IQ Scores Of Children Research Articles

2 Sex difference of Developmental Neurotoxicants on Intellectual Abilities: A Systematic Review and Meta-Analysis

Objective:Early life exposures to lead, mercury, polychlorinated biphenyls (PCBs), polybromide diphenyl ethers (PBDEs), organophosphate pesticides (OPPs), and phthalates have been associated with diminished IQ scores in children. Some studies suggest that these neurotoxicants impact boys and girls differently. We conducted a systematic review and meta-analysis to identify and quantify sex differences in IQ deficits from pre- and post-natal exposures to these developmental neurotoxicants.Participants and Methods:We used PubMed and PsychINFO to screen abstracts of articles published between January 1, 1950 and December 31, 2021 for empirical studies of six neurotoxicants [lead, mercury, PCBs, PBDEs, OPPs, and/or phthalates] that (1) used an individualized biomarker; (2) measured exposure during the prenatal period or within the first six years of life; and (3) provided different effect estimates on children's intellectual abilities by sex. We assessed each study for risk of bias using Navigation Guide (Woodruff & Sutton, 2014). For studies with combinable data, we performed separate random effects meta-analyses for boys and girls with subgroup analyses by neurotoxicant. To homogenize the magnitude of effect observed in each study, we recalculated results to be expressed as the absolute change in intellectual abilities for a relative change of 1.5 times (i.e., 50% increase) in the exposure variable.Results:Of 3205 studies screened, 53 met inclusion criteria: 34 evaluated prenatal exposure, 11 postnatal exposure, and 8 both pre- and post-natal exposure. We generally rated these studies as "low" to "probably low" risk of bias. Among the studies examining prenatal exposure, 27 reported no significant differences between the sexes, 7 found negative associations in boys, 4 found negative associations in girls, 5 found negative nonsignificant associations in boys and positive nonsignificant associations in girls, and 3 found no clear pattern, where differences by sex depended on the specific phthalate compound or outcome measurement. Among the studies examining postnatal exposure, 14 reported no significant differences between the sexes, 1 found a negative association in boys, 2 found negative associations in girls, and 2 found positive associations for either boys or girls. In our meta-analysis of 16 studies (4 lead, 4 mercury, 2 PBDEs, 2 OPPs, 4 phthalates), we found that prenatal exposure to developmental neurotoxicants was associated with decreased full-scale intelligence in boys (B = -0.26; 95% CI: -0.45, -0.08), but not girls (B = 0.09; 95% CI: -0.14, 0.31). In subgroup analyses by neurotoxicant, prenatal exposure to lead (B = -1.07; 95% CI: -1.63, -0.52), and ZPBDEs (B = -0.57; 95% CI: -1.14, -0.01) were associated with decreased full-scale intelligence in boys, whereas the girls' effect sizes were consistently near zero.Conclusions:During fetal development, boys appear to be more vulnerable than girls to IQ deficits from neurotoxic exposures, and especially from lead and PBDEs. More research is needed to examine the nuanced sex-specific effects found for postnatal exposures to toxic chemicals.

Does pre-school developmental assessment agree with later intellectual assessment? A retrospective cohort study.

This study sought to assess the association between early developmental assessment of toddlers with idiopathic global developmental delay (GDD) and their later intelligence test scores. Toddlers with idiopathic GDD attending a community clinic over a 6-year period were assessed initially using the Griffiths Mental Development Scales - Extended Revised version (GMDS-ER) and later completing formal intelligence testing using the Stanford-Binet Intelligence Scale - 5th Edition (SB5) at age 4-6 years. Spearman's correlation was used to assess the association of quotient scores across the tools. The composite quotient (GQ) and the subscale quotients of GMDS-ER were correlated with the full-scale IQ (FSIQ), verbal and non-verbal IQ scores from the SB5. Thirty of 153 children assessed at the clinic were eligible for the study. The correlation between GMDS-ER GQ and later SB5 FSIQ was strong (r = 0.86, P < 0.001). The subscales' associations were moderate to strong (0.48-0.71). Eighty-six percent (86%) of children with delay on GMDS-ER GQ were found later to be in the impaired category based on the FSIQ of the SB5. There was a strong association between toddlers' early developmental quotients and later IQ scores for children with idiopathic GDD, though agreement between early GDD diagnoses and later intellectual disability is not absolute. Individualised care is needed around prognostic advice and recommendations to caregivers and families in the early years, so they may effectively plan for interventions, supports and later reassessment to optimise their child's development and learning.

