Rani Jacobs

Development of Executive Functions Through Late Childhood and Adolescence in an Australian Sample

Although there have been significant theoretical advances in the field of child neuropsychology, developmental features of adolescence have received less attention. Progress in clinical practice is restricted due to a lack of well-standardized, developmentally appropriate assessment techniques. This article addresses these issues in relation to executive skills. These abilities are targeted for 2 reasons: first, because they are often considered to be mature during late childhood and adolescence, despite limited investigation in this age range; and second, because of their central importance to efficient day-to-day functioning. Using a normative sample of 138 children, aged 11.0 to 17.11 years, this article plots the development of executive skills through late childhood and early adolescence and interprets progress in these skills with reference to current neurological and cognitive theory.

Relationships between cognitive and behavioral measures of executive function in children with brain disease.

This study addressed the clinical and construct validity of the Behavior Rating Inventory of Executive Function. (BRIEF: Gioia, Isquith, Guy, & Kenworthy, 2000), a questionnaire designed to tap behavioral aspects of executive functions in children. BRIEF profiles in early treated phenylketonuria (PKU; n = 44), early treated hydrocephalus (n = 45), frontal focal lesions (n = 20) and controls (n = 80) were examined. Clinical validity was supported through significant between-group comparisons, especially between the frontal focal lesion group and other groups. To examine construct validity, raw scores on cognitive executive function measures including the Contingency Naming Test (CNT), Rey Complex Figure (RCF), Tower of London (TOL), and Controlled Oral Word Association Test (COWAT), were correlated with BRIEF scale scores. Few significant correlations were found, indicating cognitive and behavioral measures appear to tap different constructs within the executive function domain. A dissociation was found between behavioral and cognitive impairments in the frontal as opposed to PKU and hydrocephalus groups. This is discussed in relation to underlying pathology, the cognitive measures used, and possible limitations in the BRIEFs usefulness for measuring behavioral executive dysfunction in groups only mildly affected by neurological compromise.

Childhood brain insult: can age at insult help us predict outcome?

Until recently, the impact of early brain insult (EBI) has been considered to be less significant than for later brain injuries, consistent with the notion that the young brain is more flexible and able to reorganize in the context of brain insult. This study aimed to evaluate this notion by comparing cognitive and behavioural outcomes for children sustaining EBI at different times from gestation to late childhood. Children with focal brain insults were categorized according to timing of brain insult, represented by six developmental periods: (i) Congenital (n = 38): EBI: first-second trimester; (ii) Perinatal (n = 33); EBI: third trimester to 1 month post-natal; (iii) Infancy (n = 23): EBI: 2 months-2 years post-birth; (iv) Preschool (n = 19): EBI: 3-6 years; (v) Middle Childhood (n = 31): EBI: 7-9 years; and (vi) Late Childhood (n = 19): EBI: after age 10. Groups were similar with respect to injury and demographic factors. Children were assessed for intelligence, academic ability, everyday executive function and behaviour. Results showed that children with EBI were at increased risk for impairment in all domains assessed. Furthermore, children sustaining EBI before age 2 years recorded global and significant cognitive deficits, while children with later EBI performed closer to normal expectations, suggesting a linear association between age at insult and outcome. In contrast, for behaviour, children with EBI from 7 to 9 years performed worse than those with EBI from 3 to 6 years, and more like those with younger insults, suggesting that not all functions share the same pattern of vulnerability with respect to age at insult.

The object classification task for children: A new measure of concept generation and mental flexibility in early childhood

In this study, the development of concept generation and mental flexibility was investigated in 84 Australian children between 3 and 7 years of age, using the Object Classification Task for Children (OCTC), a newly developed executive function test for use with young children. On this task, which was adapted from the Concept Generation Test (Levine, Stuss, & Milberg, 1995) and the Concept Generation Test for Children (Jacobs, Anderson, & Harvey, 2001), children were asked to categorize 6 plastic toys according to 3 predetermined groupings (i.e., color, size, and function). The test included 3 performance levels, each providing increasing levels of structure for the child. Findings from the OCTC show meaningful age-related changes in performance across age groups, with older children being less dependent on additional structure to complete the task, in comparison to younger children. Furthermore, findings from this study suggest that the ability to generate concepts emerges between 3 and 4 years of age, continuing to develop beyond the age of 7 years. A developmental spurt in cognitive flexibility was observed around 4 to 5 years of age, with refinement of this capacity occurring between 5 and 7 years of age. Results suggest that the OCTC is a useful measure of conceptual reasoning skills in early childhood.

Does Early Age at Brain Insult Predict Worse Outcome? Neuropsychological Implications

OBJECTIVE Traditionally early brain insult (EBI) has been argued to have better outcome than later injury, consistent with the notion that the young brain is flexible and able to reorganize. This view was investigated by comparing neurobehavioral outcomes of children sustaining EBI at different developmental stages (gestation to late childhood). METHODS One hundred and sixty four children who had sustained focal brain insult (confirmed by MRI) formed six groups, based on age at EBI, (a) Congenital; (b) Peri-natal; (c) Infancy; (d) Preschool; (e) Middle Childhood; (f) Late Childhood, and were compared on a range of standardized neurobehavioral measures. Groups were matched for lesion characteristics and demographics. RESULTS Children sustaining EBI before age 2 recorded global deficits, while children with later EBI performed closer to average. CONCLUSION These results question the advantages of early brain plasticity, demonstrating poorer outcome from very early insults, and increasingly better function with lesions later in childhood.

