Early life predictors of childhood intelligence: findings from the Mater-University study of pregnancy and its outcomes

Evaluation of genomic factors and early childhood stimulation on intelligence in children from a Brazilian birth cohort: The primary role of independent factors

BACKGROUND

Childhood cognitive abilities are a predictor of health outcomes and adult income potential. Identifying factors associated with childhood intelligence and their interactions is essential in behavioral research. We assessed the impact of genetic variants and early child stimulation (ECS) on child intelligence and examined their possible interaction as potential modifiers of IQ in a population-based longitudinal study.

METHODS

Participants of the 2004 Pelotas Birth Cohort study (N = 4231) underwent intelligent quotient (IQ) by WISC-III assessment at 6 years of age. At 24 and 48-months, mothers answered five ECS marker questions, whose sum was used to create a score. The polygenic score for intelligence (IQ-PGS) was constructed from the GWAS-weighted estimate of cognition. Association was assessed using multiple linear regression models adjusted for maternal, family, and child confounding variables. To explore the possible influence of skin color and ethnoracial classification, the regression models were stratified according to the skin color variable, as a sensitivity analysis.

RESULTS

In the adjusted analysis, IQ-PGS (β = 0.79, 95% confidence interval [95% CI] 0.26;1.31) as well as ECS (β = 2.34; 95% CI: 1.76;2.92) were associated with IQ in this sample. The association between IQ-PGS and IQ was significant only in the white Brazilian group in the sensitivity analysis. However, there was no interaction between IQ-PGS and ECS on IQ (p(IQ-PGS x ECS) = 0.46).

CONCLUSIONS

ECS did not modify the impact of genetic potential on intellectual development during childhood, suggesting that genetic factors and ECS exert independent effects on the IQ levels of children.

Assessing harmonized intelligence measures in a multinational study

Studies examining the neurocognitive and circuit-based etiology of psychiatric illness are moving toward inclusive, global designs. A potential confounding effect of these associations is general intelligence; however, an internationally validated, harmonized intelligence quotient (IQ) measure is not available. We describe the procedures used to measure IQ across a five-site, multinational study and demonstrate the harmonized measure's cross-site validity. Culturally appropriate intelligence measures were selected: four short-form Wechsler intelligence tests (Brazil, Netherlands, South Africa, United States) and the Binet Kamat (India). Analyses included IQ scores from 255 healthy participants (age 18-50; 42% male). Regression analyses tested between-site differences in IQ scores, as well as expected associations with sociodemographic factors (sex, socioeconomic status, education) to assess validity. Harmonization (e.g., a priori selection of tests) yielded the compatibility of IQ measures. Higher IQ was associated with higher socioeconomic status, suggesting good convergent validity. No association was found between sex and IQ at any site, suggesting good discriminant validity. Associations between higher IQ and higher years of education were found at all sites except the United States. Harmonized IQ scores provide a measure of IQ with evidence of good validity that can be used in neurocognitive and circuit-based studies to control for intelligence across global sites.

Intelligence-Dependent Differential Effects of Media Exposure on Executive Function Changes in Children: A Population-Based Cohort Study With a Longitudinal Design

BACKGROUND

Excessive media use is known to be associated with executive dysfunction in children, but it's unclear whether this exposure can lead to long-term changes of executive function. This study aimed to investigate the association between media exposure and longitudinal changes in executive function within a population-based study, while considering the potential influence of intelligence.

METHODS

This study used data from 1,209 participants in the Panel Korea Study for Children. The children's media exposure was measured at ages 7 and 8, and executive function was evaluated annually from ages 7 to 10 using the Executive Function Difficulty Screening Questionnaire. Participants were grouped by media exposure level (low, medium, or high), and longitudinal changes in executive function were analyzed using linear mixed effects models. Subgroup analysis was conducted to investigate how executive function changes varied based on intelligence within each media exposure group.

RESULTS

Children with high media exposure (n = 97) had severer executive function difficulties than those with low (n = 141) or medium (n = 971) exposure in all waves. The high exposure group demonstrated persistent higher executive function difficulties up to age 10 after controlling for child gender, intelligence, parental education level and maternal depression. Children with intelligence quotient (IQ) ≤ 100 in the medium to high media exposure group had significantly more severe executive function difficulties than those with IQ > 100.

CONCLUSION

This study provided evidence of a longitudinal negative association between media exposure and executive function. The findings suggest that excessive media exposure may lead to long-term changes in executive function in children and highlight the importance of implementing targeted interventions and educational strategies to mitigate the potential negative effects of excessive media use, particularly for children with lower cognitive abilities.

Breastfeeding is associated with the intelligence of school-age children in Mexico

Breastfeeding has been consistently associated with higher intelligence since childhood. However, this relation could be confounded due to maternal selection bias. We estimated the association between predominant breastfeeding and intelligence in school-age children considering potential selection bias and we simulated the intelligence gap reduction between low versus higher socioeconomic status children by increasing breastfeeding. We analysed predominant breastfeeding practices (breastmilk and water-based liquids) of children 0-3 years included in the Mexican Family Life Survey (MxFLS-1). Intelligence was estimated as the z-score of the abbreviated Raven score, measured at 6-12 years in the MxFLS-2 or MxFLS-3. We predicted breastfeeding duration among children with censored data with a Poisson model. We used the Heckman selection model to assess the association between breastfeeding and intelligence, correcting for selection bias and stratified by socioeconomic status. Results show after controlling for selection bias, a 1-month increase in predominant breastfeeding duration was associated with a 0.02 SD increase in the Raven z-score (p < 0.05). The children who were predominantly breastfed for 4-6 months versus <1 month had 0.16 SD higher Raven z-score (p < 0.05). No associations were found using multiple linear regression models. Among low socioeconomic status children, increasing predominantly breastfeeding duration to 6 months would increase their mean Raven z-score from -0.14 to -0.07 SD and reduce by 12.5% the intelligence gap with high socioeconomic status children. In conclusion, predominant breastfeeding duration was significantly associated with childhood intelligence after controlling for maternal selection bias. Increased breastfeeding duration may reduce poverty-driven intelligence inequities.

Big data, machine learning, and population health: predicting cognitive outcomes in childhood

The application of machine learning (ML) to address population health challenges has received much less attention than its application in the clinical setting. One such challenge is addressing disparities in early childhood cognitive development-a complex public health issue rooted in the social determinants of health, exacerbated by inequity, characterised by intergenerational transmission, and which will continue unabated without novel approaches to address it. Early life, the period of optimal neuroplasticity, presents a window of opportunity for early intervention to improve cognitive development. Unfortunately for many, this window will be missed, and intervention may never occur or occur only when overt signs of cognitive delay manifest. In this review, we explore the potential value of ML and big data analysis in the early identification of children at risk for poor cognitive outcome, an area where there is an apparent dearth of research. We compare and contrast traditional statistical methods with ML approaches, provide examples of how ML has been used to date in the field of neurodevelopmental disorders, and present a discussion of the opportunities and risks associated with its use at a population level. The review concludes by highlighting potential directions for future research in this area. IMPACT: To date, the application of machine learning to address population health challenges in paediatrics lags behind other clinical applications. This review provides an overview of the public health challenge we face in addressing disparities in childhood cognitive development and focuses on the cornerstone of early intervention. Recent advances in our ability to collect large volumes of data, and in analytic capabilities, provide a potential opportunity to improve current practices in this field. This review explores the potential role of machine learning and big data analysis in the early identification of children at risk for poor cognitive outcomes.

