ABSTRACT
While no firm consensus has been achieved, it is generally agreed that the term executive function (EF) refers to a set of skills, which are necessary for independent, purposeful, goal-directed activity (Lezak, 1995; Stuss & Benson, 1986). Historically, frontal structures, and in particular prefrontal cortices, have been considered to play an integral role in subserving and coordinating executive abilities (Benton, 1991; Damasio, Grabowski, Frank, Galaburda, & Damasio, 1994: Stuss & Alexander, 2000). These cerebral regions are relatively immature during childhood, with development thought to be a protracted process, which continues into early adolescence at least (Barnea-Goraly et al., 2005; Giedd et al., 1999; Gogtay et al., 2004; Sowell et al., 2003;Yakovlev&Lecours, 1967). Parallels between ongoing maturation of the frontal lobes and the emergence of executive capacities have been reported in a number of studies. These results suggest that, where developmentally appropriate behavioral assessment tools are employed, evidence of EF can be reliably elicited in children as young as age three (Anderson & Lajoie, 1996; Diamond, 2002; Espy, 2004; Passler, Isaac, & Hynd, 1985; Smidt, Jacobs, & Anderson, 2004; Welsh, Pennington, & Groisser, 1991; Zelazo, Craik, & Booth, 2004). It is now well established that children suffering from both developmental and
acquired disorders, and disease of the central nervous system (CNS) are at risk of experiencing executive impairments, or dysexecutive syndrome. Such problems may
interfere with the child’s capacity to develop normally and interact effectively with the environment, thus leading to ongoing cognitive, academic, and social disturbances (Anderson & Catroppa, 2005; De Luca et al., 2003; Dennis, 1989; Levin & Hanten, 2005). Individual case studies provide anecdotal evidence of problems in planning, problem solving, and abstract thinking in the day-to-day lives of these children (Anderson, 1988; Eslinger, Flaherty-Craig, & Benton, 2004; Mateer & Williams, 1991), however such ‘executive dysfunction’ is often difficult to detect using traditional assessment tools. Further evidence comes from a handful of recent studies, which have examined EF following childhood brain injuries. Findings suggest that residual deficits in planning, problem solving, and adaptive behavior are associated with traumatic brain injury (Anderson & Catroppa, 2005; Asarnow, Satz, Light, Lewis, & Neumann, 1991; Ewing-Cobbs, Prasad, Landry, Kramer, & DeLeon, 2004; Levin & Hanten, 2005; Pentland, Todd, & Anderson, 1998), hydrocephalus and spina bifida (Jacobs, Northam, & Anderson, 2001; Landry, Jordan, & Fletcher, 1994), and cranial irradiation for treatment of childhood cancers (Anderson, Godber, Smibert, Weiskop, & Ekert, 2004; Brouwers, Riccardi, Poplack, & Fedio, 1984; Stehbens et al., 1991). However, accurate and reliable identification of such deficits, both in clinical practice and research endeavors, continue to be a challenge due to a scarcity of developmentally appropriate assessment tools, and the common use of outcome parameters that are not uniquely specific to EF. This chapter aims to review evidence on the development of EF. Consistent with
contemporary developmental neuroscience approaches, three dimensions will be considered: psychological, biological, and developmental. A second objective is to consider methods of assessment of EF relevant to pediatric practice, and their strengths and weaknesses.
