Aging, the immune response, and traumatic brain injury

Aging is a natural process that has a large impact on health, including a process termed immunosenescence. Immunosenescence modifies the efficiency of the immune system and alters the inflammatory status of the brain. People aged over 65years are at a high risk of sustaining a traumatic brain injury (TBI), and this population has higher mortality and hospitalization rates after TBI compared to their younger counterparts. An immune response is one of the most influential pathophysiological mechanisms that occurs in TBI. Therefore, it stands to reason that the altered immune response as a result of aging could impact TBI pathology and contribute to worse outcomes. Aging also involves deterioration of other biological systems that are directly or indirectly linked to immunosenescence and can also have an impact on TBI outcomes. This chapter will outline the current understanding of the intersection between aging and the immune response in the context of TBI.