Association between low fluoride exposure and children's intelligence: a meta-analysis relevant to community water fluoridation

ObjectivesPrevious meta-analyses have mainly focused on studies conducted in endemic fluorosis areas with relatively high fluoride concentrations. These are impoverished rural communities in China, India, and Iran, and the findings cannot be generalised to developed countries. Therefore, we investigated the association between fluoride concentrations relevant to community water fluoridation and children's cognition measured with IQ scores by synthesising effect sizes reported in observational studies. MethodsA previous meta-analysis and the National Toxicology Program database that included a search of multiple databases and the authors' search of PubMed, Google Scholar, and Mendeley provided the data. Cross-sectional and cohort studies examining the association between fluoride and children's cognition and intelligence scores were selected. Two reviewers abstracted data using standard procedures. We performed three meta-analyses to synthesise the effects using the random effects models. ResultsEight studies of standardized mean difference in IQ scores from non-endemic fluorosis areas found no statistically significant difference between recommended and lower levels of fluoride (standardized mean difference = 0.07; 95% confidence interval: −0.02, 0.17; I2 = 0%), and no significant fluctuation in IQ scores across the differences in fluoride concentrations by non-linear modeling with restricted cubic spline (P = 0.21). Meta-analyses of children's and maternal spot urinary fluoride associated pooled regression coefficients (Betachildren = 0.16; 95% confidence interval: −0.40, 0.73; P = 0.57; I2 = 0%, Betamaternal = −0.92; 95% CI: −3.29, 1.46; P = 0.45; I2 = 72%) were not statistically significant. Further regression analysis by standardizing absolute mean IQ scores from lower fluoride areas did not show a relationship between F concentration and IQ scores (Model Likelihood-ratio test: P-value = 0.34.) ConclusionsThese meta-analyses show that fluoride exposure relevant to community water fluoridation is not associated with lower IQ scores in children. However, the reported association observed at higher fluoride levels in endemic areas requires further investigation.

Manganese (Mn) in Drinking Water From Gravity Feed System: A Literature Review

Manganese (Mn) is an element of metals that exists in a huge number of metals in the Earth’s crust. Mn is not naturally found in its pure form; instead, it is usually forming a compound with iron. Mn is an important element that has a function in both animals and humans [1]. Mn is commonly used in the manufacture and as an ingredient in several products such as batteries, glass and fireworks. Besides, Mn compounds are also present in surface waters in dissolved and suspended forms [2]. Besides ores and rocks, Mn can also be found in groundwater and surface water due to reducing conditions in soils and rocks that contain Mn, which may erode and turn it into a soluble form that then enters the water naturally [3]. Thus, high levels of Mn are found in groundwater and some lakes as well as reservoirs due to these conditions. Mn can also be present in water in the environment through human activities such as mining and landfill leaching near the water [4]. Health Canada stated the prevalence of Mn in ground waters is higher than that of surface waters [5].&#x0D; &#x0D; Inhalation and ingestion are the main routes of exposure, with inhalation mostly happening in workers due to occupational factors, and those who consume food or drinking water that contains high amounts of Mn are exposed through ingestion [4]. However, Mn is easily absorbed into the body when consumed with drinking water as compared to ingestion with food. Mn levels in drinking water should not be more than 0.1 mg/L, based on the Drinking Water Quality Standard [6]. Many enzymes including manganese superoxide dismutase arginase and pyruvate carboxylase require Mn as a cofactor; while in combination with vitamin K, Mn can aid in blood coagulation and hemostasis [7]. In addition, Mn is involved in the metabolism of amino acids, cholesterol, glucose and carbohydrates as well as bone formation, reproduction and immune response [8]. However, problems with memory, attention and motor skills exist when children and adults alike consume high levels of Mn for extended durations including consumption of drinking water [9]. There are no strong studies that show the results of the health effects of Mn in drinking water for adults. However, many studies have shown evidence of adverse health effects of Mn exposure on children especially in term of neurobehavioral effect.&#x0D; &#x0D; A review was conducted on the literature on Mn exposure from drinking water, concentrating on the World Health Organization's health-based Mn guideline value [10]. There is no study that has determined a lethal threshold of Mn for children and newborns, although data suggest that youngsters are more susceptible to poisoning than adults. Another study reported the association between Mn and arsenic exposure in drinking water among academic achievement of children in Bangladesh. It showed a significant association between water containing more than 400µg/L and decreased mathematical scores observed after adjusting the confounders [8]. There is a significant decrease in IQ scores of children that were exposed to higher levels of Mn from the earlier study [11]. Changes in the neurotransmitter system were shown to vary with the period of exposure during Mn intoxication in mice exposed to manganese chloride (MnCl2) through lactation and drinking water containing 3 mg/L Mn for 180 days, and male rats given 1000 mg/L water for 360 days. The studies also showed that Mn exposure increased the levels of dopamine, norepinephrine and tyrosine in the corpus striatum [5].&#x0D; &#x0D; The gravity feed system (GFS) is a downstream distribution system that is powered by gravity to supply water to households without the need to use electricity [12]. It is commonly used by populations living in hilly areas. These include the Orang Asli communities which usually live in areas which cannot be supplied with centralized water supply system. GFS is suitable in areas with a continuous supply of spring water. In Malaysia, gravity feed system is a type of water delivery system that includes a secure catchment area, a weir or sluice, and a piped water supply network (Figure 1). Since the majority of the systems generate untreated but healthy water, rural residents are recommended to boil the water [13].

