Executive function profiles in pediatric traumatic brain injury
Creators: name: Ringdahl, Erik Nelson
Publisher: name: University of Nevada, Las Vegas
Year: 2011

description: Traumatic brain injury is a common cause of disability and death among children in the United States. Insult to the frontal and temporal lobes are frequent in closed head brain injury. Cognitive deficits in a variety of domains are common sequelae of brain trauma. In many cases, trauma to the frontal and temporal lobe regions engender prominent deficits in higher-order cognitive processing, memory, and attention. 
Higher-order cognitive processing, or Executive Functions are the grouping of cognitive processes necessary for organization of thoughts and activities, attending to the activities, prioritizing tasks, managing time efficiently, and making decisions (Alvarez & Emory, 2006; Jurado & Rosselli, 2007; Miyake et al., 2000). Due to the complexity and heterogeneity of the executive functioning construct, researchers often conceptualize the multiple functions into executive subprocesses (Alvarez & Emory, 2006; Goldberg et al., 2003; Goldberg & Weinberger, 2004; Jurado & Rosselli, 2007; Miyake et al., 2000; Stuss & Alexander, 2000; Zelazo et al., 1997) including, but not limited to shifting, updating, inhibition, cognitive flexibility, problem-solving, response maintenance, goal-formation, planning, task-analysis, and even working memory. Despite the importance of the frontal lobes in regulating cognitive abilities, many of their functions are still not well understood. 
Examination of specific executive subprocesses between healthy individuals and those who have sustained a traumatic brain injury (TBI) would provide insight into the function of executive subprocesses, how they manifest in healthy controls, and importantly, how they are disturbed by brain injury. Notwithstanding, identifying the neurocognitive profiles associated with certain executive subprocesses may better help medical professionals to classify and treat subtypes of childhood TBI. 
Tasks that assess executive subprocesses have existed for many years, with one of the oldest and most well studied task being the Trail Making Test (TMT; Reitan, 1986; Reitan & Wolfson, 1993; U.S. Army Individual Test Battery, 1944). The Trail Making Test assesses different aspects of executive functioning including, scanning, visuo-motor, spatial skills, tracking, planning, shifting, divided attention, inhibition, and cognitive flexibility ability. With over 60-years of use, the psychometric properties of the TMT have been well established, and it has been shown to be sensitive to both acquired and neurodevelopmental forms of brain damage (Moll, Oliveira-Souza, Moll, Bramati, & Andreiuolo, 2002; Reitan, 1955; Reynolds, 2002; Wiegner & Donders, 1999; Sánchez- Cubillo et al., 2009; Zakzanis, Mraz, & Graham, 2005). While sensitive to the biological integrity of the frontal lobes, tasks such as the TMT also appear sensitive to lesions in other brain regions (Demakis, 2004; Stuss, et al., 2001). 
In recent years, a number of alternate versions of the TMT have been developed, with one notable example being the Comprehensive Trail Making Test (CTMT; Reynolds 2002). The CTMT was designed to provide an expanded assessment of the executive functions assessed by its predecessor, and is purported to assess decision-making, planning, inhibition, sequencing, development of actions, and motor outputs. Like theTMT, initial validity evidence supports the sensitivity of the CTMT to brain injury (Allen, Haderlie, Kazakov, & Mayfield, 2009; Armstrong, Allen, Donohue, & Mayfield, 2007; Orem, Petrac, & Bedwell, 2008). In addition, the CTMT provides norms based on a large standardization sample (N = 1769) ranging in age from 8 to 89-years of age, that is stratified by age, gender, ethnicity, and geographic region. In order to be representative of the United States population, CTMT norms are based on the 2000 census data. 
Based on these considerations, the current study will investigate executive subprocess performance as assessed by the Comprehensive Trail Making Test (CTMT) in 242 children and adolescents, including 121 with TBI, and 121 matched normal controls. The present study will use cluster analysis of CTMT scores to determine whether 1) discrete executive function subgroups of children with TBI can be identified and 2) whether these TBI subgroups differ in executive function profiles from normal children. Results are anticipated to advance understanding of TBI heterogeneity in executive function ability, as assessed by the CTMT. It is also hoped that results from this study provide insight into higher-order cognitive processing in children, such that results may assist in short- and long-term treatment of childhood TBI.