Investigating the role of premorbid chronic stress in TBI recovery in mice: A pilot study

Traumatic brain injury (TBI) is a prominent cause of premature death, disability, and financial burden worldwide. Prolonged exposure to stress serves as a precursor to several mental health conditions that are known to complicate the process of recovery from TBI. Animal models offer unique utility to the study of this intersection of affective disorders and TBI. Thus, the purpose of this study was to ascertain the significance of premorbid stress exposure as a risk factor for functional and psychological deficits following TBI in mice. A Chronic Unpredictable Mild Stress protocol was employed to induce stress, then both the stressed and non-stressed mice were then randomly assigned to receive either an impact or sham surgery procedure. All mice were assessed for signs of functional recovery and underwent comprehensive behavior testing. Findings from this study indicated that exposure to stress contributed to variable behavior responses in both the acute (two weeks) and post-acute (one month) stages of TBI recovery. Further, differences in anxiety and depression-like behaviors were more pronounced among mice that sustained a moderate TBI, compared to a mild injury. Future research should continue to refine both the procedure for inducing concussion and mild TBI in mice, as well as the procedures for assessing the nuanced functional and behavioral recovery in this population to better understand vulnerability factors that contribute to prolonged recovery.