Psychosocial and Socioeconomic Factors in Children with Neurofibromatosis Type 1

AbstractThe aim of this study is to analyze whether children with familial and sporadic neurofibromatosis type 1 (NF1) differ in psychosocial and socioeconomic aspects such as developmental delay as well as in comorbidities. Medical records of 250 children with NF1 at a median age of 10.6 years (range = 2–20 years at time of data collection) were retrospectively reviewed. Specifically, psychosocial and socioeconomic factors from 88 children with a family history for NF1 and 162 sporadic cases were compared. Comparing IQ, familial cases scored significantly lower than sporadic cases (89.8 vs. 96.5; p = 0.015). IQ scores of children with familial and sporadic NF1 differ depending on level of parental education (mean IQ for high education 101.3 [familial] and 102.8 [sporadic] vs. low education 87.5 [familial] and 90.4 [sporadic]; p &lt; 0.001). No significant differences were found regarding the presence of developmental delay, learning disorders, autism spectrum disorder, or attention deficit hyperactivity disease. Children with inherited NF1 had a significantly lower IQ than sporadic cases. Children with familial NF1 more often had parents with a lower level of education, highlighting a possible impact of NF1 through generations. Also, the present study confirmed previous results in literature regarding high frequencies of learning disabilities, autism spectrum disease, and attention deficits in children with NF1.

Fluoride exposure, dopamine relative gene polymorphism and intelligence: A cross-sectional study in China

BackgroundExcessive fluoride exposure is related to adverse health outcomes, but whether dopamine (DA) relative genes are involved in the health effect of low-moderate fluoride exposure on children’s intelligence remain unclear. ObjectivesWe conducted a cross-sectional study to explore the role of DA relative genes in the health effect of low-moderate fluoride exposure in drinking water. MethodsWe recruited 567 resident children, aged 6–11 years old, randomly from endemic and non-endemic fluorosis areas in Tianjin, China. Spot urine samples were tested for urinary fluoride concentration, combined Raven`s test was used for intelligence quotient test. Fasting venous blood were collected to analyze ANKK1 Taq1A (rs1800497), COMT Val158Met (rs4680), DAT1 40 bp VNTR and MAOA uVNTR. Multivariable linear regression models were used to assess associations between fluoride exposure and IQ scores. We applied multiplicative and additive models to appraise single gene-environment interaction. Generalized multifactor dimensionality reduction (GMDR) was used to evaluate high-dimensional interactions of gene-gene and gene-environment. ResultsIn adjusted model, fluoride exposure was inversely associated with IQ scores (β = −5.957, 95% CI: −9.712, −2.202). The mean IQ scores of children with high-activity MAOA genotype was significantly lower than IQ scores of those with low-activity (P = 0.006) or female heterozygote (P = 0.016) genotype. We detected effect modification by four DA relative genes (ANKK1, COMT, DAT1 and MAOA) on the association between UF and IQ scores. We also found a high-dimensional gene-environment interaction among UF, ANKK1, COMT and MAOA on the effect of IQ (testing balanced accuracy = 0.5302, CV consistency: 10/10, P = 0.0107). ConclusionsOur study suggests DA relative genes may modify the association between fluoride and intelligence, and a potential interaction among fluoride exposure and DA relative genes on IQ.

