Recovery of Working Memory Following Pediatric Traumatic Brain Injury: A Longitudinal Analysis

The purpose of this dissertation was to investigate the developmental trajectories of verbal and visual-spatial WM in children following traumatic brain injury, and to determine how age at injury and injury severity affects growth. As part of a larger assessment, the sample included 42 children with severe head injury, 13 children with complicated mild-moderate head injury, and 47 children with orthopedic injury. Longitudinal data was collected at 2, 6, 12 and 24 months post-injury. A multivariate approach to individual growth curve modeling was utilized and the data was centered at 12 months post-injury. Results indicated that at 12 months post-injury, children in all three injury groups with varying age at injury did not differ significantly on verbal or visual-spatial working memory performance. The injury groups did not differ on working memory performance when age at injury was held constant. A significant rate of change (slope) by age at injury by injury group interaction for verbal working memory (and a similar pattern for visual-spatial working memory) revealed that children injured at a younger age with more severe injuries demonstrated the slowest working memory growth, but that as age at injury increased, older children with severe injuries exhibited faster growth. A significant positive relation was found between level of performance on verbal and visual-spatial working memory tasks at 12 months post-injury, but not for rate of growth. This study lends further support to an early vulnerability hypothesis, which suggests that children brain-injured at a younger age are more vulnerable to cognitive deficits.