Associations between Serum Tau, Neurological Outcome, and Cognition following Traumatic Brain Injury

Objective: To investigate the dynamic change in the serum Tau protein early after acute traumatic brain injury (TBI) and its association with neurological outcome and cognitive function. Subjects and Methods: Around 229 patients with acute TBI and 30 healthy subjects were evaluated for the serum levels of Tau protein on 1, 3, 5, 7, and 14 days after TBI. The relationships of the serum levels of Tau protein and initial GCS and GOS at 6 months post-injury were also analyzed. Further, 95 TBI patients were assessed with their cognitive function with Montreal cognitive assessment (MoCA) score. Results: Serum Tau was significantly higher in patients with TBI at 1, 3, 5, 7, and 14 days. The serum Tau at each point was significantly lower respectively in the patients with mild TBI than that in medium and severe TBI. The serum Tau was significantly lower in patients with good outcome compared to the poor outcome group. The early serum Tau was negatively correlated with both GCS and GOS. In the TBI group, 39 (41%) out of 95 patients developed cognitive dysfunction assessed by MoCA. Tau protein at day 1, 3, and 5 after TBI was significantly correlated with cognitive dysfunction at 6 months after TBI. Conclusions: Acute Tau associations with neurological outcomes and cognition may implicate white matter damage and neuronal degeneration. Serum Tau may be used as a reliable biological marker for early diagnosis and cognitive recovery following TBI.