Do childhood socioeconomic circumstances moderate the association between childhood cognitive ability and all-cause mortality across the life course? Prospective observational study of the 36-day sample of the Scottish Mental Survey 1947

BackgroundThere is growing evidence that higher childhood cognitive ability predicts lower all-cause mortality risk across the life course. Whereas this association does not appear to be mediated by childhood socioeconomic...

Organophosphate pesticides exposure during fetal development and IQ scores in 3 and 4-year old Canadian children

BackgroundOrganophosphate pesticides are widely used in agriculture and for other purposes, leading to ubiquitous exposure in human populations. Some studies reported cognitive deficits in children exposed prenatally to organophosphate pesticides, but findings from recent studies were inconsistent. Furthermore, recent biomonitoring studies suggest exposure levels have decreased. Hence, the risks from current prenatal exposure to organophosphate pesticides for child neurodevelopment are uncertain. Furthermore, sex-differences also remain to be better documented in relation to potential neurodevelopmental effects. ObjectiveTo examine the association between prenatal exposure to organophosphate pesticides and IQ scores among boys and girls living in several major Canadian cities. MethodsWe used data from the MIREC cohort (Maternal-Infant Research on Environmental Chemicals). Women were recruited in 2008–2011 from 10 Canadian cities during their first trimester of pregnancy, and urine spot samples were collected for measurement of three dimethyl alkyl phosphate (DMAP) and three diethyl alkyl phosphate (DEAP) metabolites. When children were 3–4 years of age, we used the Wechsler Preschool and Primary Scales of Intelligence-III (WPPSI-III) to assess cognitive ability of children from 6 out of the 10 cities (Halifax, Hamilton, Kingston, Montreal, Toronto, and Vancouver). We analysed the association between maternal exposure to organophosphate pesticides (DMAP and DEAP urinary metabolites) and children's IQ scores with generalized estimating equations (GEEs) to take into account the clustered-data resulting from the six study sites. All analyses were sex-stratified (n = 296 boys and 311 girls). ResultsThe participants were predominantly well-educated, white women, with a relatively high household income. Children had a mean age of 3.4 years at the moment of IQ assessment (range, 3.0–4.1 years). In girls, there was no association between IQ scores and DEAPs or DMAPs. Higher concentrations of DEAPs were significantly associated with poorer Verbal IQ scores (for a 10-fold increase in concentrations, −6.28; 95% CIs, −12.13, −0.43) in boys. The association for Performance IQ in boys also indicated poorer scores with higher DEAP concentrations, but the confidence intervals included the null value (−4.05; 95% CIs, −10.19, 2.10). The relation between DMAPs and IQ scores in boys was also negative, but association estimates were small and not significant. ConclusionUrinary metabolites of organophosphate pesticides were not associated with IQ in girls, but we observed that higher maternal urinary DEAPs were associated with poorer Verbal IQ in boys. However, exposure misclassification may be an issue as only one urine sample per woman was analysed. The present study contributes to the accumulating evidence linking exposure to organophosphate pesticides during fetal development with poorer cognitive function in children, bringing data on the risks in a context of low exposure levels encountered in primarily urban populations from Canada.

Intelligence in offspring born to women exposed to intimate partner violence: a population-based cohort study.

Background: Intimate partner violence (IPV) is a risk factor for developmental problems in offspring. Despite a high prevalence of IPV in the UK and elsewhere, the longer-term outcomes of offspring born to exposed mothers remain under-researched. Methods: Population-based cohort study. We assessed IPV prevalence by type and timing for 3,153 mother-child pairs with complete data within our study population and examined associations between IPV and offspring IQ. We used multiple-imputation to evaluate bias due to our exclusion of observations with missing covariate data. Results: Nearly one in five mothers reported IPV during the study period, with 17.6% reporting emotional violence and 6.8% reporting physical violence. Taking into account potential confounders, the IQ scores of children born to mothers exposed to physical violence remained lower than those of maternally unexposed children (full-scale IQ = -2.8 points [95%CI -4.9 to -0.7], verbal IQ = -2.2 [95%CI -4.4 to -0.1], performance IQ = -2.7 [95%CI -5.0 to -0.5]) and odds of below-average intelligence (IQ<90) remained increased for full-scale (OR 1.48 [95%CI 1.03 to 2.14] and performance IQ (OR 1.48 [95%CI 1.08 to 2.04]) but not verbal IQ (OR 1.06 [95%CI 0.69 to 1.64]). Most physical violence occurred postnatally, and relative odds were most substantial when mothers were exposed to violence across pre-/perinatal and postnatal study periods (OR performance IQ<90 = 2.97 [95%CI 1.30 to 6.82]). Conclusions: Maternal exposure to physical IPV is associated with lower offspring IQ at age 8. Associations persisted after adjusting for potential confounders and were driven by violence occurring postnatally.