In-utero exposure to indoor air pollution or tobacco smoke and cognitive development in a South African birth cohort study

BACKGROUND AND AIMS

There is increasing evidence indicating that air pollution exposure is associated with neuronal damage. Since pregnancy is a critical window of vulnerability, air pollution exposure during this period could have adverse effects on neurodevelopment. This study aims 1) to analyze associations of prenatal exposure to indoor air pollution (particulate matter with diameters ≤10 μm, PM10) and tobacco smoke with neurodevelopment and 2) to determine whether these associations are mediated by deviations of epigenetic gestational age from chronological gestational age (ΔGA).

METHODS

Data of 734 children from the South African Drakenstein Child Health Study were analyzed. Prenatal PM10 exposure was measured using devices placed in the families' homes. Maternal smoking during pregnancy was determined by maternal urine cotinine measures. The Bayley Scales of Infant and Toddler Development III (BSID-III) was used to measure cognition, language and motor development and adaptive behavior at two years of age. Linear regression models adjusted for maternal age, gestational age, sex of child, ancestry, birth weight/length, and socioeconomic status were used to explore associations between air pollutants and BSID-III scores. A mediation analysis was conducted to analyze if these associations were mediated by ΔGA using DNA methylation measurements from cord blood.

RESULTS

An increase of one interquartile range in natural-log transformed PM10 (lnPM10; 1.58 μg/m3) was significantly associated with lower composite scores in cognition, language, and adaptive behavior sub-scores (composite score β-estimate [95%-confidence interval]: -0.950 [-1.821, -0.120]). Maternal smoking was significantly associated with lower adaptive behavior scores (-3.386 [-5.632, -1.139]). Associations were not significantly mediated by ΔGA (e.g., for PM10 and cognition, proportion mediated [p-value]: 4% [0.52]).

CONCLUSION

We found an association of prenatal exposure to indoor air pollution (PM10) and tobacco smoke on neurodevelopment at two years of age, particularly cognition, language, and adaptive behavior. Further research is needed to understand underlying biological mediators.

Five-minute Apgar score and outcomes in neonates of 24-28 weeks' gestation

OBJECTIVES

To assess associations between 5 min Apgar score and mortality and severe neurological injury (SNI) and to report test characteristics in preterm neonates.

DESIGN, SETTING AND PATIENTS

Retrospective cohort study of neonates 24⁰ to 28⁶ weeks' gestation born between 2007 and 2016 and admitted to neonatal units in 11 high-income countries.

EXPOSURE

5 min Apgar score.

MAIN OUTCOME MEASURES

In-hospital mortality and SNI defined as grade 3 or 4 periventricular/intraventricular haemorrhage or periventricular leukomalacia. Outcome rates were calculated for each Apgar score and compared after adjustment. The diagnostic characteristics and ORs for each value from 0 versus 1-10 to 0-9 versus 10, with 1-point increments were calculated.

RESULTS

Among 92 412 included neonates, as 5 min Apgar score increased from 0 to 10, mortality decreased from 60% to 8%. However, no clear increasing or decreasing pattern was identified for SNI. There was an increase in sensitivity and decrease in specificity for both mortality and SNI associated with increasing scores. The Apgar score alone had an area under the curve of 0.64 for predicting mortality, which increased to 0.73 with the addition of gestational age.

CONCLUSIONS

In neonates of 24-28 weeks' gestation admitted to neonatal units, higher 5 min Apgar score was associated with lower mortality in a graded manner, while the association with SNI remained relatively constant at all scores. Among survivors, low Apgar scores did not predict SNI.

Maternal smoking during pregnancy and intelligence quotient of offspring aged 18 and 30 years: Evidence from two birth cohorts in southern Brazil

Maternal smoking during pregnancy causes several harmful effects, including deficits in the intelligence quotient (IQ), a measure associated with academic achievements and higher socioeconomic position. We aimed to measure the association between maternal smoking during pregnancy and offspring's IQ in two birth cohorts from Pelotas, Brazil. Data from the 1982 and 1993 birth cohorts were analyzed. Smoking during pregnancy was ascertained at the perinatal follow-up, and IQ was measured at 30 years (1982) and 18 years (1993). Simple and multiple linear regressions were used for crude and adjusted analysis. Mediation analysis was performed using birth weight and breastfeeding as possible mediators. Data analysis was conducted in 2020. There were 3611 and 4050 participants from the 1982 and 1993 cohorts, respectively. After adjustment for potential confounders, the inverse association between smoking during pregnancy and children's IQ remained significant in both cohorts. Offspring of mothers who smoked during pregnancy had an average of 1.32 less IQ points (95%CI: -2.23, -0.242) in the 1982 cohort, and an average of 1.66 less IQ points (95%CI: -2.42, -0.90) in the 1993 cohort. Neither cohort showed association with paternal smoking (negative controls) after adjustment. Breastfeeding's mediated effects accounted for 26.2% and 23.9% of the association in the 1982 and 1993 cohorts, respectively, while birth weight's accounted for 6.8% and 30.1%, respectively; indirect effects were not significant. The inverse association between maternal smoking and IQ and the lack of association with paternal smoking reinforces our findings of a negative association between exposure and outcome.

Prenatal urinary metabolites of polycyclic aromatic hydrocarbons and toddler cognition, language, and behavior

BACKGROUND

Animal and epidemiological studies suggest that prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) may negatively impact toddler neurodevelopment.

METHODS

We investigated this association in 835 mother-child pairs from CANDLE, a diverse pregnancy cohort in the mid-South region of the U.S. PAH metabolite concentrations were measured in mid-pregnancy maternal urine. Cognitive and Language composite scores at ages 2 and 3 years were derived from the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-3). Behavior Problem and Competence scores at age 2 were derived from the Brief Infant and Toddler Social Emotional Assessment (BITSEA). We used multivariate linear or Poisson regression to estimate associations with continuous scores and relative risks (RR) of neurodevelopment delay or behavior problems per 2-fold increase in PAH, adjusted for maternal health, nutrition, and socioeconomic status. Secondary analyses investigated associations with PAH mixture using Weighted Quantile Sum Regression (WQS) with a permutation test extension.

RESULTS

1- hydroxypyrene was associated with elevated relative risk for Neurodevelopmental Delay at age 2 (RR = 1.20, 95% CI: 1.03,1.39). Contrary to hypotheses, 1-hydroxynaphthalene was associated with lower risk for Behavior Problems at age 2 (RR = 0.90, 95% CI: 0.83,0.98), and combined 1- and 9-hydroxyphenanthrene was associated with 0.52-point higher (95% CI: 0.11,0.93) Cognitive score at age 3. For PAH mixtures, a quintile increase in hydroxy-PAH mixture was associated with lower Language score at age 2 (βwqs = -1.59; 95% CI: -2.84, -0.34; p_permutation = 0.07) and higher Cognitive score at age 3 (βwqs = 0.96; 95% CI: 0.11, 1.82; p_permutation = 0.05). All other estimates were consistent with null associations.

CONCLUSION

In this large southern U.S. population we observed some support for adverse associations between PAHs and neurodevelopment.

