| Traumatic brain injury (TBI) is the most common cause of death and acquired brain insult in American children, and therefore a major public health concern. Children less than one year of age are disproportionately likely to sustain a TBI, but this age group has been relatively neglected in the TBI research literature. In young school-age children, significant age-at-injury effects have been found in that children injured at younger ages tend to have worse outcome. This is in contrast to the predicted pattern of neuroplasticity, with younger brains tending to demonstrate greater plasticity. Additionally, studies of children after TBI reveal significant impact on control of attention, working memory, planning, and inhibitory control (executive functions (EF).) These areas often remain persistently compromised, even when overall cognitive functioning shows good recovery. Little is known about how the early components of EF may be affected when TBI occurs in infancy. The current study examined the relationship between injury variables (severity and age-at-injury) and cognitive and executive functioning in 15-month-old children following TBI sustained prior to one year of age. Nineteen children who sustained a TBI and 15 uninjured children were tested at 15 months of age. Cognitive functioning was measured with the Mental Scale of the Bayley-II. Working memory and inhibitory control were measured with a manual delayed response task (A-Not-B.) In the current study, children with TBI performed worse on average than uninjured children in overall cognitive functioning and executive functioning. Earlier age-at-injury was associated with poorer cognitive functioning at all severity levels. Earlier age-at-injury was associated with poorer EF performance in children with milder injuries, but not in those with more severe injuries. Results of the current study also support the use of an early "marker" task (the A-Not-B delayed response task) that appears sensitive to impairments in early components of executive functioning. The current study adds to the small body of knowledge about outcome after TBI in infancy and provides a strong case for routine neurodevelopmental follow-up as the standard of care for these children. |