Instability in longitudinal childhood IQ scores of Guatemalan high SES individuals born between 1941-1953.

Childhood IQ has been used to predict later life outcomes across disciplines in epidemiology, education, and psychology. Most often only a single childhood IQ test is available or is used for these purposes in the belief that IQ is stable across the life course. The primary aim of this study was to examine the longitudinal stability of individuals’ IQ test scores derived from school-age tests. The secondary aim was to investigate the association of the pre-adult scores with later life intelligence scores. The longitudinal pre-adult IQ scores of 42 high socioeconomic status Guatemalans born 1941–1953 were analysed and showed low stability of longitudinal test scores. Fluctuations of >1SD were found for 59.5% of the sample. The same participants, aged 64–76 years, were re-assessed and average pre-adult IQ explained 12% of variance in the older age intelligence score. The reasons behind the longitudinal instability in test scores reported in this study remains unknown but the results suggest single point measurements of intelligence before adulthood should be regarded with some caution.

Organophosphate Pesticide Metabolite Concentrations in Urine during Pregnancy and Offspring Nonverbal IQ at Age 6 Years.

Background:Susceptibility to organophosphate (OP) pesticide neurotoxicity may be greatest during the prenatal period; however, previous studies have produced mixed findings concerning in utero OP pesticide exposure and child cognition.Objectives:Our objective was to determine whether maternal urinary concentrations of OP pesticide metabolites are inversely associated with child nonverbal IQ at 6 y of age and to examine potential effect measure modification by the PON1 gene.Methods:Data came from 708 mother–child pairs participating in the Generation R Study. Maternal urine concentrations of six dialkylphosphates (DAPs), collected at , 18–25, and of gestation, were determined. Child nonverbal IQ was measured at 6 y of age using the Mosaics and Categories subtests from the Snijders-Oomen Nonverbal Intelligence Test–Revised. PON1 was determined in cord blood for 474 infants. Multiple linear regression models were fit to estimate the DAP–IQ associations and PON1 interactions.Results:Overall, associations between child nonverbal IQ and maternal DAP concentrations were small and imprecise, and these associations were inconsistent across urine sampling periods. However, for a 10-fold difference in total DAP concentration for the of gestation samples, adjusted child nonverbal IQ was 3.9 points lower (95% CI: , ). Heterogeneity in the DAP–IQ association by PON1 gene allele status was not observed ().Conclusions:Consistent evidence of an association between higher maternal urinary DAP concentrations and lower child IQ scores at 6 y of age was not observed. There was some evidence for an inverse relation of child nonverbal IQ and late pregnancy urinary DAPs, but the estimated association was imprecise. https://doi.org/10.1289/EHP3024

Pediatric Manganese Exposure and Neurocognition in Eastern Ohio

Manganese (Mn) is both an essential element and neurotoxicant. Two communities in eastern Ohio have the two of the highest ambient Mn concentrations in the nation. Our goal is to address the communities' primary research question: &amp;#8220;Does Mn affect cognitive development of children?&amp;#8221; Children ages 7-9 were enrolled in the Communities Actively Researching Exposure Study (CARES) from Marietta, Cambridge, and East Liverpool, Ohio. CARES has been conducted using community-based participatory research principles. We conducted neurocognitive assessment (child IQ). Blood was analyzed for Mn and lead (Pb); hair were analyzed for Mn, and serum was analyzed for cotinine, a measure of second hand tobacco smoke. We used penalized splines to assess potential non-linear associations between biological measures and child IQ scores, followed by multivariable regression models with categorical variables based on quartiles of the distribution for biological measures. Both low and high Mn concentrations in blood and hair were negatively associated with child IQ scores. There was a negative association between hair Mn and child IQ in East Liverpool children. Serum cotinine was also negatively associated with child cognitive function. Community engagement has enhanced the research process and the translation of study findings for these communities.