Prenatal and Childhood Immuno-Metabolic Risk Factors for Adult Depression and Psychosis

Depression and psychosis have a developmental component to their origin. Epidemiologic evidence, which we synthesize in this nonsystematic review, suggests that early-life infection, inflammation, and metabolic alterations could play a role in the etiology of these psychiatric disorders. The risk of depression and psychosis is associated with prenatal maternal and childhood infections, which could be mediated by impaired neurodevelopment. Evidence suggests linear dose-response associations between elevated concentrations of circulating inflammatory markers in childhood, particularly the inflammatory cytokine interleukin 6, and the risk for depression and psychosis subsequently in early adulthood. Childhood inflammatory markers are also associated with persistence of depressive symptoms subsequently in adolescence and early adulthood. Developmental trajectories reflecting persistently high insulin levels during childhood and adolescence are associated with a higher risk of psychosis in adulthood, whereas increased adiposity during and after puberty is associated with the risk of depression. Together, these findings suggest that higher levels of infection, inflammation, and metabolic alterations commonly seen in people with depression and psychosis could be a cause for, rather than simply a consequence of, these disorders. Therefore, early-life immuno-metabolic alterations, as well as factors influencing these alterations such as adversity or maltreatment, could represent targets for prevention of these psychiatric disorders. Inflammation could also be an important treatment target for depression and psychosis. The field requires further research to examine sensitive periods when exposure to such immuno-metabolic alterations is most harmful. Interventional studies are also needed to test the potential usefulness of targeting early-life immuno-metabolic alterations for preventing adult depression and psychosis.

Below Average Cognitive Ability-An under Researched Risk Factor for Emotional-Behavioural Difficulties in Childhood

Children with below average cognitive ability represent a substantial yet under-researched population for whom cognitive and social demands, which increase in complexity year by year, may pose significant challenges. This observational study examines the longitudinal relationship between early cognitive ability and emotional-behavioral difficulties (EBDs) between the age of three and nine. Participants include 7134 children from the population-based cohort study growing up in Ireland. Cognitive ability was measured at age three using the Picture Similarities Scale. A t-score one to two standard deviations below the mean was defined as below average cognitive ability (n = 767). EBDs were measured using the Strengths and Difficulties Questionnaire (SDQ) at three, five, and nine years of age. Generalized linear mixed models and logistic regression were used to examine the relationship. Below average cognitive ability was an independent predictor of higher longitudinal SDQ scores. After adjustment, children with below average cognitive ability were 1.39 times more likely (AOR 1.39, 95% CI 1.17–1.66, p < 0.001) to experience a clinically significant EBD between the ages of three to nine years. This study demonstrates the increased risk of EBDs for children with below average cognitive ability. A scalable method of early identification of at-risk children should be a research priority for public health, enabling early intervention for cognitive and adaptive outcomes.

Maternal drinking behaviour and co-exposure from smoking during and after pregnancy in relation to the neurocognitive function of school-children in the rural Western Cape

BACKGROUND

Maternal substance use and its long-term effect on the neurocognitive functions of children is a global public health issue. Despite an increase in substance use in rural areas of low to middle-income countries, research is limited in these populations.

OBJECTIVE

We have therefore explored the effect of maternal drinking and smoking behaviors on the neurocognitive functioning of rural school children.

METHOD

A cross-sectional analysis on the determinants of current, past and gestational maternal alcohol use and gestational smoking on child neurocognitive functions was conducted on school-children (N = 482), embedded within the child health agricultural cohort (CapSA) study across seven schools in rural Western Cape, South Africa. Standardised neurocognitive assessment tools included the Cambridge Automated Neuropsychological Battery (CANTAB) and the KIDSCREEN-10 to measure health-related quality of life via a child questionnaire. Maternal smoking and drinking behaviour were captured using a parent/guardian questionnaire.

RESULTS

Of the 482 parents/guardians who completed the survey, 29 % reported current drinking 27 % reported past drinking and 10 % reported maternal gestational drinking, while 31 % reported gestational smoking. Significant associations were observed between past and current maternal drinking and child's reduced rapid visual processing accuracy in attention [β:-0.03; 95 % confidence interval (CI): -0.05;-0.004] and between maternal drinking during pregnancy and reduced child's spatial working memory (β: -0.59; CI: -1.02; -0.15). Heavy (>5 cigarettes per day) gestational smoking was associated with lowered child's learning in memory (β:-1.69; 95 % CI: -3.05; -0.33) and lower health-related quality of life (β: -3.41; CI: -6.64; -0.17). The odds of a child repeating a grade were 1.69 (CI: 2.81-1.02) for those exposed to maternal gestational smoking and 1.68 (CI: 3.31-0.85) for those exposed to maternal gestational drinking compared to those who were not exposed.

CONCLUSION

The consistent negative associations across all four maternal substance use proxies, six neurocognitive health outcomes and one health symptom is suggestive of adverse health effects, warranting longitudinal follow-up. Health policies to eliminate gestational substance use are recommended.

Maternal smoking during pregnancy and intelligence quotient in offspring: A systematic review and meta-analysis

BACKGROUND

Exposure to tobacco during pregnancy may disrupt fetal brain development and impact offspring cognitive development.

AIMS

To perform a systematic review and meta-analysis on maternal smoking during pregnancy and intelligence quotient (IQ) in childhood, adolescence, and adulthood.

METHODS

We searched PubMed, Lilacs, PsycINFO, and Web of Science. Original articles evaluating tobacco use/exposure during pregnancy and the offspring's IQ as the outcome. The review protocol is registered in PROSPERO (number CRD 42,019,116,257). For the meta-analysis, we included studies with information on the regression coefficient and its confidence interval (CI) or standard error. Random effects model was used for pooling the estimates.

RESULTS

25 studies were included in the review, and of these 14 met the inclusion criteria for the meta-analysis. The overall pooled estimate showed that subjects who were exposed to maternal smoking during pregnancy presented lower IQ scores, compared to those not exposed to maternal smoking (β -1.30; 95 % CI -1.74, -0.86; I² = 87.8 %); IQ scores were also lower in crude (β -5.46; 95 % CI -7.31, -3.60; I²: 79.0 %) and adjusted pooled estimates (β =-0.45; 95 % CI -0.76, -0.13; I² = 80.4 %), for the group exposed to maternal smoking. In the stratified analysis, an inverse association was also observed in studies with large sample size (n≥1000 participants) (β=-0.49; 95 % CI -0.96, -0.02), among those performed with adolescents (β=-1.16; 95 % CI -2.18, -0.14), and among those adjusted for maternal education (β=-0.57; 95 % CI -1.05, -0.08).

CONCLUSIONS

Our findings suggest that exposure to tobacco during pregnancy may have negative effects on IQ. However, the findings of this meta-analysis should be interpreted with caution.

The association of birth by caesarean section and cognitive outcomes in offspring: a systematic review

PURPOSE

Studies have reported children born by caesarean section are more likely to have lower cognitive outcomes compared to those born by vaginal delivery. This paper reviews the literature examining caesarean birth and offspring cognitive outcomes.

METHODS

A systematic search for observational studies or case-control studies that compared cognitive outcomes of people born by caesarean section with those born by vaginal delivery was conducted in six databases (Medline, PubMed, EMBASE, PsychInfo, CINAHL, Web of Science) from inception until December 2019 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were assessed for quality and a narrative synthesis was undertaken considering the evidence for a causal relationship according to the Bradford Hill Criteria.

