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INTRODUCTION: To date, the evidence for an association between perfluoroalkyl substances (PFAS) exposure and attention deficit and hyperactivity disorder (ADHD) is inconclusive. OBJECTIVE: We investigated the association between early life exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), and ADHD in a collaborative study including nine European population-based studies, encompassing 4,826 mother-child pairs. METHODS: Concentrations of PFOS and PFOA were measured in maternal serum/plasma during pregnancy, or in breast milk, with different timing of sample collection in each cohort. We used a validated pharmacokinetic model of pregnancy and lactation to estimate concentrations of PFOS and PFOA in children at birth and at 3, 6, 12, and 24 months of age. We classified ADHD using recommended cutoff points for each instrument used to derive symptoms scores. We used multiple imputation for missing covariates, logistic regression to model the association between PFAS exposure and ADHD in each study, and combined all adjusted study-specific effect estimates using random-effects meta-analysis. RESULTS: A total of 399 children were classified as having ADHD, with a prevalence ranging from 2.3% to 7.3% in the studies. Early life exposure to PFOS or PFOA was not associated with ADHD during childhood [odds ratios (ORs) ranging from 0.96 (95% CI: 0.87, 1.06) to 1.02 (95% CI: 0.93, 1.11)]. Results from stratified models suggest potential differential effects of PFAS related to child sex and maternal education. CONCLUSION: We did not identify an increased prevalence of ADHD in association with early life exposure to PFOS and PFOA. However, stratified analyses suggest that there may be an increased prevalence of ADHD in association with PFAS exposure in girls, in children from nulliparous women, and in children from low-educated mothers, all of which warrant further exploration. https://doi.org/10.1289/EHP5444, Introduction Attention deficit hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder during childhood. The global prevalence of ADHD in the population younger than 18 years of age has been [...]

Background: Vulnerability of the central nervous system to mercury exposure is increased during early development. The aim of this study is to evaluate the association between prenatal exposure to mercury and child neuropsychological development in high-fish-intake areas in Spain.Methods: Study subjects were 1362 children, participants in the INMA (Environment and Childhood) birth cohort study. Cord blood total mercury (CB-Hg) and cord polyunsaturated fatty acids (PUFA) concentrations were analysed in samples collected between 2004 and 2008. Child neuropsychological development was assessed at age 4-5 years by the McCarthy Scales of Children's Abilities (MSCA). Socio-demographic, lifestyle and dietary information was obtained by questionnaires administered during pregnancy and childhood.Results: The geometric mean of CB-Hg was 8.8 µg/L [95% confidence interval (CI) 8.4, 9.2]. A doubling in CB-Hg was associated with higher scores in most of the MSCA scales ( β =1.29; 95% CI 0.28, 2.31 for the general cognitive scale). The association between CB-Hg and the scores obtained on the scales was inverse among children whose mothers consumed fewer than three weekly servings of fish during the first trimester of pregnancy, although confidence intervals did not exclude the null ( β =-1.20; 95% CI -2.62, 0.22 for the perceptive-manipulative scale and β =-3.06; 95% CI -6.37, 0.24 for the general cognitive scale). An inverse association between CB-Hg and the scores on the motor scale was also suggested for children with an n-6/n-3 PUFA ratio above the median ( β =-0.23; 95% CI -0.87, 0.40, interaction p -value=0.03).Conclusion: The relationship between CB-Hg concentrations and child neuropsychological development was influenced by maternal nutritional factors, such as fish consumption and the PUFA status. [ABSTRACT FROM AUTHOR]

Background: Prospective longitudinal studies are essential in characterizing cognitive trajectories, yet few of them have been reported on the development of attention processes in children. We aimed to explore attention development in normal children and children with attention deficit and hyperactivity disorder (ADHD) symptoms in a repeated measures design using the attention network test (ANT). Methods: The population sample included 2,835 children (49.6% girls) aged 7-11 years from 39 schools in Barcelona (Catalonia, Spain) who performed the ANT four times from January 2012 to March 2013. According to teacher ratings, 10.5% of the children presented ADHD symptoms. We performed multilevel mixed-effects linear regression