Effects of aging on blood brain barrier and matrix metalloproteases following controlled cortical impact in mice

► Blood brain barrier disruption after traumic brain injury is greater in aged than adult mice. ► Activation of MMP-9 after traumatic brain injury is greater in aged than adult mice. ► Expression of the blood brain barrier structural protein claudin-5 is impaired after traumatic brain injury in aged mice. ► Increased blood brain barrier disruption and decreased repair may contribute to poor outcomes after injury to the aged brain.