H2AX and Anxiety: Subjecting young (12-week-old) and aged (18-month-old) male C57BL/6 mice to controlled cortical impact (CCI) results in more severe deficits in forelimb grip strength, balance, motor coordination, spontaneous locomotor activity, and anxiety-like behavior in the aged group. Aged mice showed higher number of peripheral leukocyte infiltration post-TBI. Microglia of aged mice showed significantly higher senescent markers (BCL-2, p16Ink4a, p21Cip1/Waf1, and H2AX) at baseline and after CCI, associated with impairment in phagocytosis and higher IL-1β production (Ritzel et al., 2019).