models, adjusting for school and individual, to test the effects of age-related growth on the ANT networks: alerting, orienting and executive attention, and three measurements related to attentiveness: median of hit reaction time (HRT), hit reaction time standard error (HRT-SE) and variability. Results: We observed age-related growth in all the outcomes, except orienting. The curves were steeper at the younger groups, although for alertness the improvement was further at the oldest ages. Gender and ADHD symptoms interacted with age in executive attention, HRT and variability. Girls performed better in executive attention at young ages although boys reached females at around 10 years of age. For HRT, males showed faster HRT. However, girls had a more pronounced improvement and reached the levels of boys at age 11. Children with ADHD symptoms had significant differences in executive attention, HRT and variability compared to children without ADHD symptoms. Conclusions: We detected an ongoing development of some aspects of attention in primary school children, differentiating patterns by gender and ADHD symptoms. Our findings support the ANT for assessing attention processes in children in large epidemiological studies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Exposure to traffic noise has been associated with adverse effects on neuro-psychological outcomes in children, but findings with regard to behavioral problems are inconsistent. OBJECTIVE: We investigated whether residential road traffic noise exposure is associated with behavioral problems in 7-year-old children. METHODS: We identified 46,940 children from the Danish National Birth Cohort with complete information on behavioral problems at 7 years of age and complete address history from conception to 7 years of age. Road traffic noise (Lden) was modeled at all present and historical addresses. Behavioral problems were assessed by the parent-reported Strengths and Difficulties Questionnaire (SDQ). Associations between pregnancy and childhood exposure to noise and behavioral problems were analyzed by multinomial or logistic regression and adjusted for potential confounders. RESULTS: A 10-dB increase in average time-weighted road traffic noise exposure from birth to 7 years of age was associated with a 7% increase (95% CI: 1.00, 1.14) in abnormal versus normal total difficulties scores; 5% (95% CI: 1.00, 1.10) and 9% (95% CI: 1.03, 1.18) increases in borderline and abnormal hyperactivity/inattention subscale scores, respectively; and 5% (95% CI: 0.98, 1.14) and 6% (95% CI: 0.99, 1.12) increases in abnormal conduct problem and peer relationship problem subscale scores, respectively. Exposure to road traffic noise during pregnancy was not associated with child behavioral problems at 7 years of age. CONCLUSIONS: Residential road traffic noise in early childhood may be associated with behavioral problems, particularly hyperactivity/inattention symptoms. [ABSTRACT FROM AUTHOR]

Background: Green spaces have been associated with improved mental health in children; however, available epidemiological evidence on their impact on child behavioral development is scarce. Objectives: We investigated the impact of contact with green spaces and blue spaces (beaches) on indicators of behavioral development and symptoms of attention deficit/hyperactivity disorder (ADHD) in schoolchildren. Methods: This study was based on a sample of 2,111 schoolchildren (7–10 years of age) from 36 schools in Barcelona in 2012. We obtained data on time spent in green spaces and beaches and Strengths and Difficulties Questionnaires (SDQ) from parents, and ADHD/DSM-IV questionnaires from teachers. Surrounding greenness was abstracted as the average Normalized Difference Vegetation Index (NDVI) in buffers of 100 m, 250 m, and 500 m around each home address. Proximity to green spaces was defined as living within 300 m of a major green space (≥ 0.05 km2). We applied quasi-Poisson mixed-effects models (with school random effect) to separately estimate associations between indicators of contact with green spaces and SDQ and ADHD total and subscale scores. Results: We generally estimated beneficial associations between behavioral indicators and longer time spent in green spaces and beaches, and with residential surrounding greenness. Specifically, we found statistically significant inverse associations between green space playing time and SDQ total difficulties, emotional symptoms, and peer relationship problems; between residential surrounding greenness and SDQ total difficulties and hyperactivity/inattention and ADHD/DSM-IV total and inattention scores; and between annual beach attendance and SDQ total difficulties, peer relationship problems, and prosocial behavior. For proximity to major green spaces, the results were not conclusive. Conclusion: Our findings support beneficial impacts of contact with green and blue spaces on behavioral development in schoolchildren. [ABSTRACT FROM AUTHOR]

