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Manganese Exposure and Neurocognitive Outcomes in Rural School-Age Children: The Communities Actively Researching Exposure Study (Ohio, USA).

Haynes EN, Sucharew H, Kuhnell P, Alden J, Barnas M, Wright RO, Parsons PJ, Aldous KM, Praamsma ML, Beidler C, Dietrich KN - Environ. Health Perspect. (2015)

Bottom Line: After adjusting for potential confounders, both low and high blood and hair Mn concentrations were associated with lower Full Scale IQ and subscale scores, with significant negative associations between the highest quartile and middle two quartiles of blood Mn (β -3.51; 95% CI: -6.64, -0.38) and hair Mn (β -3.66; 95% CI: -6.9, -0.43%) and Full Scale IQ.Both low and high Mn concentrations in blood and hair were negatively associated with child IQ scores.Serum cotinine was negatively associated with child cognitive function.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA.

ABSTRACT

Background: Manganese (Mn) plays a vital role in brain growth and development, yet excessive exposure can result in neurotoxicity. Marietta, Ohio, is home to the nation's longest-operating ferromanganese refinery, and community concern about exposure led to the development of the research study.

Objectives: Our overall goal was to address the community's primary research question: "Does Mn affect cognitive development of children?" We evaluated the relationships between Mn exposure as measured by blood and hair Mn, along with other neurotoxicants including blood lead (Pb) and serum cotinine, and child cognition.

Methods: Children 7-9 years of age were enrolled (n = 404) in the Communities Actively Researching Exposure Study (CARES) from Marietta and Cambridge, Ohio, and their surrounding communities from October 2008 through March 2013. Blood and hair were analyzed for Mn and Pb, and serum was analyzed for cotinine. We used penalized splines to assess potential nonlinear associations between biological measures and IQ subscale scores, followed by multivariable regression models with categorical variables based on quartiles of the distribution for biological measures with nonlinear associations and continuous variables for biological measures with linear associations.

Results: Geometric mean blood (n = 327) and hair Mn (n = 370) concentrations were 9.67 ± 1.27 μg/L and 416.51 ± 2.44 ng/g, respectively. After adjusting for potential confounders, both low and high blood and hair Mn concentrations were associated with lower Full Scale IQ and subscale scores, with significant negative associations between the highest quartile and middle two quartiles of blood Mn (β -3.51; 95% CI: -6.64, -0.38) and hair Mn (β -3.66; 95% CI: -6.9, -0.43%) and Full Scale IQ.

Conclusions: Both low and high Mn concentrations in blood and hair were negatively associated with child IQ scores. Serum cotinine was negatively associated with child cognitive function.

No MeSH data available.


Related in: MedlinePlus

Penalized splines for hair and blood Mn levels in association with WISC-IV outcome measures. All models include both hair Mn and blood Mn, plus ln serum creatinine, blood Pb, and community residence. (A) Full Scale IQ (n = 295), also adjusted for sex, parent’s IQ, parent education, parent confidence t-score; (B) Perceptual Reasoning (n = 298) also adjusted for parent’s IQ; and (C) Processing Speed (n = 272), also adjusted for sex, ln serum ferritin, parent confidence t-score, birth weight. The solid line represents the estimate with the 95% confidence interval indicated by dotted lines. The distributions of Mn levels are indicated by vertical lines on the x-axis.
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f1: Penalized splines for hair and blood Mn levels in association with WISC-IV outcome measures. All models include both hair Mn and blood Mn, plus ln serum creatinine, blood Pb, and community residence. (A) Full Scale IQ (n = 295), also adjusted for sex, parent’s IQ, parent education, parent confidence t-score; (B) Perceptual Reasoning (n = 298) also adjusted for parent’s IQ; and (C) Processing Speed (n = 272), also adjusted for sex, ln serum ferritin, parent confidence t-score, birth weight. The solid line represents the estimate with the 95% confidence interval indicated by dotted lines. The distributions of Mn levels are indicated by vertical lines on the x-axis.

Mentions: Association between biomarkers and cognitive function. The generalized linear models revealed nonlinear associations between Mn (hair and blood) and WISC-IV outcomes (Full Scale IQ: hair p = 0.01 and blood p = 0.041; Perceptual Reasoning: hair p = 0.09 and blood p = 0.04; Processing Speed: hair p = 0.08 and blood p = 0.06) (Figure 1). To account for this nonlinear association and to evaluate the upper and lower extremes of Mn levels, we fit a multivariable regression model with indicator variables for the lowest and highest quartiles of Mn (hair and blood) with the reference group set to the middle two quartiles of Mn distribution (i.e., within the 25th to 75th percentiles) (Table 2). The highest quartile of Mn, both hair and blood, was significantly associated with lower mean Full Scale IQ scores compared to the middle two quartiles of Mn. Mean Full Scale IQ was lower in the lowest quartile than the middle two quartiles of Mn, hair, and blood, but did not reach statistical significance. For Perceptual Reasoning, both the lowest and highest quartiles of hair Mn and the highest quartile of blood Mn were associated with significantly lower mean scores compared to the middle two quartiles. The highest quartile of blood Mn was also associated with lower mean Processing Speed compared with the middle two quartiles. Although associations were not statistically significant, scores for Working Memory and Verbal Comprehension also were lower, on average, among children with the lowest and highest values of hair and blood Mn, compared with children in the middle two quartiles of each exposure. In the multivariable models, a 1-unit increase in blood Pb was associated with significantly lower Processing Speed [β = –3.53; 95% confidence interval (CI): –6.95, –0.12], and ln-transformed serum cotinine was significantly associated with lower scores for Full Scale IQ and all domains except Processing Speed (e.g., β = –1.42; 95% CI: –2.23, –0.60 for Full Scale IQ).


