianxiety/depression medication use showed that tau concentrations were significantly correlated with greater symptom severity, as measured with the NSI, PCL, and PHQ-9.

Conclusions: Elevations in tau are associated with symptom severity after TBI, while NFL levels are elevated in those with a history of repetitive TBIs and in military personnel and veterans. This study shows the utility of measuring biomarkers chronically postinjury. Furthermore, there is a critical need for studies of biomarkers longitudinally following TBI.

Figure 1.

The results of logistic regression, controlling for age, sex, time since injury, and anti-depressant/anxiety medication. The differences between (1) TBI and controls and (2) 1–2 TBIs and repetitive TBIs, on the 4 concentrations are shown in A. tau; B. Aβ40; C. Aβ42; and D. NFL.