RESULTS

A total of seven studies were identified. Of these, four found a significant association between elective and emergency caesarean birth and reduction in offspring cognitive performance as measured by school performance or validated cognitive testing. Three studies found no association. There was variability in the quality of the studies, assessment of the reason for caesarean section (emergency vs elective), measurement of outcomes and adjustment for confounding factors.

CONCLUSION

The evidence of an association between CS birth and lower offspring cognitive functioning is inconsistent. Based on currently available data, there is no evidence that a causal association exists. To better examine this association, future studies should (a) distinguish elective and emergency caesareans, (b) adequately adjust for confounding variables and (c) have valid outcome measures of cognition.

Factors affecting psychosocial development of very low birth weight infants at 18 and 36 months of age

AIM

To identify relationships between neonatal factors including conditions and treatments, nurturing environment, and psychosocial development of children born at very low birth weight (VLBW).

METHODS

In this longitudinal study, the medical records of 113 VLBW infants were examined, and the children were then followed up at 18 and 36 months of age. Their developmental quotient (DQ) was assessed using the Kyoto Scale of Psychological Development (KSPD), and their parents were asked about their own health, financial situation, education, and family support. Pearson's correlation and stepwise multiple regression analyses were used to explore relationships between DQ, potentially significant predictors on the KSPD, and nurturing environment.

RESULTS

DQ at 18 months was associated with the following neonatal factors: mechanical ventilation days (β = -.241, p = .020), Apgar score at 5 min (β = .278, p = .005), periventricular leukomalacia (β = -.218, p = .006), and treatment for retinopathy of prematurity (β = -.171, p = .048) (adjusted R2 = .32). DQ at 36 months was associated with the following neonatal and parenting factors: mechanical ventilation days (β = -.354, p < .001), periventricular leukomalacia (β = -.207, p = .009), sex (β = -.199, p = .011), mother's educational background (β = -.304, p < .001), mother's health status (β = -.159, p = .042) (adjusted R2 = .35).

CONCLUSIONS

These findings suggest that in addition to neonatal clinical parameters including conditions and treatments, the nurturing environment after discharge from the neonatal intensive care unit influences the psychosocial development of VLBW infants.

Identification of Modifiable Social and Behavioral Factors Associated With Childhood Cognitive Performance

IMPORTANCE

Inequities in social environments are likely associated with a large portion of racial disparities in childhood cognitive performance. Identification of the specific exposures associated with cognitive development is needed to inform prevention efforts.

OBJECTIVE

To identify modifiable factors associated with childhood cognitive performance.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal pregnancy cohort study included 1503 mother-child dyads who were enrolled in the University of Tennessee Health Science Center-Conditions Affecting Neurodevelopment and Learning in Early Life study between December 1, 2006, and July 31, 2011, and assessed annually until the children were aged 4 to 6 years. The analytic sample comprised 1055 mother-child dyads. A total of 155 prenatal, perinatal, and postnatal exposures were included to evaluate environment-wide associations. Participants comprised a community-based sample of pregnant women who were recruited between 16 weeks and 28 weeks of gestation from 4 hospitals in Shelby County, Tennessee. Women with high-risk pregnancies were excluded. Data were analyzed from June 1, 2018, to April 15, 2019.

EXPOSURES

Individual and neighborhood socioeconomic position, family structure, maternal mental health, nutrition, delivery complications, birth outcomes, and parenting behaviors.

MAIN OUTCOMES AND MEASURES

Child's full-scale IQ measured by the Stanford-Binet Intelligence Scales, Fifth Edition, at age 4 to 6 years.

RESULTS

Of 1055 children included in the analytic sample, 532 (50.4%) were female. Among mothers, the mean (SD) age was 26.0 (5.6) years; 676 mothers (64.1%) were Black, and 623 mothers (59.0%) had an educational level of high school or less. Twenty-four factors were retained in the least absolute shrinkage and selection operator regression analysis and full models adjusted for potential confounding. Associations were noted between child cognitive performance and parental education and breastfeeding; for each increase of 1.0 SD in exposure, positive associations were found with cognitive growth fostering from observed parent-child interactions (β = 1.12; 95% CI, 0.24-2.00) and maternal reading ability (β = 1.42; 95% CI, 0.16-2.68), and negative associations were found with parenting stress (β = -1.04; 95% CI, -1.86 to -0.21). A moderate increase in these beneficial exposures was associated with a notable improvement in estimated cognitive test scores using marginal means (0.5% of an SD). Black children experienced fewer beneficial cognitive performance exposures; in a model including all 24 exposures and covariates, no racial disparity was observed in cognitive performance (95% CIs for race included the null).

CONCLUSIONS AND RELEVANCE

The prospective analysis identified multiple beneficial and modifiable cognitive performance exposures that were associated with mean differences in cognitive performance by race. The findings from this observational study may help guide experimental studies focused on reducing racial disparities in childhood cognitive performance.

The association between caesarean section and cognitive ability in childhood

PURPOSE

Global rates of caesarean section (CS) rates have increased rapidly in recent years. This is a growing public health concern as it has been proposed that CS may impact cognitive outcomes in childhood. However, the evidence for this association is limited and inconsistent. Therefore, the aim of this study was to investigate the relationship between obstetric mode of delivery and longitudinal cognitive outcomes in childhood.

METHODS

We examined this question using data from a longitudinal cohort study of 8845 participants from the Millennium Cohort Study, a nationally representative UK cohort, who completed a range of verbal and visual-spatial cognitive assessments at ages 3, 5, 7 and 11 years.

RESULTS

We found a statistically significant association between planned CS and visual-spatial cognitive delay in the pattern construction assessment at age 5 (OR 1.31, 95% CI 0.99-1.72) and age 7 (OR 1.42, 95% CI 1.12-1.81). Additionally planned CS was also associated with increased odds of "early childhood delay" (OR 1.70, 95% CI 1.15-2.50) and borderline increased odds of "persistent delay" (OR 1.37, 95% CI 0.99-1.89) in visual-spatial cognitive tests. Mode of delivery was not associated with verbal ability or with patterns of delay at any age point in verbal cognitive tests.

CONCLUSION

We have reported a small association between planned CS and visual-spatial cognitive delay in childhood. However, while this result should be interpreted with caution, it highlights the need to further explore this potential relationship and the causal basis of such an association.

Early life predictors of intelligence in young adulthood and middle age

BACKGROUND

Studies on early predictors of intelligence often focus on single or few predictors and often on childhood intelligence. This study compared the contributions of a broad selection of potential early predictors of intelligence at different adult ages.

METHODS

Information on predictors was recorded prospectively in the Copenhagen Perinatal Cohort during pregnancy, at delivery, and at 1- and 3-year examinations for children born between 1959-61. Adult intelligence was assessed at three independent follow-ups using three different tests of intelligence: Børge Priens Prøve, Wechsler Adult Intelligence Scale, and Intelligenz-Struktur-Test 2000R. From a total of 4697 cohort members, three non-overlapping samples were derived.

RESULTS

The included predictors explained between 22.2-24.3% of the variance in adult IQ, with parental socioeconomic status and sex explaining 16.2-17.0%. Other consistent predictors were head circumference at birth, increase in head circumference head during the first three years, and 3-year milestones. Head circumference was the most important anthropometric measure compared to measures of weight and length.