PON1 DNA methylation and neurobehavior in Mexican-American children with prenatal organophosphate exposure

PON1 is a multifunctional enzyme involved in oxidative stress and detoxification of some organophosphate (OP) pesticides. It has been associated with nervous system diseases like Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and autism. We previously found that PON1 susceptible genotypes were associated with lower IQ scores in children. Epigenetic marks, such as DNA methylation, can regulate gene expression. Yet, data on whether DNA methylation may influence the relationship between PON1 levels and neurobehavior are limited. In this study, we used Illumina 450K and EPIC BeadChip arrays to assess PON1 DNA methylation in blood specimens collected from children (n = 238) at birth (cord blood) and age 7 years and examined their relationship with cognitive outcomes. The Wechsler Intelligence Scale for Children was used to assess Full Scale IQ and four composite measures (Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed Indexes) in 7-year-old children. We observed a consistent yet nonsignificant inverse relationship of methylation at several CpG sites close to the PON1 transcription start site with Full Scale IQ and other composite measures of cognition. We also found an inverse relationship between cord blood methylation at cg15887283 with working memory and a positive association of 7-year-old methylation at cg22798737 with processing speed, independent of OP exposure. However, none of the associations remained significant after accounting for multiple comparisons. This study provides some evidence of the role DNA methylation may play in the known relationship between PON1 and neurobehavior in children, however it appears to be only suggestive and warrants additional research.

Prenatal Exposure to Perfluoroalkyl Substances and IQ Scores at Age 5; a Study in the Danish National Birth Cohort.

Background:Perfluoroalkyl substances (PFASs) are widespread persistent organic compounds that have been suggested to affect neurodevelopment.Objective:We aimed to evaluate whether prenatal exposure to PFASs is associated with IQ in children.Methods:We studied 1,592 pregnancies enrolled in the Danish National Birth Cohort (DNBC) during 1996–2002. Sixteen PFASs were measured in maternal plasma collected in early gestation. Child IQ was assessed at 5 y of age using the Wechsler Primary and Preschool Scales of Intelligence–Revised (WPPSI-R) administered by trained psychologists. Using multivariable linear regression models, we estimated the differences in child IQ scores according to PFAS concentration [per natural-log (ng/mL) unit increase or values categorized in quartiles].Results:Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were detected in all samples, and five additional PFASs were quantified in of the samples. Overall, we found no strong associations between a natural-log unit increase in each of the seven PFASs we evaluated and child IQ scores. A few positive and negative associations were found in the sex-stratified PFAS quartile analyses, but the patterns were inconsistent.Conclusion:Overall, we did not find consistent evidence to suggest prenatal exposure to PFASs to be associated with child IQ scores at 5 y of age in the DNBC. Some of the sex-specific observations warrant further investigation. Additional studies should examine offspring IQ at older ages and assess other functional cognitive and neuropsychiatric measures in addition to intelligence. Postnatal exposures to PFASs and mixture effects for PFASs and PFASs with other environmental pollutants should also be considered in future research. https://doi.org/10.1289/EHP2754

The mediating role of sleep in the fish consumption \u2013 cognitive functioning relationship: a cohort study

Greater fish consumption is associated with improved cognition among children, but the mediating pathways have not been well delineated. Improved sleep could be a candidate mediator of the fish-cognition relationship. This study assesses whether 1) more frequent fish consumption is associated with less sleep disturbances and higher IQ scores in schoolchildren, 2) such relationships are not accounted for by social and economic confounds, and 3) sleep quality mediates the fish-IQ relationship. In this cohort study of 541 Chinese schoolchildren, fish consumption and sleep quality were assessed at age 9–11 years, while IQ was assessed at age 12. Frequent fish consumption was related to both fewer sleep problems and higher IQ scores. A dose-response relationship indicated higher IQ scores in children who always (4.80 points) or sometimes (3.31 points) consumed fish, compared to those who rarely ate fish (all p < 0.05). Sleep quality partially mediated the relationship between fish consumption and verbal, but not performance, IQ. Findings were robust after controlling for multiple sociodemographic covariates. To our knowledge, this is the first study to indicate that frequent fish consumption may help reduce sleep problems (better sleep quality), which may in turn benefit long-term cognitive functioning in children.

