Understanding the link between traumatic brain injury and stress

Master’s student Justin Brand (Christie Lab; co-supervised by Dr. Sandy Shultz) has published an article in Neuroscience and Biobehavioral Reviews focusing on the similarities and differences of how the brain responds to stress and traumatic brain injury (TBI).

“The topic of stress and TBI is highly relevant in various populations, including military personnel, intimate partner violence survivors, and individuals exposed to accidents, among others,” says Justin. “But the complex interaction between stress and TBI is not fully understood. By reviewing the existing literature, this article helps provide a comprehensive overview of the current understanding, identify knowledge gaps, and propose future directions for investigation.”

In the review, Justin and his co-authors first show that stress and TBI can cause similar types of damage in the brain. These overlapping injury mechanisms include inflammatory and immune responses, neurotransmitter and ionic disturbances, reactive species production/clearance disturbances, and dysregulation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system.

They also found that the timing of stress can influence TBI outcomes and recovery. Justin and his co-authors found that an individual who faces early life adversity well before a TBI, who deals with an episode of stress immediately before a TBI, or who has a TBI with post-injury stress may suffer more brain damage after their injury. Specifically, these situations could lead to an increased inflammatory response, decreased blood-brain-barrier integrity, increased anxiety-like behaviour, and increased cortical loss (dependent on injury severity).

On the other hand, the literature also suggests that an individual who adequately recovers from an episode of stress before they suffer a TBI may gain some resilience and neuroprotection. This could lead to reduced anxiety-like behaviour and better cognitive recovery after a brain injury.

Justin does note that most of the pre-clinical studies he reviewed only focus on male subjects. “So, not only is further work needed to better understand the temporal relationship between stress and TBI, but there needs to be more work to identify any sex differences,” he says.

“Ultimately, conducting this review on stress and TBI not only helped me personally gain a deeper understanding of the topic to make informed decisions related to my own thesis project, but also hopefully inform future research efforts within the scientific community of the need to consider stress in both pre-clinical and clinical cases of TBI. In doing so, our health care system can utilize new knowledge to implement appropriate care for individuals who have experienced stress and/or TBI.”