Article

Elevated manganese and cognitive performance in school-aged children and their mothers

Laboratory of Toxicology, College of Pharmacy, Federal University of Bahia, Brazil.
Environmental Research (Impact Factor: 3.95). 10/2010; 111(1):156-63. DOI: 10.1016/j.envres.2010.09.006
Source: PubMed

ABSTRACT Growing evidence suggests that excess manganese (Mn) in children is associated with neurobehavioral impairments. In Brazil, elevated hair Mn concentrations were reported in children living near a ferro-manganese alloy plant.
We investigated these children's and caregivers' cognitive function in relation to bioindicators of Mn exposure.
In this cross-sectional study, the WISC-III was administered to 83 children aged between 6 and 12 years; the Raven Progressive Matrix was administered to the primary caregivers (94% mothers), who likewise responded to a questionnaire on socio demographics and birth history. Mn in hair (MnH) and blood (MnB) and blood lead (PbB) were measured by graphite furnace atomic absorption spectrometry (GFAAS).
Children's mean MnB and MnH were 8.2 μg/L (2.7-23.4) and 5.83 μg/g (0.1-86.68), respectively. Mean maternal MnH was 3.50 μg/g (0.10-77.45) and correlated to children's MnH (rho=0.294, p=0.010). Children's MnH was negatively related to Full-Scale Intelligence Quotient (IQ) and Verbal IQ; β coefficients for MnH were -5.78 (95% CI -10.71 to -0.21) and -6.72 (-11.81 to -0.63), adjusted for maternal education and nutritional status. Maternal MnH was negatively associated with performance on the Raven's (β=-2.69, 95% CI -5.43 to 0.05), adjusted for education years, family income and age.
These findings confirm that high MnH in children is associated with poorer cognitive performance, especially in the verbal domain. Primary caregiver's IQ is likewise associated to Mn exposure, suggesting that, in this situation, children's cognition may be affected directly and indirectly by Mn exposure.

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    • "Postnatal Mn exposure has been associated with poor language development in toddler boys (Rink et al., 2014), and behavioral problems in schoolaged boys and girls (Ericson et al., 2007). Studies of school-aged children and adolescents (6–14 year olds) have linked elevated Mn levels in drinking water, blood, and hair samples with oppositional behavior and hyperactivity (Bouchard et al., 2007), impaired cognitive abilities (Bouchard et al., 2011b; Kim et al., 2009; Menezes-Filho et al., 2011; Riojas-Rodriguez et al., 2010; Wasserman et al., 2006), and poor memory (He et al., 1994; Torres-Agustin et al., 2013), motor coordination (He et al., 1994; Hernandez-Bonilla et al., 2011; Lucchini et al., 2012), and visuoperceptive speed (He et al., 1994; Zhang et al., 1995). To date, only one epidemiologic study has assessed exposure to Mn both prenatally and postnatally (Ericson et al., 2007). "
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    ABSTRACT: Numerous cross-sectional studies of school-age children have observed that exposure to manganese (Mn) adversely affects neurodevelopment. However, few prospective studies have looked at the effects of both prenatal and postnatal Mn exposure on child neurodevelopment. We measured Mn levels in prenatal and early postnatal dentine of shed teeth and examined their association with behavior, cognition, memory, and motor functioning in 248 children aged 7, 9, and/or 10.5years living near agricultural fields treated with Mn-containing fungicides in California. We used generalized linear models and generalized additive models to test for linear and nonlinear associations, and generalized estimating equation models to assess longitudinal effects. We observed that higher prenatal and early postnatal Mn levels in dentine of deciduous teeth were adversely associated with behavioral outcomes, namely internalizing, externalizing, and hyperactivity problems, in boys and girls at 7 and 10.5years. In contrast, higher Mn levels in prenatal and postnatal dentine were associated with better memory abilities at ages 9 and 10.5, and better cognitive and motor outcomes at ages 7 and 10.5years, among boys only. Higher prenatal dentine Mn levels were also associated with poorer visuospatial memory outcomes at 9years and worse cognitive scores at 7 and 10.5years in children with higher prenatal lead levels (≥0.8μg/dL). All these associations were linear and were consistent with findings from longitudinal analyses. We observed that higher prenatal and early postnatal Mn levels measured in dentine of deciduous teeth, a novel biomarker that provides reliable information on the developmental timing of exposures to Mn, were associated with poorer behavioral outcomes in school-age boys and girls and better motor function, memory, and/or cognitive abilities in school-age boys. Additional research is needed to understand the inconsistencies in the neurodevelopmental findings across studies and the degree to which differences may be associated with different Mn exposure pathways and biomarkers. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Environment international 07/2015; 84:39-54. DOI:10.1016/j.envint.2015.07.009 · 5.66 Impact Factor
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    • "Mn and cognitive effects 1.2.1. Cognitive effects in children using neuropsychological testing The large majority of studies in the literature that focus on environmental Mn exposure and neuropsychological effects are in children (Wasserman et al., 2006, 2011; Wright et al., 2006; Kim et al., 2009; Riojas-Rodríguez et al., 2010; Bouchard et al., 2011; Menezes-Filho et al., 2011; Khan et al., 2012; Torres-Agustín et al., 2013; He et al., 1994; Lucchini et al., 2012; Haynes et al., 2010, 2012, 2015). These studies have reported decreased verbal, performance, and intellectual ability associated with level of Mn exposure using Mn in hair or blood as a biomarker. "
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    • "In children, manganese exposure has been associated with the prevalence of attention deficit hyperactivity disorder (ADHD) (Bouchard et al. 2007, 2011; Woolf et al. 2002) and negatively associated with IQ scores (Wasserman et al. 2006; Wright et al. 2006). There have been recent reports of negative associations between exposure to manganese and cognition, memory, and motor function in children (Bouchard et al. 2011; Khan et al. 2012; Lucchini et al. 2012; Menezes-Filho et al. 2011; Meyer-Baron et al. 2013; Takser et al. 2003; Wasserman et al. 2006). "
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