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Background: The most common route for general population exposure to methyl mercury (MeHg) is fish consumption. Recommendations to pregnant women about consuming fish contaminated with MeHg are also applied to children, but there are few studies available about the effects of low-level postnatal MeHg exposure in them. Objectives: To investigate the association between postnatal methyl mercury exposure and neuropsychological development in a study of children also exposed to lead, both measured at 7 years. Methods: We measured MeHg concentrations in blood samples from the Treatment of Lead-Exposed Children (TLC) trial in which 780 children with elevated concentrations of lead in blood were followed with neuropsychological tests from ages 12–33 months through 7 years. Here we examine blood MeHg concentration and neuropsychological test scores, both measured at age 7 years. We used a maximum likelihood method to estimate geometric mean MeHg concentration and generalized linear regression models to analyze MeHg and neuropsychological test scores. Results: Geometric mean MeHg concentration was 0.56 (95% confidence interval: 0.52, 0.59)μg/L. A 1 μg/L increase in MeHg was associated with a 2.1 (95% confidence interval: 0.4, 3.8) point increase in Full-Scale IQ and 0.2 (95% confidence interval: 0.02, 0.4) point increase in Learning SlopeindexT-score on a test of verbal memory. Conclusions: Our results suggest that the relatively low MeHg exposure in US school-aged children from this population has no detectable adverse effect on neuropsychological development. The positive associations observed between MeHg and neurodevelopment may indirectly reflect consumption of beneficial polyunsaturated fatty acids from seafood. [ABSTRACT FROM AUTHOR]

Although there is empirical support for the link between executive functioning (EF) and visual memory among adults, there has been less exploration of this link among children, especially adolescents. We examined the relation between several EF measures and performance on the Rey-Osterrieth Complex Figure (RCF) in a sample of 160 community adolescents. Each was administered the Wisconsin Card Sorting Test (WCST), Conners Continuous Performance Test (CPT), and the RCF, scored using Bernstein and Waber's (1996) Developmental Scoring System (DSS). Ability to organize the RCF related to memory encoding/retrieval, but not to long-term storage. Indexes derived from the WCST and CPT failed to correlate with any RCF index, raising questions about the relation between DSS scores and EF. Even so, data supported the convergent validity of the DSS system as a reflection of visual-constructional ability and provided evidence of the importance of organizational strategies to visual memory among adolescents. [ABSTRACT FROM AUTHOR]

The effect of lead exposure on cognitive growth patterns was assessed in a longitudinal study of 196 children. Performances on tests of verbal comprehension and perceptual organization (Vocabulary & Block Design. Wechsler Intelligence Scales for Children) were measured at ages 6.5. 11 and 15 years. Growth curve analyses revealed that the quadratic model best described the relationship between test scores and age. Children with higher lead levels, as measured at age 15 years, demonstrated lower verbal comprehension scores over time and greater decline in their rate of Vocabulary development at age 15 years, as compared to children with lower lead levels. Lead exposure was not significantly associated with growth in perceptual organization test scores. Socioeconomic status and maternal intelligence were statistically significantly associated with growth patterns for both test scores, independent of the effects of lead. The findings suggest that lead negatively impacts the developmental progression of specific cognitive skills from childhood through adolescence. [ABSTRACT FROM AUTHOR]

ABSTRACT In an effort to characterize how a child goes about learning and recalling information, the developers of the California Verbal Learning Test for Children (CVLT-C) provided normative data related to both learning outcome and learning process. The present study examined the assertion that CVLT-C process indices relate to executive functioning in a sample of community-dwelling adolescents. Contrary to predictions, measures of executive functioning typically correlated poorly with measures of learning process, despite displaying significant correlations with measures of learning outcome. Although further research is recommended, these findings do not support the clinical interpretation of CVLT-C process indices as reflections of executive functioning. [ABSTRACT FROM AUTHOR]

Presents several letters to the editors concerning the effects of lead on child development. Correlation between neonatal blood lead concentration and neurobehavioral outcomes; Complexity of Kaufman assessment battery for children; Advantage of the Kaufman test.