The effects of pediatric traumatic brain injury on verbal and visual-spatial working memory.

The purpose of this study was to investigate the effects of pediatric traumatic brain injury (TBI) on verbal and visual-spatial working memory (WM). WM tasks examined memory span through recall of the last item of a series of stimuli. Additionally, both verbal and visual-spatial tests had a dual-task condition assessing the effect of increasing demands on the central executive (CE). Inhibitory control processes in verbal WM were examined through intrusion errors. The TBI group (n = 73) performed more poorly on verbal and visual-spatial WM tasks than orthopedic-injured children (n = 30) and non-injured children (n = 40). All groups performed more poorly on the dual-task conditions, reflecting an effect of increasing CE load. This effect was not greater for the TBI group. There were no group differences in intrusion errors on the verbal WM task, suggesting that problems in WM experienced by children with TBI were not primarily due to difficulties in inhibitory control. Finally, injury-related characteristics, namely days to follow commands, accounted for significant variance in WM performance, after controlling for relevant demographic variables. Findings suggest that WM impairments in TBI are general rather than modality-specific and that severity indices measured over time are better predictors of WM performance than those taken at a single time point.