CONCLUSION

Besides social status and sex, the strongest and most consistent early predictors of adult intelligence were physical or behavioural characteristics that to some extent reflect brain-and cognitive development.

Cognitive function among schoolchildren in Lebanon: association with maternal alcohol drinking and smoking during pregnancy and domestic use of detergents and pesticides during childhood

To evaluate the relation between caregiver exposure to toxics during pregnancy and childhood and the child's cognitive function in Lebanese children. This was a cross-sectional study conducted on Lebanese students in public and private schools from November 2017 to May 2018, enrolling 464 children. A first linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child as independent variables, showed that higher age (Beta = 1.65) was significantly associated with higher cognition, whereas a history of eczema in any of the parents (Beta = -7.32) was significantly associated with lower cognition in the child. A second linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child, and the exposure to toxics as independent variables, showed that maternal alcohol intake during pregnancy (Beta = -1.07) and detergent mixing (Beta = -1.48) were significantly associated with lower cognition in the child. A third linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child, the exposure to toxics and the diseases in the child as independent variables, showed that maternal alcohol intake during pregnancy (Beta = -1.07) and detergent mixing (Beta = -1.45) were significantly associated with lower cognition in the child, whereas a history of eczema in the child before the age of 2 years (Beta = 8.72) was significantly associated with higher cognition in the child. This study is the first to examine the association of a child's prenatal exposure and their exposure during childhood to environmental toxicants with their cognitive function in Lebanon. We consider this study to be important as it shows the possible effect of cleaning products mixing and maternal alcohol consumption on cognitive functions among children in Lebanon.

The microbiota-gut-brain axis: A promising avenue to foster healthy developmental outcomes

Fostering healthy developmental growth in the first years of life is associated with numerous favorable cognitive, social, and economic outcomes. Funding and promoting research aimed at identifying potential targets for early intervention should be a top priority for lawmakers and funders. One promising avenue of research and potential early intervention is the microbiota–gut–brain axis. In this report, we briefly examine the role of the gut microbiota in human life, focusing on links with health, cognition, and behavior. We then discuss the development of the gut microbiota and the critical early window in which colonization occurs. Then, we review current nonnutritive means of influencing the gut microbiota in early life. Finally, we discuss the implications this work has for early intervention in low‐income communities and end with recommendations regarding further research and research funding priorities.

Maternal smoking during pregnancy and academic achievement of offspring over time: A registry data-based cohort study

Few studies have assessed the cumulative impact of maternal smoking during pregnancy (MSDP) on scholastic outcomes over time. We examined the relations between MSDP and academic achievement in the 4th, 7th and 10th grades using registry data collected at birth, during the neonatal period, and at each grade level from the 2000, LIFECOURSE study birth cohort in Reykjavik, Iceland (N = 1151, girls = 49.3%). Latent growth modeling showed that MSDP influenced Icelandic achievement scores, standardized to a range from 0 to 60, at baseline (β = -0.04), and over time (β = -0.05). Likewise, MSDP was negatively associated with standardized mathematics scores at baseline (ß = -0.09) and continued to exert a negative impact on mathematics scores over time (ß = -0.08) after controlling for gender, income, cohabitation, and baseline mathematics and Icelandic achievement scores. Results provide evidence of the persistent negative impact of MSDP on academic achievement in offspring. Findings support the proposition that children whose mothers smoke during the first trimester of pregnancy are, on average, at greater risk for poor scholastic outcomes over time than children whose mothers do not smoke during their first trimester. To our knowledge, this is the first study using a longitudinal cohort design to assess whether the impacts of maternal smoking during pregnancy may persist over time. This study contributes to the current state of knowledge by providing an assessment that focuses on the impact of smoking during pregnancy on academic achievement from childhood into early adolescence.

Childhood social class and cognitive aging in the Swedish Adoption/Twin Study of Aging

In this report we analyzed genetically informative data to investigate within-person change and between-person differences in late-life cognitive abilities as a function of childhood social class. We used data from nine testing occasions spanning 28 y in the Swedish Adoption/Twin Study of Aging and parental social class based on the Swedish socioeconomic index. Cognitive ability included a general factor and the four domains of verbal, fluid, memory, and perceptual speed. Latent growth curve models of the longitudinal data tested whether level and change in cognitive performance differed as a function of childhood social class. Between-within twin-pair analyses were performed on twins reared apart to assess familial confounding. Childhood social class was significantly associated with mean-level cognitive performance at age 65 y, but not with rate of cognitive change. The association decreased in magnitude but remained significant after adjustments for level of education and the degree to which the rearing family was supportive toward education. A between-pair effect of childhood social class was significant in all cognitive domains, whereas within-pair estimates were attenuated, indicating genetic confounding. Thus, childhood social class is important for cognitive performance in adulthood on a population level, but the association is largely attributable to genetic influences.

Associations between the duration of active commuting to school and academic achievement in rural Chilean adolescents

Background

Habitual active commuting to school may be positively associated with academic achievement. The aim of this study was to examine the relationship between duration of walking or otherwise actively commuting to school and academic achievement.

Methods

This cross-sectional study included 389 adolescents from seven rural schools (12–13 years). Mode and duration of active commuting to school (use of active means such as walking or biking to and from school) and screen time were self-reported. Academic achievement was determined by the outcome in basic grades (language and mathematics).

Results

Active commuting to school was not associated with higher scores in any grades after adjustment for potential confounders. No evidence was found of interactions between gender and academic achievement, but there was interaction with duration of walking (<30 min, 30–60 min, and >60 min). Adjusted binary logistic regression analysis suggested that adolescents who spent between 30 and 60 min actively commuting were more likely to obtain high academic achievement (language and mathematics).

Conclusions

Thirty to 60 min of ACS may have a positive influence on academic achievement in adolescents, so, it is necessary to make recommendations for the children to walk from and/or to school. This could help society to recognize the relevance of physical activity to health as well as to academic performance.

Vocabulary development in Norwegian L1 and L2 learners in the kindergarten-school transition

This study examined the vocabulary development of Norwegian second language (L2) learners with Urdu/Punjabi as their first language (L1) at two time-points from kindergarten to primary school, and compared it to the vocabulary development of monolingual Norwegian children. Using path models, the associations between number of picture books in the home, maternal education, and previous L1 and L2 vocabulary on the development of L2 vocabulary breadth and depth were investigated. The results indicate that despite the weaker vocabulary skills of the L2 sample, the growth trajectories of the L2 learners and the monolingual comparison group did not differ. For the L2 learners, we identified both concurrent and longitudinal predictors of vocabulary: the number of books in the home and the time of introduction of the L2 predicted concurrent vocabulary. L1 vocabulary, number of books in the home, and the time of introduction of the L2 predicted vocabulary growth.

