Memory and Attention Profiles in Pediatric Traumatic Brain Injury

Archives of Clinical Neuropsychology 25 (2010) 618–633 Memory and Attention Profiles in Pediatric Traumatic Brain Injury Daniel N. Allen 1,*, Brian D. Leany 1, Nicholas S. Thaler 1, Chad Cross 2, Griffin P. Sutton 1, Joan Mayfield 3 1 2 Department of Psychology, University of Nevada, Las Vegas, NV, USA Department of Environmental and Occupational Health, Epidemiology and Biostatistics Unit, University of Nevada, Las Vegas, NV, USA 3 Our Children’s House at Baylor, Dallas, TX, USA *Corresponding author at: Neuropsychology Research Program, Department of Psychology, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154, USA. Tel.: +1-702-895-1379; fax: +1-702-895-0195. E-mail address: (D.N. Allen). Accepted 16 June 2010 Abstract 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. Keywords: Attention; Childhood brain insult; Head injury; Traumatic brain; Injury; Learning and Memory Introduction Behavioral disturbances and neurocognitive deficits in attention, learning, and memory commonly occur following traumatic brain injury (TBI; Babikian & Asarnow, 2009; Roman et al., 1998; Schwartz, et al., 2003; Yeates et al., 2005). These neurocognitive deficits are associated with a number of important outcomes (Gil, 2003; Rassovsky et al., 2006). However, both the severity and patterns of neurocognitive impairment are heterogeneous. Heterogeneity of these neurocognitive and behavioral deficiencies are not reflected in more general approaches to TBI severity classification based on, for example, open and closed head injury, length of coma or post-traumatic amnesia, and persisting neurological signs (Reitan & Wolfson, 1993), and it may be that neurocognitive tests could provide more meaningful classification by identifying subgroups of children with TBI, who differ not only in the patterns of neurocognitive deficits, but also exhibit differences in other domains, such as behavioral abnormalities, academic achievement, and functional outcomes. Cluster analysis has been effectively used to identify subgroups of patients who exhibit differing patterns of neurocognitive impairment in a variety of psychiatric and neurological disorders, including TBI (Allen et al., 2000; Crawford, Garthwaite, & Johnson, 1997; Demery, Pedraza, & Hanlon, 2002; Wiegner & Donders, 1999). Studies of adults with TBI indicate the existence of discrete TBI subgroups that differ with regard to both pattern and severity of neurocognitive deficits (Chan, Hoosain, Lee, Fan, & Fong, 2003; Crosson, Greene, Roth, Farr, & Adams, 1990; Goldstein, Allen, & Caponigro, 2010; Malec, Machulda, # The Author 2010. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: . doi:10.1093/arclin/acq051 Advance Access publication on 28 July 2010 D.N. Allen et al. / Archives of Clinical Neuropsychology 25 (2010) 618–633 619 & Smigielski, 1993; Millis & Ricker, 1994; van der Heijden & Donders, 2003). Fewer studies have examined neurocognitive heterogeneity in children with TBI, but provide evidence for similar heterogeneity as observed in adults, when the California Verbal Learning Test for Children and the Wechsler Intelligence Scale for Children are examined (Donders & Warschausky, 1997; Mottram & Donders, 2006). Although providing substantive support for the presence of neurocognitive heterogeneity in TBI, the results of these studies are limited in a number of ways, including in some cases, the use of small sample size which limits generalizability, the use of IQ tests to develop clusters, because IQ tests have limited sensitivity to brain damage (Malec et al., 1993), and the relative absence of support for the “external validity” of cluster solutions through, for example, examination of cluster differences on neurocognitive, achievement, or behavioral variables that were not included in the cluster analysis. With regard to this latter point, associations between cluster membership and post-injury disability in TBI (Malec et al. 1993), as well as differences in neurocognitive abilities and affective symptomotology in HIV infected individuals (Murji et al., 2003), provide some evidence that neurocognitive subtypes may have utility in predicting post-injury disability, psychiatric status, and possibly other outcomes in pediatric TBI. A further limitation is that there has not been a direct comparison between clusters derived in TBI and nonbrain injured samples in order to establish whether TBI results in different profiles, even though the importance of such comparisons has been noted for many years (Crosson et al., 1990). Separate cluster analysis of TBI and standardization sample (SS) data for measures such as the CVLT and Wechsler Intelligence scales (Donders, 1996, 1999, 2008; Donders, Zhu, & Tulsky, 2001) provide support for such differences, but direct comparisons between the groups are made difficult due to differences among the TBI and normal groups in sample size, demographic variables, as well as other considerations. Additionally, there has been a tendency for cluster analytic studies to focus on a single ability (e.g., verbal memory), which constrains the identification of clusters that might reflect meaningful subtypes within TBI, because TBI may result in a variety of neurocognitive deficits. Finally, in some studies, cluster analysis is used to investigate the psychometric properties of specific tests by, for example, determining base rates of score profiles for a particular instrumen (...truncated)