Recent research suggests that levels of blood protein tau—already reportedly linked to acute symptoms following traumatic brain injury (TBI)—may also be responsible for the long-term complications resulting from TBI.
The study is from the National Institute of Nursing Research (NINR)—a component of the National Institutes of Health (NIH)—and appears in the August 3 issue of JAMA Neurology, according to a news release from NIH.
About one-third of all US military personnel who serve in combat operations experience at least one TBI, according to the release.
Individuals with TBI are more likely to experience ongoing complications such as post-concussive disorder (PCD), post-traumatic stress disorder (PTSD), and depression, and are also more likely to develop chronic traumatic encephalopathy (CTE), the release notes. However, there is currently no way to identify those who are at greatest risk for developing these chronic symptoms.
To help identify biomarkers to better pinpoint those at-risk, a research team—led by NIH Lasker Clinical Research Scholar and Chief of NINR’s Brain Injury Unit, Tissue Injury Branch Jessica Gill, PhD, RN—explored whether elevated levels of tau are related to chronic neurological symptoms in military personnel who had experienced TBI, the release continues.
The research team used standard assessments to measure PTSD, depression, and other neurological and psychological symptoms among the study participants—70 military personnel with a history of TBI and 28 without a history of TBI. Additionally, researchers took blood samples from each participant.
Additionally, the release explains, the research team used an ultra-sensitive immunoassay technology to measure levels of tau in the blood months and years after the study participants (in this case, military personnel) had experienced TBI.
Per the release, the immunoassay technology is reportedly 1,000 times more sensitive than conventional measurement methods.
Via this method, the research team found elevated tau levels in the blood samples of the military participants with a history of TBI compared with participants who had never suffered a TBI, according to the release.
These elevated levels of tau—a protein reportedly known to have a role in the development of Alzheimer’s disease and Parkinson’s disease—are associated with chronic neurological symptoms, including PCD, during which an individual has symptoms such as headache and dizziness in the weeks and months after injury, the release explains.
Chronic neurological symptoms have reportedly been linked to CTE—progressive brain degeneration that leads to dementia following repetitive TBIs—independent of other factors such as depression and PTSD, the release continues.
Findings from this study suggest that long after TBI occurs, tau accumulations alone may contribute to chronic neurological symptoms, according to the release.
Additionally, per the release, researchers found that participants with three or more deployment-related TBIs had significantly higher levels of tau compared with participants who had fewer TBIs.
Gill notes in the release that the study was limited to identifying the effects of tau accumulation in military personnel who experienced long-term neurological symptoms after a TBI.
“With further study, our findings may provide a framework for identifying patients who are most at risk for experiencing chronic symptoms related to TBI,” Gill adds in the release.
“Identifying those at risk early in the progression of the disease provides the best opportunity for therapies that can lessen the cognitive declines that may result from these long-term effects,” Gill concludes.
[Source: National Institutes of Health]