Impaired Gas Exchange at Birth and Risk of Intellectual Disability and Autism: A Meta-analysis

We conducted meta-analyses of 67 studies on the association between neonatal proxies of impaired gas exchange and intellectual disability (ID) or autism spectrum disorders (ASD). Neonatal acidosis was associated with an odds ratio (OR) of 3.55 [95 % confidence interval (95 % CI) 2.23-5.49] for ID and an OR of 1.10 (95 % CI 0.91-1.31) for ASD. Children with a 5-min Apgar score of <7 had an OR of 5.39 (95 % CI 3.84-7.55) for ID and an OR of 1.67 (95 % CI 1.34-2.09) for ASD. O2 treatment was associated with an OR of 4.32 (95 % CI 3.23-5.78) for ID and an OR of 2.02 (95 % CI 1.45 to 2.83) for ASD. Our meta-analysis demonstrates an increased risk of ID and (to a lesser extent) ASD in children with neonatal hypoxia. Moreover, our findings raise the possibility that concomitant ID might account for the observed association between the gas exchange proxies and ASD.

Smoking in pregnancy, adolescent mental health and cognitive performance in young adult offspring: results from a matched sample within a Finnish cohort

BACKGROUND

The association between prenatal exposure to maternal cigarette smoking (PEMCS) and adult cognition is debated, including if there are differences according to sex. We aimed to determine if there are associations between PEMCS and cognition in early adulthood in men and women and examine if observed associations were mediated by adolescent mental health factors that are associated with cognition, namely psychotic-like experiences (PLEs), inattention and hyperactivity, and other externalizing behaviors.

METHODS

Participants were 471 individuals drawn from the general population-based Northern Finland 1986 Birth Cohort (NFBC 1986) followed up from pregnancy and birth to early adulthood; individuals with PEMCS were matched with those without PEMCS by socioeconomic and demographic factors. Cognitive performance in adulthood was assessed with a range of tests and their association with PEMCS was measured by sex using hierarchical linear regression, unadjusted and then controlling for potential confounders, mediators and moderators, including adolescent mental health factors.

RESULTS

There were no associations between PEMCS and cognitive scores in females. In males, there were associations with vocabulary (beta = -0.444, 95% CI: -0.783, -0.104) and matrix reasoning (beta = -0.379, 95% CI: -0.711, -0.047).

CONCLUSIONS

While associations between PEMCS and cognition were limited, observed findings with measures of general intelligence in males contribute to suggestions of differences in response to PEMCS by sex. Furthermore, observed associations may be partly mediated by earlier inattention and hyperactivity. Findings add support to efforts aimed to eliminate smoking in pregnancy.

Predicting receptive vocabulary change from childhood to adulthood: A birth cohort study

This study examined the parental and early childhood risk factors of different receptive vocabulary developmental profiles from childhood to adulthood. The sample (n=1914), comprised of monolingual English speaking participants, from the Mater University of Queensland Study of Pregnancy (MUSP). Receptive vocabulary was measured using the Peabody Picture Vocabulary Test-Revised (PPVT-R) at the 5 and 21-year follow ups. Four vocabulary profiles were evident: persistently typical, persistently impaired, later onset of difficulties, and resolved delays. The presence of internalising behaviours at 5 years, lower paternal educational attainment, and maternal smoking during pregnancy were associated with later onset vocabulary impairment. These findings have clinical and educational implications for identifying children 'at risk' of later deterioration in language skills.

Age at menarche and performance intelligence quotients of adolescents in Bangkok, Thailand: a cross-sectional study

Background

The presence of an association between age at the onset of puberty and intelligence quotient (IQ) in young adolescents remains controversial. The aim of this study was to explore the association between age at menarche and performance IQ scores of young female adolescents in Bangkok, Thailand.

Methods

A cross-sectional study was conducted among 537 students aged 11–15 years attending primary and secondary schools in the Dusit district of Bangkok, Thailand. The participants were selected based on two-step stratified sampling. Age at menarche and health and socioeconomic status were determined using a self-report questionnaire completed by participants. Performance IQ scores were determined using the Standard Progressive Matrices intelligence test (Thai version) administered by registered clinical psychologists.

Results

Of the 537 participants, 0.4 had reached menarche at 8 years of age, 1.9 at 9 years, 10.1 at 10 years, 36.1 at 11 years, 37.6 at 12 years, 10.4 at 13 years, 3.4 at 14 years, and 0.2 % at 15 years. Age at menarche was inversely correlated with performance IQ (Pearson correlation −0.087, p = 0.047). The regression equation predicting performance IQ by age at menarche was performance IQ = 128.06 − 1.16*age at menarche (R² = 0.008). In univariate analysis, performance IQ was inversely correlated with age at menarche, body mass index (BMI), time spent watching television, and time sleeping, but was directly correlated with maternal age at birth (all p < 0.05). In multivariate analysis, age at menarche and BMI remained significantly inversely correlated with performance IQ (p < 0.05), while maternal age at birth was directly correlated with performance IQ. The model consisting of age at menarche, BMI, and maternal age at birth best predicted performance IQ.

Conclusion

After adjusting for confounders, multiple regression analysis showed that age at menarche and BMI of young female adolescents living in the Dusit district of Bangkok, Thailand, were inversely correlated with performance IQ, whereas maternal age at birth was directly correlated with performance IQ.

School effects on non-verbal intelligence and nutritional status in rural Zambia

This study uses hierarchical linear modeling (HLM) to examine the school factors (i.e., related to school organization and teacher and student body) associated with non-verbal intelligence (NI) and nutritional status (i.e., body mass index; BMI) of 4204 3^rd to 7^th graders in rural areas of Southern Province, Zambia. Results showed that 23.5% and 7.7% of the NI and BMI variance, respectively, were conditioned by differences between schools. The set of 14 school factors accounted for 58.8% and 75.9% of the between-school differences in NI and BMI, respectively. Grade-specific HLM yielded higher between-school variation of NI (41%) and BMI (14.6%) for students in grade 3 compared to grades 4 to 7. School factors showed a differential pattern of associations with NI and BMI across grades. The distance to a health post and teacher's teaching experience were the strongest predictors of NI (particularly in grades 4, 6 and 7); the presence of a preschool was linked to lower BMI in grades 4 to 6. Implications for improving access and quality of education in rural Zambia are discussed.

Objectively measured sedentary time and academic achievement in schoolchildren

This study aimed to evaluate the relationship between objectively measured total sedentary time and academic achievement (AA) in Portuguese children. The sample comprised of 213 children (51.6% girls) aged 9.46 ± 0.43 years, from the north of Portugal. Sedentary time was measured with accelerometry, and AA was assessed using the Portuguese Language and Mathematics National Exams results. Multilevel linear regression models were fitted to assess regression coefficients predicting AA. The results showed that objectively measured total sedentary time was not associated with AA, after adjusting for potential confounders.

The impact of thyroid abnormalities during pregnancy on subsequent neuropsychological development of the offspring: a meta-analysis

OBJECTIVE

To investigate the relationship between specific thyroid abnormalities in women during pregnancy and the subsequent neuropsychological development of their offspring.

METHODS

A systematic literature search of PubMed, Embase and Web of Science was conducted. Eligible studies were case-control or cohort study that explored this association with euthyroid thyroid abnormalities during pregnancy. The outcomes included intelligence scores and motor scores. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated and heterogeneity was assessed with Cochrane Q chi-square test and I(2) statistics. A fixed-effects or random-effects model was used to pool the estimates according to the heterogeneity among the included studies.

