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: 4.37). 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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    • "Most health studies on Mn overexposure report on occupational exposures to Mn (Meyer-Baron et al., 2013). Few studies on adults have examined adverse effects of environmental exposures to Mn, which tend to be much lower compared to occupational exposures (Bowler et al., 2011; Haynes et al., 2010; Kim et al., 2011; Mergler et al., 1999; Rodriquez-Agudelo et al., 2006; Solís-Vivanco et al., 2009; Baldwin et al., 1999; Menezes-Filho et al., 2011). The published literature on environmental Mn studies examining motor and tremor function is sparse (Solís-Vivanco et al., 2009; Rodriquez-Agudelo et al., 2006; Baldwin et al., 1999; Kim et al., 2011; Bowler et al., 2012). "
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    ABSTRACT: Background: Manganese (Mn) inhalation has been associated with neuropsychological and neurological sequelae in exposed workers. Few environmental epidemiologic studies have examined the potentially neurotoxic effects of Mn exposure in ambient air on motor function and hand tremor in adult community residents. Mn exposed residents were recruited in two Ohio towns: Marietta, a town near a ferro-manganese smelter, and East Liverpool, a town adjacent to a facility processing, crushing, screening, and packaging Mn products. Methods: Chronic (≥10years) exposure to ambient air Mn in adult residents and effects on neuropsychological and neurological outcomes were investigated. Participants from Marietta (n=100) and East Liverpool (n=86) were combined for analyses. AERMOD dispersion modeling of fixed-site outdoor air monitoring data estimated Mn inhalation over a ten year period. Adult Mn-exposed residents' psychomotor ability was assessed using Finger Tapping, Hand Dynamometer, Grooved Pegboard, and the Computerized Adaptive Testing System (CATSYS) Tremor system. Bayesian structural equation modeling was used to assess associations between air-Mn and motor function and tremor. Results: Air-Mn exposure was significantly correlated in bivariate analyses with the tremor test (CATSYS) for intensity, center frequency and harmonic index. The Bayesian path analysis model showed associations of air-Mn with the CATSYS non-dominant center frequency and harmonic index; while the Bayesian structural equation model revealed associations between air-Mn and lower Finger Tapping scores. Household income was significantly associated with motor dysfunction but not with tremor. Conclusion: Tremor and motor function were associated with higher exposure to airborne Mn.
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    • "months and concurrent mental development, with deficits at the lowest and highest quintiles (Claus Henn et al., 2010). In crosssectional studies of school-aged children, higher Mn levels in hair, blood and drinking water have been associated with lower fullscale and verbal intelligence quotients (Kim et al., 2009; Riojas- Rodriguez et al., 2010; Bouchard et al., 2011; Menezes-Filho et al., 2011; Wasserman et al., 2011); lower verbal learning and memory scores (Torres-Agustin et al., 2013); and poorer motor coordination (Lucchini et al., 2012). In prospective studies, higher cord blood Mn levels have been associated with poorer neonatal behavior in a non-linear fashion (Yu et al., 2014); poorer cognition and language in 2-year-olds (Lin et al., 2013); and poorer attention, non-verbal memory, and hand skills in 3-year-olds (Takser et al., 2003). "
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    ABSTRACT: Introduction: Manganese (Mn) is an essential nutrient but higher exposure has been associated with poorer neurodevelopment in children. Methods: We measured Mn levels in prenatal (Mnpre) (n=197) and postnatal (Mnpost) dentin (n=193) from children's shed teeth using laser ablation inductively coupled plasma mass spectroscopy and examined the relationship with children's scores on the Mental Development Index (MDI) and Psychomotor Development Index (PDI) on the Bayley Scales of Infant Development at 6, 12, and 24-months. We explored non-linear associations and interactions by sex, blood lead concentrations and maternal iron status during pregnancy. Results: A two-fold increase of Mnpost levels in dentin was associated with small decreases in MDI at 6-months and 12-months of age. We also observed a non-linear relationship between Mnpost levels and PDI at 6-months. We found effect modification by sex for Mnpost levels and neurodevelopment at 6-months with stronger effects among girls for both MDI (-1.5 points; 95% Confidence Interval (CI): -2.4, -0.6) and PDI (-1.8 points; 95% CI: -3.3, -0.3). Girls whose mothers had lower hemoglobin levels experienced larger decreases in MDI and PDI associated with Mnpre levels than girls whose mothers had higher hemoglobin levels (pinteraction=0.007 and 0.09, respectively). We did not observe interactions with blood lead concentrations or any relationships with neurodevelopment at 24-months. Conclusions: Using Mn measurements in tooth dentin, a novel biomarker that provides prenatal and early postnatal levels, we observed negative transient associations between postnatal Mn levels and early neurodevelopment with effect modification by sex and interactions with prenatal hemoglobin.
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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.
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