Are WISC IQ scores in children with mathematical learning disabilities underestimated? The influence of a specialized intervention on test performance

BackgroundIntelligence measures play a pivotal role in the diagnosis of mathematical learning disabilities (MLD). Probably as a result of math-related material in IQ tests, children with MLD often display reduced IQ scores. However, it remains unclear whether the effects of math remediation extend to IQ scores. AimsThe present study investigated the impact of a special remediation program compared to a control group receiving private tutoring (PT) on the WISC IQ scores of children with MLD. MethodsWe included N=45 MLD children (7–12 years) in a study with a pre- and post-test control group design. Children received remediation for two years on average. ResultsThe analyses revealed significantly greater improvements in the experimental group on the Full-Scale IQ, and the Verbal Comprehension, Perceptual Reasoning, and Working Memory indices, but not Processing Speed, compared to the PT group. Children in the experimental group showed an average WISC IQ gain of more than ten points. ConclusionResults indicate that the WISC IQ scores of MLD children might be underestimated and that an effective math intervention can improve WISC IQ test performance. Taking limitations into account, we discuss the use of IQ measures more generally for defining MLD in research and practice.

The Role of Paternal Age in the Prediction of Offspring Intelligence

ABSTRACTRecent evidence suggests that paternal age at birth influences myriad developmental outcomes among children, but few studies have examined the possibility for father's age to influence children's intellectual development among a sample of high-risk families. The authors use data from the Fragile Families and Child Wellbeing Study to examine the association between paternal age at birth among 480 male and 449 female children's verbal IQ scores, as assessed with a version of the Peabody Picture Vocabulary Test at 9 years old. The nonlinear association between paternal age and children's verbal intelligence was also examined. Paternal age at birth appears to have a marginally significant nonlinear relationship with male children's verbal IQ scores, despite controlling for a number of possible confounders associated with both young and advanced paternal age.

In Memoriam: Herbert L. Needleman

In Memoriam: Herbert L. Needleman

Impact of air manganese on child neurodevelopment in East Liverpool, Ohio

BackgroundEast Liverpool, Ohio, the site of a hazardous waste incinerator and a manganese (Mn) processor, has had air Mn concentrations exceeding United States Environmental Protection Agency reference levels for over a decade. Save Our County, Inc., a community organization, was formed to address community environmental health concerns related to local industry. Researchers from the University of Cincinnati partnered with Save Our County to determine if air Mn had an impact on the neurocognitive function of children in the community. MethodsChildren 7–9 years of age from East Liverpool and its surrounding communities, were enrolled (N=106) in the Communities Actively Researching Exposure Study from between March 2013–June 2014. Blood and hair were analyzed for Mn and lead, and serum was analyzed for cotinine. We used linear regression to assess associations between biological measures and IQ subscale scores. ResultsGeometric mean blood lead (n=67), blood Mn (n=66), hair Mn (n=98), and serum cotinine (n=69) concentrations were 1.13±1.96μg/dL, 10.06±1.30μg/L, and 360.22±2.17ng/g, 0.76±6.12μg/L respectively. After adjusting for potential confounders, hair Mn was negatively associated with Full Scale IQ. ConclusionsHair Mn was negatively associated with child IQ scores. Community partners were instrumental in the conception and implementation of this study.

Linking the Standard and Advanced Raven Progressive Matrices tests to model intelligence covariance in twin families

An abundance of research shows significant resemblance in standardized IQ scores in children and their biological parents. Twin and family studies based on such standardized scores suggest that a large proportion of the resemblance is due to genetic transmission, rather than cultural transmission. However, most studies used standardized intelligence scores that were based on different tests for different age groups, which makes it hard to say if the exact same construct is measured. Here we re-analyze intelligence data on two different versions of the Raven Progressive Matrices test, collected in Dutch twin children (Standard test version) and their biological parents (Advanced test version). First, the data from parents and their offspring were harmonized using test linking through an item response theory measurement model. This required collecting data from extra participants who were assessed with items from both test versions. Next, the raw item data were analyzed to study transmission of intelligence, correcting for the differences in difficulty of the items in the parental and child test versions and differences in measurement reliability. Results showed a significant difference in the phenotypic variance in intelligence in the two generations. Model fitting showed that the surplus variance in the parental generation is likely due to surplus environmental variance that is not transmitted to the offspring. This could reflect that there was extra measurement error under the parental testing conditions. Genetic modelling showed that intelligence covariance in parents and their children is most likely based on genetic transmission without cultural transmission.