Manganese Exposure and Neurocognitive Outcomes in Rural School-Age Children: The Communities Actively Researching Exposure Study (Ohio, USA).

Haynes EN, Sucharew H, Kuhnell P, Alden J, Barnas M, Wright RO, Parsons PJ, Aldous KM, Praamsma ML, Beidler C, Dietrich KN - Environ. Health Perspect. (2015)

Penalized splines for hair and blood Mn levels in association with WISC-IV outcome measures. All models include both hair Mn and blood Mn, plus ln serum creatinine, blood Pb, and community residence. (A) Full Scale IQ (n = 295), also adjusted for sex, parent’s IQ, parent education, parent confidence t-score; (B) Perceptual Reasoning (n = 298) also adjusted for parent’s IQ; and (C) Processing Speed (n = 272), also adjusted for sex, ln serum ferritin, parent confidence t-score, birth weight. The solid line represents the estimate with the 95% confidence interval indicated by dotted lines. The distributions of Mn levels are indicated by vertical lines on the x-axis.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590758&req=5

f1: Penalized splines for hair and blood Mn levels in association with WISC-IV outcome measures. All models include both hair Mn and blood Mn, plus ln serum creatinine, blood Pb, and community residence. (A) Full Scale IQ (n = 295), also adjusted for sex, parent’s IQ, parent education, parent confidence t-score; (B) Perceptual Reasoning (n = 298) also adjusted for parent’s IQ; and (C) Processing Speed (n = 272), also adjusted for sex, ln serum ferritin, parent confidence t-score, birth weight. The solid line represents the estimate with the 95% confidence interval indicated by dotted lines. The distributions of Mn levels are indicated by vertical lines on the x-axis.
Mentions: Association between biomarkers and cognitive function. The generalized linear models revealed nonlinear associations between Mn (hair and blood) and WISC-IV outcomes (Full Scale IQ: hair p = 0.01 and blood p = 0.041; Perceptual Reasoning: hair p = 0.09 and blood p = 0.04; Processing Speed: hair p = 0.08 and blood p = 0.06) (Figure 1). To account for this nonlinear association and to evaluate the upper and lower extremes of Mn levels, we fit a multivariable regression model with indicator variables for the lowest and highest quartiles of Mn (hair and blood) with the reference group set to the middle two quartiles of Mn distribution (i.e., within the 25th to 75th percentiles) (Table 2). The highest quartile of Mn, both hair and blood, was significantly associated with lower mean Full Scale IQ scores compared to the middle two quartiles of Mn. Mean Full Scale IQ was lower in the lowest quartile than the middle two quartiles of Mn, hair, and blood, but did not reach statistical significance. For Perceptual Reasoning, both the lowest and highest quartiles of hair Mn and the highest quartile of blood Mn were associated with significantly lower mean scores compared to the middle two quartiles. The highest quartile of blood Mn was also associated with lower mean Processing Speed compared with the middle two quartiles. Although associations were not statistically significant, scores for Working Memory and Verbal Comprehension also were lower, on average, among children with the lowest and highest values of hair and blood Mn, compared with children in the middle two quartiles of each exposure. In the multivariable models, a 1-unit increase in blood Pb was associated with significantly lower Processing Speed [β = –3.53; 95% confidence interval (CI): –6.95, –0.12], and ln-transformed serum cotinine was significantly associated with lower scores for Full Scale IQ and all domains except Processing Speed (e.g., β = –1.42; 95% CI: –2.23, –0.60 for Full Scale IQ).

Bottom Line: After adjusting for potential confounders, both low and high blood and hair Mn concentrations were associated with lower Full Scale IQ and subscale scores, with significant negative associations between the highest quartile and middle two quartiles of blood Mn (β -3.51; 95% CI: -6.64, -0.38) and hair Mn (β -3.66; 95% CI: -6.9, -0.43%) and Full Scale IQ.Both low and high Mn concentrations in blood and hair were negatively associated with child IQ scores.Serum cotinine was negatively associated with child cognitive function.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, Ohio, USA.

ABSTRACT

Background: Manganese (Mn) plays a vital role in brain growth and development, yet excessive exposure can result in neurotoxicity. Marietta, Ohio, is home to the nation's longest-operating ferromanganese refinery, and community concern about exposure led to the development of the research study.

Objectives: Our overall goal was to address the community's primary research question: "Does Mn affect cognitive development of children?" We evaluated the relationships between Mn exposure as measured by blood and hair Mn, along with other neurotoxicants including blood lead (Pb) and serum cotinine, and child cognition.

Methods: Children 7-9 years of age were enrolled (n = 404) in the Communities Actively Researching Exposure Study (CARES) from Marietta and Cambridge, Ohio, and their surrounding communities from October 2008 through March 2013. Blood and hair were analyzed for Mn and Pb, and serum was analyzed for cotinine. We used penalized splines to assess potential nonlinear associations between biological measures and IQ subscale scores, followed by multivariable regression models with categorical variables based on quartiles of the distribution for biological measures with nonlinear associations and continuous variables for biological measures with linear associations.

Results: Geometric mean blood (n = 327) and hair Mn (n = 370) concentrations were 9.67 ± 1.27 μg/L and 416.51 ± 2.44 ng/g, respectively. After adjusting for potential confounders, both low and high blood and hair Mn concentrations were associated with lower Full Scale IQ and subscale scores, with significant negative associations between the highest quartile and middle two quartiles of blood Mn (β -3.51; 95% CI: -6.64, -0.38) and hair Mn (β -3.66; 95% CI: -6.9, -0.43%) and Full Scale IQ.

Conclusions: Both low and high Mn concentrations in blood and hair were negatively associated with child IQ scores. Serum cotinine was negatively associated with child cognitive function.

No MeSH data available.


Related in: MedlinePlus