Planning and problem solving skills following focal frontal brain lesions in childhood: analysis using the Tower of London.

Problem solving skills were investigated in children with focal lesions using the Tower of London test (TOL; Shallice, 1982). The scoring procedure was elaborated from previous studies to delineate separate processes contributing to overall performance in children. Thirty-one children with focal frontal pathology, 18 children with focal pathology in other brain regions (extra-frontal), 17 children with generalized pathology and 38 healthy children participated in the study. Results suggest a distributed network for problem solving skills, particularly cognitive flexibility and goal setting skills. Within the frontal group, children with lesions involving the right pre-frontal cortex had greatest problems with self-regulation, with rule breaks most common among this group. As these skills develop relatively early in comparison to other aspects of executive function, right pre-frontal regions may play a particularly important role in the development of executive skills in childhood, with damage to these regions rendering children vulnerable to a range of cognitive and social deficits.

Cognitive Outcome in Children With Myelomeningocele and Perinatal Hydrocephalus: A Longitudinal Perspective

Myelomeningocele, a form of spina bifida where the vertebrae fail to fuse during foetal development, is often associated with sensory deficits, reduced motor function and hydrocephalus. These complications may interfere with the development of the central nervous system affecting myelination of axons and formation of synaptic connections, and development of cognitive skills, particularly where complications occur within the first twelve months of life. This paper examines the long-term cognitive outcome in nineteen children with myelomeningocele, who were shunted for hydrocephalus within the first year of life. In comparison to a healthy control group matched for age and gender, the clinical sample were found to have globally compromised cognitive skills, including reduced intellectual and educational skills. Specific impairments were noted on measures of speed of processing, immediate registration of information, learning and memory, organisation and high level language, with greatest deficits on more complex, less structured tasks. Within the clinical group, there was a fall in IQ over time, suggesting a failure to acquire cognitive skills in the expected time frame. These results, reflecting a cumulative pattern of deficits over time, highlight the importance of long-term follow up in children with myelomeningocele and perinatal hydrocephalus.

Executive Function Following Child Stroke: The Impact of Lesion Size

Childhood stroke is increasingly recognized as a major cause of childhood morbidity and mortality; however, limited information exists regarding neurobehavioral sequelae. Executive function (EF), important for problem solving, reasoning, social awareness, and adaptive behavior, may be particularly vulnerable to early brain lesions such as stroke, due to its protracted development. This study investigated: (i) the impact of childhood stroke on EF; and (ii) the impact of lesion size on EF outcome. Twenty-eight children diagnosed with stroke at least 12 months prior to assessment were recruited. Neurobehavioral assessment focused on cognitive and behavioral aspects of EF. Lesion volume was determined from standard ratings of brain pathology based on magnetic resonance imaging (MRI) scans. Deficits in cognitive aspects of EF were detected in attentional control, cognitive flexibility and information processing. Difficulties in behavioral aspects of EF were most striking, with problems identified across a wide range of behaviors. Lesion size impacted on EF, with large lesions (greater than 25% of brain volume) proving the most detrimental.

Are executive skills primarily mediated by the prefrontal cortex in childhood? Examination of focal brain lesions in childhood.

INTRODUCTION Based on the study of adults with brain insult, traditional localizationist views have argued that executive skills are primarily mediated by prefrontal cortex. It remains unclear whether a similar pattern of localization exists in childhood. METHODS To investigate this hypothesis, we compared the performance of children, aged 7-16 years, with radiological evidence of brain pathology. The sample was divided according to lesion location as follows: frontal pathology (n=38), extra-frontal pathology (n=20), generalized pathology (n=21) and healthy controls (n=40). Using a multidimensional model of executive function described by Anderson (2002) and Anderson (1998; Anderson et al., 2001c, 2001d), these groups were compared on a range of executive function domains including: attentional control, goal setting, cognitive flexibility, and information processing. Additional, non-executive measures were also administered. RESULTS Contrary to adult lesion-based studies, there was little differentiation in executive processes between frontal and extra-frontal groups. CONCLUSIONS These results provide support for contemporary models which propose a distributed, but integrated neural network for executive skills, suggesting that the integrity of the entire brain is necessary for adequate executive functions in childhood. Further, focal lesions to any brain region during development may render children vulnerable to a range of executive deficits that would not normally be expected following similar pathology in adulthood.

Executive Function Following Child Stroke: The Impact of Lesion Location

Child stroke is a major cause of death in children, although limited information exists on neurobehavioral functioning of stroke survivors. Executive function (important for goal-directed behavior) is thought to be vulnerable to early insults such as stroke because of its widespread representation in the immature brain. This study investigated the impact of lesion location on executive skills. Twenty-eight children diagnosed with stroke at least 18 months before assessment were recruited. Lesion characteristics were coded from magnetic resonance imaging (MRI) scans. Neurobehavioral assessment focused on cognitive and everyday executive skills. Deficits were found in the context of overall normal intellectual functioning (M = 91.60; SD = 19.40). Generally, insults involving frontal and extra-frontal regions impacted equally on cognitive performance. Everyday deficits were marginally more prominent following frontal insult. Subcortical frontal lesions were associated with impairments in everyday executive skills. Results provide further support for the diffuse representation of executive function in the immature brain.