RESULTS

Six studies, involving 4449 participants, were included. Children of women with thyroid abnormalities had mean intelligence score of 6.27 points and motor score of 5.99 points lower than that of children of euthyroid women. Subgroup analysis suggested that, children of women with hypothyroxinaemia, subclinical hypothyroidism and positive TPOAb had mean intelligence scores of 5.69 points, 8.76 points and 10.55 points, and mean motor scores of 4.19 points, 9.98 points and 9.03 points lower than those of the controls, respectively.

CONCLUSIONS

The thyroid abnormalities in pregnant women may adversely affect neuropsychological development of their offspring.

The contribution of visual processing to academic achievement in adolescents born extremely preterm or extremely low birth weight

Children born extremely preterm (EP, <28 weeks) and/or extremely low birth weight (ELBW, <1000 g) have more academic deficiencies than their term-born peers, which may be due to problems with visual processing. The aim of this study is to determine (1) if visual processing is related to poor academic outcomes in EP/ELBW adolescents, and (2) how much of the variance in academic achievement in EP/ELBW adolescents is explained by visual processing ability after controlling for perinatal risk factors and other known contributors to academic performance, particularly attention and working memory. A geographically determined cohort of 228 surviving EP/ELBW adolescents (mean age 17 years) was studied. The relationships between measures of visual processing (visual acuity, binocular stereopsis, eye convergence, and visual perception) and academic achievement were explored within the EP/ELBW group. Analyses were repeated controlling for perinatal and social risk, and measures of attention and working memory. It was found that visual acuity, convergence and visual perception are related to scores for academic achievement on univariable regression analyses. After controlling for potential confounds (perinatal and social risk, working memory and attention), visual acuity, convergence and visual perception remained associated with reading and math computation, but only convergence and visual perception are related to spelling. The additional variance explained by visual processing is up to 6.6% for reading, 2.7% for spelling, and 2.2% for math computation. None of the visual processing variables or visual motor integration are associated with handwriting on multivariable analysis. Working memory is generally a stronger predictor of reading, spelling, and math computation than visual processing. It was concluded that visual processing difficulties are significantly related to academic outcomes in EP/ELBW adolescents; therefore, specific attention should be paid to academic remediation strategies incorporating the management of working memory and visual processing in EP/ELBW children.

Prenatal and neonatal risk factors associated with children's developmental status at ages 4-7: lessons from the Jiangsu China birth defects prevention cohort

BACKGROUND

There is limited information involving population data about the role of maternal health, fetal growth and neonatal health on children's developmental status at ages 4-7 years. Our aim was to determine the contribution of maternal, fetal and neonatal health to developmental status at ages 4-7 years.

METHODS

In this 7-year follow-up prospective cohort study, a sample of 26,803 mothers participated in the beginning. Among their children, 19,187 voluntarily completed the development screening test or the social life ability survey, which were designed for two different age groups (<6 or ≥ 6 years old, respectively). Logistic regression analysis was used to link the data with the prenatal outcome card and interview questionnaire applied to pregnant women in previous study, to the analysis of various related factors such as demographic, socio-economic, disease and menstrual history, marriage and pregnancy care.

RESULT

Univariate and multivariate logistic regression analysis were used separately in two age groups [4-6 (n = 8439) and 6-7 (n = 10,748) years old] to analyse relative factors. Maternal age of 25-30 years, maternal education of high school and greater, family income and not drinking during pregnancy were associated with higher scores in development.

CONCLUSION

Both preconception and pregnancy health education and health care are the important maternal factors closely associated with children's cognitive and social competence. Public health policies for preconception care and public welfare for high-quality childcare are essential for improving children's life.

Older maternal age and child behavioral and cognitive outcomes: a review of the literature

The trend toward delayed childbearing is widespread in industrialized nations. Although the physical consequences for offspring in utero and in the prenatal period are well known, the psychologic consequences of older motherhood for offspring have received less attention in the literature. In contrast to the heightened physical risks for offspring, the existing research suggests that children of older mothers are often at lower risk for problem behavioral and academic outcomes compared with offspring of mothers in their teens and twenties. Maternal age is inextricably linked with a complex web of psychosocial variables, and the challenge for future research is to better understand the relative influence of these variables on the relationship between maternal age and offspring outcomes.

Relation of intelligence quotient and body mass index in preschool children: a community-based cross-sectional study

OBJECTIVE

Overweight and obesity in children is a global problem. Besides physical effects, obesity has harmful psychological effects on children.

METHODS

We carried out cross-sectional community-based study to investigate the relation between body mass index (BMI) and cognitive functioning in preschool children. Thirteen socioeconomical elements of 1151 children were measured and analyzed based on their intelligence quotient (IQ) test results. Thirteen out of 33 provinces were selected randomly, and schools were selected as clusters in rural and urban areas. Descriptive statistics, t-test, analysis of variance and regression were used when appropriate.

RESULTS

Our analysis showed that IQ was associated with household income, place of residence, delivery type, type of infant feeding and father's and mother's education level (P<0.001 for all). Using penalized linear regression for eliminating the impact of confounding factor, our study shows that, living in metropolitan (β=2.411) and urban areas (β=2.761), the level of participants' father's education (β=5.251) was positively and BMI (β=-0.594) was negatively related with IQ test results.ConclusionsThe findings of the present study showed that a lower IQ score is associated with higher BMI. However, this relation appears to be largely mediated when the socioeconomic status was considered.

Social variables predict gains in cognitive scores across the preschool years in children with birth weights 500 to 1250 grams

OBJECTIVE

To determine the extent that social variables influence cognitive development of very low birth weight (VLBW) infants across the preschool years.

STUDY DESIGN

Participants were VLBW (500-1250 g) children enrolled in the Caffeine for Apnea of Prematurity randomized trial between 1999 and 2004. We investigated the relationships between 4 potential social advantages: higher maternal education, higher paternal education, caregiver employment, and 2 biologic parents in the same home--and gain in cognitive scores. Cognitive assessments were performed at the corrected ages of 18 months (Mental Development Index score on the Bayley Scales of Infant Development II) and 5 years (Full Scale IQ on the Wechsler Preschool and Primary Scale of Intelligence III). Cognitive gain was computed by subtracting each individual 18-month Mental Development Index score from the corresponding Full Scale IQ at 5 years.

RESULTS

Data were available for 1347 children. Mean (SD) cognitive scores were 90.8 (15.7) at 18 months and 98.9 (14.5) at 5 years. Multivariable regression showed that higher maternal education, higher paternal education, and caregiver employment had independent and additive effects of similar size on cognitive gain (P < .001); the mean cognitive gain between 18 months and 5 years increased by 3.6 points in the presence of each of these advantages. When all 3 were present, cognitive scores improved on average by 10.9 points compared with children without any of these advantages.

CONCLUSION

In VLBW children, a count of 3 social advantages strongly predicts gains in cognitive scores across the preschool years.

Early life determinants of low IQ at age 6 in children from the 2004 Pelotas Birth Cohort: a predictive approach

Background

Childhood intelligence is an important determinant of health outcomes in adulthood. The first years of life are critical to child development. This study aimed to identify early life (perinatal and during the first year of life) predictors of low cognitive performance at age 6.

Methods

A birth cohort study started in the city of Pelotas, southern Brazil, in 2004 and children were followed from birth to age six. Information on a broad set of biological and social predictors was collected. Cognitive ability—the study outcome—was assessed using the Wechsler Intelligence Scale for Children (WISC). IQ scores were standardized into z-scores and low IQ defined as z < −1. We applied bootstrapping methods for internal validation with a multivariate logistic regression model and carried out external validation using a second study from the 1993 Pelotas Birth Cohort.

