Secondary insults post traumatic brain injury (TBI) entails a deadly disease process, with impaired cerebrovascular reactivity dominating the landscape of cerebral physiologic insult burden during the acute phase post-injury. Age and biological sex are potential modifiers of this process. Through this thesis, age and biological sex subgroup differences and impacts on insult burden of cerebral physiology was investigated, with the hypotheses that advancing age, and not sex, would be associated with worse cerebrovascular function post-TBI. Two separate cohorts of TBI patients were evaluated, totalling 42 males, 7 females and 224 males, 59 females, respectively. The following measures of cerebrovascular reactivity were studied: Pressure reactivity index (PRx), pulse amplitude index (PAx) and RAC. Statistically significant results were found where impaired cerebrovascular reactivity (PAx and RAC not PRx) was seen with advancing age but unclear results with sex. These interesting findings require further investigation to ascertain the true utility of these indices in neurotrauma care.