This study investigated dimensions of executive functioning in 8- to 13-year-old children. Three tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB), two tasks from the NEPSY battery and some additional executive function (EF) tests were administered to 108 children. In line with earlier work, modest correlations among EF measures were obtained (r < .4). Both exploratory and confirmatory factor analyses yielded three interrelated factors, which resembled those obtained by Miyake et al. (2000) and which were—with some reservations—labelled Working Memory (WM), Inhibition and Shifting. Age correlated with performance on most individual EF measures as well as Shifting and WM. The present findings are in agreement with contemporary views as to the simultaneous unity and diversity of EFs.

Dimensions of executive functioning: Evidence from children

A brief review of the literature reveals that many psychologists believe that certain tests measure frontal lobe deficits. However, recent carefully controlled studies suggest that neuropsychological deficits are far from specific for frontal versus nonfrontal lesions. In this study, we compared groups with frontal and nonfrontal cerebral lesions that were approximately equivalent for types of lesions and other variables. No intergroup differences were found on the Category Test and Part B of the Trail Making Test. The results suggest that neuropsychologists should adopt a more critical attitude concerning so-called “frontal lobe deficits.”

Category test and trail making test as measures of frontal lobe functions

Recent studies indicate that in several regions of the world, arsenic concentration in water is much higher than accepted levels (Smedley and Kinniburgh 2002). The concern with As contamination of drinking water is that consumption and use of this water in cooking can increase As exposure in humans (Del Razo et al. 2002). In Mexico, the amount of this contaminant in ground water varies from 10 to 5,000 μg/L (Del Razo et al. 1990). Del Razo et al. (1990; 1994) reported on the problem of As-contaminated groundwater in the Lagunera Region of northern Mexico, with > 50% of samples having As concentrations > 50 μg/L, which was the former level of reference set by the World Health Organization (International Programme on Chemical Safety 2001). The predominant type of As in 90% of the samples was pentavalent arsenic.

In 1977, the presence of As in potable water was reported in the city of Torreon, the main city in the Region Lagunera and the site of the most important metallurgic complex of Mexico. As concentration in Torreon’s water was up to 4–6 mg/L, far above the present 10-μg/L limit (Cebrian et al. 1994; Mandal and Suzuki 2002). Benin et al. (1999) evaluated heavy metal contamination of soil in three residential areas that surround the smelter and found that As levels had a median of 113 μg/g, and ranged from 78 to 287 μg/g. These levels exceeded the level at which the U.S. Environmental Protection Agency (EPA) designated cleanup goals for Superfund sites, 5–65 μg/g (U.S. EPA 1997).

Approximately 60–90% of the soluble inorganic arsenic (InAs) components are absorbed through the gastrointestinal tract (Hall 2002). In humans, InAs metabolism involves at least five metabolites that can exert toxic effects (Valenzuela et al. 2005). The measure of urinary As (UAs) excretion is a good biomarker for chronic exposure via drinking water [Agency for Toxic Substances and Disease Registry (ATSDR) 2000]. As concentration in urine, normally < 10 μg/L, can reach as high as 50 μg/L in adults and children living close to metal foundries (Carrizales et al. 2006; Polissar et al. 1990).

The negative consequences of As exposure in humans include respiratory, gastrointestinal, hematologic, hepatic, renal, dermic, neurologic, and immunologic effects (ASTDR 2000; Garcia-Vargas and Hernandez-Zavala 1996; International Programme on Chemical Safety 2001), many of which continue even after the contaminant source is controlled (Diaz-Barriga et al. 1997). As can also have detrimental effects on the central nervous system and cognitive development in children (International Programme on Chemical Safety 2001). Acute As exposure affects sensory nerves as well as the long axon neurons, which results in the clinical manifestation of numb extremities. Neurologic tests have shown nerve axonophathy and demyelination (Franzblau and Lilis 1989; Rodriguez et al. 2003; Yung 1984). As also affects the content of brain monoamines, and the concentrations of dopamine and serotonin in the hippocampus, hypothalamus, cerebral cortex, and the striatum (Itoh et al. 1990; Mejia et al. 1997; Rodriguez et al. 2003).

Few reports have suggested a detrimental effect of As exposure on cognitive development and function, including disturbed visual perception, problems with visuomotor integration, psychomotor speed, attention, speech, and memory. (Calderon et al. 2001; Rodriguez et al. 2003; Tsai et al. 2003). In this regard, the effects of As are similar to and could be confounded with the effects of other environmental contaminants such as lead. In fact, in many regions of the world, As exposure co-occurs with exposure to other contaminants such as lead (Carrizales et al. 2006; Diawara et al. 2006). Poorer performance on a range of cognitive tests has been reported in children with low to moderate lead exposure in Torreon (Kordas et al. 2004) and other settings (Canfield et al. 2003; De Burbure 2006; Lanphear et al. 2000).

In this study we identified demographic and nutritional factors that are associated with UAs concentration in school-age children. We also investigated the influence of As exposure on cognitive function in these children.

Arsenic Exposure and Cognitive Performance in Mexican Schoolchildren

There is little data available concerning the executive functions of children with dyslexia. The small number of existing studies in this field focus on single aspects of these functions such as working memory. The aim of the present study was therefore to assess a variety of aspects of executive functioning in children with dyslexia. Forty-two children with dyslexia and 42 non-dyslexic children were examined using a neuropsychological test battery. The test battery consisted of standardised tests examining the assessment of working memory, concept formation, inhibition, flexibility, problem solving and fluency functions. Comparison between the test performance of non-dyslexic children and children with dyslexia revealed obvious difficulties of children with dyslexia in tests measuring working memory. Inhibition of inappropriate reactions was impaired in children with dyslexia in more demanding tests, but not in simple ones. Furthermore, children with dyslexia displayed impairments of both verbal and figural fluency functions. While in comparison to non-dyslexic children no disturbances of concept formation were observed, problem solving seemed to be partially impaired. The present findings suggest that children with dyslexia demonstrate impairments in a variety of executive functions. This should be considered in the development of new concepts in the treatment of dyslexia.

Executive functions in children with dyslexia.

This article addresses the need for age-relevant outcome measures for traumatic brain injury (TBI) research and summarizes the recommendations by the inter-agency Pediatric TBI Outcomes Workgroup. The Pediatric Workgroup's recommendations address primary clinical research objectives including characterizing course of recovery from TBI, prediction of later outcome, measurement of treatment effects, and comparison of outcomes across studies. Consistent with other Common Data Elements (CDE) Workgroups, the Pediatric TBI Outcomes Workgroup adopted the standard three-tier system in its selection of measures. In the first tier, core measures included valid, robust, and widely applicable outcome measures with proven utility in pediatric TBI from each identified domain including academics, adaptive and daily living skills, family and environment, global outcome, health-related quality of life, infant and toddler measures, language and communication, neuropsychological impairment, physical functioning, ps...

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D. A. Sena

Papers

Neuropsychological Evaluation of Older Children

Neuropsychological Evaluation of Older Children: By Ralph M. Reitan and Deborah Wolfson, South Tucson, AZ: Neuropsychology Press, 1992. + 814 pp

A comparison of subject characteristics for a matched sample of cognitive retraining patients with nontreatment patients