Exposure to highly elevated levels of cortisol has been linked with impairments in cognitive capacities in both children and adults. By contrast, moderate levels of cortisol may engender beneficial effects. The main aim of this study was to assess the association between child cortisol levels and neuropsychological development during the second year of life. A population-based birth cohort was established in the city of Sabadell (Catalonia, Spain) as part of the INMA (Environment and Childhood) Project. We assessed the cognitive and psychomotor development at the age of 14 months using the Bayley Scales of Infant Development (BSID). We included 302 children assessed during their second year of life for whom we had information on neuropsychological assessment and measurements of cortisol in saliva. Higher levels of cortisol were associated with better scores in BSID's mental scale. There was no association between cortisol levels and psychomotor test scores. We found a small positive association between duration of breastfeeding and child cortisol levels. This association was only found in boys. The results of this study suggest that moderate levels of cortisol in children could have small beneficial effects on their early neuropsychological development. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is increasing interest in the potential effects of polybrominated diphenyl ethers (PBDEs) on children's neuropsychological development, but only a few small studies have evaluated such effects. OBJECTIVES: Our goal was to examine the association between PBDE concentrations in colostrum and infant neuropsychological development and to assess the influence of other persistent organic pollutants (POPs) on such association. METHODS: We measured concentrations of PBDEs and other POPs in colostrum samples of 290 women recruited in a Spanish birth cohort. We tested children for mental and psychomotor development with the Bayley Scales of Infant Development at 12-18 months of age. We analyzed the sum of the seven most common PBDE congeners (BDEs 47, 99, 100, 153, 154, 183, 209) and each congener separately. RESULTS: Increasing Σ[sub 7]PBDEs concentrations showed an association of borderline statistical significance with decreasing mental development scores (Βper log ng/g lipid = -- 2.25; 95% CI: -4.75, 0.26). BDE-209, the congener present in highest concentrations, appeared to be the main congener responsible for this association (Β= -- 2.40, 95% CI: -4.79, -- 0.01). There was little evidence for an association with psychomotor development. After adjustment for other POPs, the BDE-209 association with mental development score became slightly weaker (Β= -- 2.10, 95% CI: -4.66, 0.46). CONCLUSIONS: Our findings suggest an association between increasing PBDE concentrations in colostrum and a worse infant mental development, particularly for BDE-209, but require confirmation in larger studies. The association, if causal, may be due to unmeasured BDE-209 metabolites, including OH-PBDEs (hydroxylated PBDEs), which are more toxic, more stable, and more likely to cross the placenta and to easily reach the brain than BDE-209. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the role of extracurricular physical activity and sedentary behavior at preschool and primary school age on working memory at primary school age and adolescence, respectively.Study Design: This prospective study was based on a birth cohort across 4 Spanish regions. In the 3 younger subcohorts (n = 1093), parents reported lifestyle habits of child at age 4 years of age on a questionnaire, and children performed a computerized working memory task at 7 years of age. In the older subcohort (n = 307), the questionnaire was completed at 6 years of age and working memory was tested at 14 years of age. Adjusted regression models were developed to investigate the associations between lifestyle habits and working memory.Results: Low extracurricular physical activity levels at 4 years of age were associated with a nonsignificant 0.95% (95% CI -2.81 to 0.92) reduction of correct responses in the working memory task at age 7 years of age. Low extracurricular physical activity levels at 6 years of age were associated with a 4.22% (95% CI -8.05 to -0.39) reduction of correct responses at age 14 years. Television watching was not associated with working memory. Other sedentary behaviors at 6 year of age were associated with a 5.07% (95% CI -9.68 to -0.46) reduction of correct responses in boys at 14 years of age.Conclusion: Low extracurricular physical activity levels at preschool and primary school ages were associated with poorer working memory performance at primary school age and adolescence, respectively. High sedentary behavior levels at primary school age were related negatively to working memory in adolescent boys. [ABSTRACT FROM AUTHOR]

