Changes in working memory after traumatic brain injury in children

The impact of traumatic brain injury (TBI) on working memory (WM) was studied in 144 children (79 with mild, 23 with moderate, and 42 with severe injuries) who underwent magnetic resonance imaging (MRI) at 3 months and were tested at baseline and at 3, 6, 12, and 24 months postinjury. An n-back WM task for letter identity was administered with memory load ranging from 1- to 3-back and a 0-back condition. A TBI Severity X Quadratic Time interaction showed that net percentage correct (correct detections of targets minus false alarms) was significantly lower in severe than in mild TBI groups. The Left Frontal Lesions X Age interaction approached significance. Mechanisms mediating late decline in WM and the effects of left frontal lesions are discussed.