Memory and attention profiles in pediatric traumatic brain injury

Traumatic brain injury (TBI) causes heterogeneous patterns of neurocognitive deficits. In an attempt to identify homogenous subgroups within this heterogeneity, cluster analysis was used to examine memory and attention abilities as measured by the Test of Memory and Learning (TOMAL) in 300 children, 150 with TBI and 150 matched nonbrain injured controls (standardization sample [SS]). Significant differences were present between the TBI and the SS groups on all TOMAL subscale and index scores, with the TBI groups performing approximately 1.3 SD below the SS. Factor analysis of the TOMAL indicated six factors that assessed various aspects of verbal and nonverbal learning and memory, as well as attention/concentration. Cluster analyses of TOMAL factor scores indicated that a four-cluster solution was optimal for the SS group, and a five-cluster solution for the TBI group. For the TBI clusters, differences were present for clinical, achievement, neurocognitive, and behavioral variables, providing some support for the validity of the cluster solution. These findings suggest that TBI results in unique patterns of neurocognitive impairment that are not accounted for by individual differences in test performance commonly observed in normal populations. Additionally, neurocognitive profiles identified using cluster analysis may prove useful for identifying homogeneous subgroups of children with TBI that are differentiated by a number of important clinical, cognitive, and behavioral variables associated with treatment and outcomes.