A build-up of plasma tau may be a factor in chronic neurological symptoms seen in people who sustain one or more traumatic brain injuries (TBI), according to a study published in JAMA Neurology.
Elevated concentrations of tau in the blood are common shortly after TBI, however it is not known how or if these elevated levels play a role in the development of chronic symptoms, including post-concussive disorder, post-traumatic stress disorder (PTSD), depression, and chronic traumatic encephalopathy.
Anlys Olivera, PhD, of the National Institutes of Health, and colleagues assessed peripheral tau levels in military personnel exposed to TBI. Total plasma tau levels were measured, and the Warrior Administered Retrospective Casualty Assessment Tool was used to classify participants with and without self-reported TBI. Self-reported symptoms of post-TBI chronic neurological symptoms were determined using the Neurobehavioral Symptom Inventory, the Posttraumatic Stress Disorder Checklist Military Version, and the Quick Inventory of Depressive Symptomatology.
In total, 70 participants with self-reported TBI and 28 controls with no TBI exposure were included in the study. Those with self-reported TBI had significantly higher concentrations of plasma tau compared to controls (mean [SD], 1.13 [0.78] vs 0.63 [0.48] pg/mL, respectively; F1,97 = 4.97;P = .03). Among those with self-reported TBI, plasma total tau concentrations were significantly associated with having a past medical record of TBI compared with having self-reported TBI only (mean [SD], 1.57 [0.92] vs 0.85 [0.52] pg/mL, respectively; F1,69 = 6.15; P = .02) and reporting the occurrence of three or more TBIs during deployment compared with fewer than three TBIs (mean [SD], 1.52 [0.82] vs 0.82 [0.60] pg/mL, respectively;F1,69 = 8.57; P = .008). In the self-reported TBI group, severity of total post-concussive symptoms correlated with total tau concentrations (r = 0.37; P = .003).
Multiple TBI is therefore significantly associated with long-term elevations of total tau, which may be associated with chronic post-concussive symptoms.
Approximately one-third of military personnel who deploy for combat operations sustain 1 or more traumatic brain injuries (TBIs), which increases the risk for chronic symptoms of postconcussive disorder, posttraumatic stress disorder, and depression and for the development of chronic traumatic encephalopathy. Elevated concentrations of tau are observed in blood shortly following a TBI, but, to our knowledge, the role of tau elevations in blood in the onset and maintenance of chronic symptoms after TBI has not been investigated.
Researchers assessed peripheral tau levels in military personnel exposed to TBI and examined the relationship between chronic neurological symptoms and tau elevations.