There is inconsistent evidence regarding the effects of prenatal phthalate exposure on children's neuropsychological development. We evaluate the association between prenatal phthalate exposure and the cognitive, psychomotor and behavioral development of 367 children at repeated ages in a prospective birth cohort study. We measured phthalate metabolites (sum of four DEHP metabolites – Σ 4 DEHP, MBzP, MEP, MiBP and MnBP) in urine samples collected during the 1st and 3rd trimesters of pregnancy in women participating in the INMA-Sabadell birth cohort study. We assessed cognitive and psychomotor development of their children at 1 and 4 years, and social competence, ADHD symptoms and other behavioral problems at 4 and 7 years. No associations were observed between prenatal phthalate exposure and cognitive and psychomotor scores at the age of 1 year and at the age of 4 years, except for an association between MBzP and lower psychomotor scores ( β = −1.49 [95% confidence interval (CI) = −2.78, −0.21]). Σ 4 DEHP concentrations were associated with increased social competence scores at 4 years and with reduced ADHD symptoms at age 4 and 7 years. Increasing MEP concentrations were associated with a reduced risk of inattention symptoms at 4 years. No associations were observed for MBzP, MiBP or MnBP in relation to behavioral problems. This study, with multiple phthalate exposure measurements and measures of neuropsychological domains at different ages, suggest that prenatal phthalate exposure does not adversely affect children's cognitive, psychomotor or behavioral development. [ABSTRACT FROM AUTHOR]

Air pollution (AP) may affect neurodevelopment, but studies about the effects of AP on the growing human brain are still scarce. We aimed to investigate the effects of prenatal exposure to AP on lateral ventricles (LV) and corpus callosum (CC) volumes in children and to determine whether the induced brain changes are associated with behavioral problems. Among the children recruited through a set of representative schools of the city of Barcelona, (Spain) in the Brain Development and Air Pollution Ultrafine Particles in School Children (BREATHE) study, 186 typically developing participants aged 8–12 years underwent brain MRI on the same 1.5 T MR unit over a 1.5-year period (October 2012–April 2014). Brain volumes were derived from structural MRI scans using automated tissue segmentation. Behavioral problems were assessed using the Strengths and Difficulties Questionnaire (SDQ) and the criteria of the Attention Deficit Hyperactivity Disorder DSM-IV list. Prenatal fine particle (PM 2.5) levels were retrospectively estimated at the mothers' residential addresses during pregnancy with land use regression (LUR) models. To determine whether brain structures might be affected by prenatal PM 2.5 exposure, linear regression models were run and adjusted for age, sex, intracranial volume (ICV), maternal education, home socioeconomic vulnerability index, birthweight and mothers' smoking status during pregnancy. To test for associations between brain changes and behavioral outcomes, negative binomial regressions were performed and adjusted for age, sex, ICV. Prenatal PM 2.5 levels ranged from 11.8 to 39.5 μg/m3 during the third trimester of pregnancy. An interquartile range increase in PM 2.5 level (7 μg/m3) was significantly linked to a decrease in the body CC volume (mm3) (β = −53.7, 95%CI [-92.0, −15.5] corresponding to a 5% decrease of the mean body CC volume) independently of ICV, age, sex, maternal education, socioeconomic vulnerability index at home, birthweight and mothers' smoking status during the third trimester of pregnancy. A 50 mm3 decrease in the body CC was associated with a significant higher hyperactivity subscore (Rate Ratio (RR) = 1.09, 95%CI [1.01, 1.17) independently of age, sex and ICV. The statistical significance of these results did not survive to False Discovery Rate correction for multiple comparisons. Prenatal exposure to PM 2.5 may be associated with CC volume decrease in children. The consequences might be an increase in behavioral problems. • We examined the effects of prenatal exposure to PM 2.5 on the children's brain volumes. • Increase in PM 2.5 levels was associated to a decrease in the corpus callosum volume. • This air pollution-related volume decrease may be associated to behavioral problems. [ABSTRACT FROM AUTHOR]