Neurodegenerative Disorders in the Context of Vascular Changes after Traumatic Brain Injury

Traumatic brain injury (TBI) results from external biomechanical forces that cause structural and physiological disturbances in the brain, leading to neuronal, axonal, and vascular damage. TBIs are predominantly mild (65%), with moderate (10%) and severe (25%) cases also prevalent. TBI significantly impacts health, increasing the risk of neurodegenerative diseases such as dementia, post injury. The initial phase of TBI involves acute disruption of the blood–brain barrier (BBB) due to vascular shear stress, leading to ischemic damage and amyloid-beta accumulation. Among the acute cerebrovascular changes after trauma are early progressive hemorrhage, micro bleeding, coagulopathy, neurovascular unit (NVU) uncoupling, changes in the BBB, changes in cerebral blood flow (CBF), and cerebral edema. The secondary phase is characterized by metabolic dysregulation and inflammation, mediated by oxidative stress and reactive oxygen species (ROS), which contribute to further neurodegeneration. The cerebrovascular changes and neuroinflammation include excitotoxicity from elevated extracellular glutamate levels, coagulopathy, NVU, immune responses, and chronic vascular changes after TBI result in neurodegeneration. Severe TBI often leads to dysfunction in organs outside the brain, which can significantly impact patient care and outcomes. The vascular component of systemic inflammation after TBI includes immune dysregulation, hemodynamic dysfunction, coagulopathy, respiratory failure, and acute kidney injury. There are differences in how men and women acquire traumatic brain injuries, how their brains respond to these injuries at the cellular and molecular levels, and in their brain repair and recovery processes. Also, the patterns of cerebrovascular dysfunction and stroke vulnerability after TBI are different in males and females based on animal studies.