A Review of Traumatic Brain Injury Animal Models: Are We Lacking Adequate Models Replicating Chronic Traumatic Encephalopathy?

Traumatic brain injury (TBI) continues to be a significant problem affecting many individuals on a daily basis. There are various subtypes of traumatic brain injuries ranging from life-threatening cerebral edema to the injuries not accounted for by current radiographic imaging. To understand the pathological features of TBI and evaluate potential therapeutic strategies for TBI, various animal models have been created and characterized. Each of the animal models is aimed to mimic a certain type of clinical TBI. In this review article, we critically evaluate the various types of animal models for TBI, and describe which patient populations these models are intended to represent. Mild traumatic brain injury bears the highest representation of TBI in the United States. Chronic traumatic encephalopathy (CTE) is the longterm sequelae of such recurrent mild brain injuries. We particularly emphasize the animal model for CTE in this article because research in this arena tends to significantly lag behind societal awareness of this ever-growing problem amongst our nation's athletes. Repetitive traumatic brain injuries in humans have the potential to cause significant neurobehavioral and psychiatric disturbances years after the inciting events, as the injuries accumulate over time. Postmortem examination of brains from the patients who experienced repetitive traumatic brain injuries displays pathological profiles of CTE. Creating animal models for CTE have only just begun. The models that culminate in the animal-equivalent of CTE in humans remain to be developed in future studies.