Results

The proportion of children with IQ z-score < −1 was 16.9% (95% CI 15.6–18.1). The final model included the following early life variables: child’s gender; parents’ skin color; number of siblings; father’s and mother’s employment status; household income; maternal education; number of persons per room; duration of breastfeeding; height-for-age deficit; head circumference-for-age deficit; parental smoking during pregnancy; and maternal perception of the child’s health status. The area under the ROC curve for our final model was 0.8, with sensitivity of 72% and specificity of 74%. Similar results were found when testing external validation by using data from the 1993 Pelotas Birth Cohort.

Conclusions

The study results suggest that a child’s and her/his family’s social conditions are strong predictors of cognitive ability in childhood. Interventions for promoting a healthy early childhood development are needed targeting children at risk of low IQ so that they can reach their full cognitive potential.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-014-0308-1) contains supplementary material, which is available to authorized users.

Early-life risk factors for chronic nonrespiratory diseases

We have witnessed a change in disease patterns contributing to the global burden of disease, with a shift from early childhood deaths due to the classic infectious communicable diseases to years lived with disability from chronic noncommunicable diseases. In both developing and developed countries, the years lived with disability attributable to chronic disease have increased: cardiovascular diseases by 17.7%; chronic respiratory disease by 8.5%; neurological conditions by 12.2%; diabetes by 30.0%; and mental and behavioural disorders by 5.0% over the past 20 years. Recognition of the contribution made by adverse environmental exposures in early life to noncommunicable diseases in later life is increasing. These early-life exposures appear to contribute to both chronic respiratory and chronic nonrespiratory diseases. In this State of the Art article, we aim to examine early-life environmental exposures that have an epidemiological association with chronic nonrespiratory diseases, such as obesity and type II diabetes, cardiovascular disease, and neurocognitive and behavioural problems. We will highlight the potential overlap in environmental risks with respiratory diseases, and point out knowledge gaps and research opportunities.

Physical growth and nonverbal intelligence: associations in Zambia

OBJECTIVE

To investigate normative developmental body mass index (BMI) trajectories and associations of physical growth indicators--height, weight, head circumference (HC), and BMI--with nonverbal intelligence in an understudied population of children from sub-Saharan Africa.

STUDY DESIGN

A sample of 3981 students (50.8% male), grades 3-7, with a mean age of 12.75 years was recruited from 34 rural Zambian schools. Children with low scores on vision and hearing screenings were excluded. Height, weight, and HC were measured, and nonverbal intelligence was assessed using the Universal Nonverbal Intelligence Test, Symbolic Memory subtest and Kaufman Assessment Battery for Children, Second Edition, Triangles subtest.

RESULTS

Students in higher grades had a higher BMI over and above the effect of age. Girls had a marginally higher BMI, although that for both boys and girls was approximately 1 SD below the international Centers for Disease Control and Prevention and World Health Organization norms. When controlling for the effect of age, nonverbal intelligence showed small but significant positive relationships with HC (r = 0.17) and BMI (r = 0.11). HC and BMI accounted for 1.9% of the variance in nonverbal intelligence, over and above the contribution of grade and sex.

CONCLUSION

BMI-for-age growth curves of Zambian children follow observed worldwide developmental trajectories. The positive relationships between BMI and intelligence underscore the importance of providing adequate nutritional and physical growth opportunities for children worldwide and in sub-Saharan Africa in particular. Directions for future studies are discussed with regard to maximizing the cognitive potential of all rural African children.

Mild prematurity, proximal social processes, and development

OBJECTIVE

To elucidate the role of gestational age in determining the risk of poor developmental outcomes among children born late preterm (34-36 weeks) and early term (37-38 weeks) versus full term (39-41 weeks) by examining the contribution of gestational age to these outcomes in the context of proximal social processes.

METHODS

This was an analysis of the Canadian National Longitudinal Survey of Children and Youth. Developmental outcomes were examined at 2 to 3 (N= 15099) and 4 to 5 years (N= 12302). The sample included singletons, delivered at 34 to 41 weeks, whose respondents were their biological mothers. Multivariable modified Poisson regression was used to directly estimate adjusted relative risks (aRRs). We assessed the role of parenting by using moderation analyses.

RESULTS

In unadjusted analyses, children born late preterm appeared to have greater risk for developmental delay (relative risk = 1.26; 95% confidence interval [CI], 1.01 to 1.56) versus full term. In adjusted analyses, results were nonsignificant at 2 to 3 years (late preterm aRR = 1.13; 95% CI, 0.90 to 1.42; early term aRR = 1.11; 95% CI, 0.96 to 1.27) and 4 to 5 years (late preterm aRR = 1.06; 95% CI, 0.79 to 1.43; early term aRR = 1.03; 95% CI, 0.85 to 1.25). Parenting did not modify the effect of gestational age but was a strong predictor of poor developmental outcomes.

CONCLUSIONS

Our findings show that, closer to full term, social factors (not gestational age) may be the most important influences on development.

Protocol of the PSYCHOTSH study: association between neonatal thyroid stimulating hormone concentration and intellectual, psychomotor and psychosocial development at 4-5 year of age: a retrospective cohort study

Background

Several European countries, including Belgium, still suffer from mild iodine deficiency. Thyroid stimulating hormone (TSH) concentration in whole blood measured at birth has been proposed as an indicator of maternal iodine status during the last trimester of pregnancy. It has been shown that mild iodine deficiency during pregnancy may affect the neurodevelopment of the offspring. In several studies, elevated TSH levels at birth were associated with suboptimal cognitive and psychomotor outcomes among young children. This paper describes the protocol of the PSYCHOTSH study aiming to assess the association between neonatal TSH levels and intellectual, psychomotor and psychosocial development of 4–5 year old children. The results could lead to a reassessment of the recommended cut-off levels of 5 > mU/L used for monitoring iodine status of the population.

Methods

In total, 380 Belgian 4–5 year old preschool children from Brussels and Wallonia with a neonatal blood spot TSH concentration between 0 and 15 mU/L are included in the study. For each sex and TSH-interval (0–1, 1–2, 2–3, 3–4, 4–5, 5–6, 6–7, 7–8, 8–9 and 9–15 mU/L), 19 newborns were randomly selected from all newborns screened by the neonatal screening centre in Brussels in 2008–2009. Infants with congenital hypothyroidism, low birth weight and prematurity were excluded from the study. Neonatal TSH concentration was measured by the Autodelphia method in dried blood spots, collected by heel stick on filter paper 3 to 5 days after birth. Cognitive abilities and psychomotor development are assessed using the Wechsler Preschool and Primary Scale of Intelligence - third edition - and the Charlop-Atwell Scale of Motor coordination. Psychosocial development is measured using the Child Behaviour Check List for age 1½ to 5 years old. In addition, several socioeconomic, parental and child confounding factors are assessed.

Conclusions

This study aims to clarify the effect of mild iodine deficiency during pregnancy on the neurodevelopment of the offspring. Therefore, the results may have important implications for future public health recommendations, policies and practices in food supplementation. In addition, the results may have implications for the use of neonatal TSH screening results for monitoring the population iodine status and may lead to the definition of new TSH cut-offs for determination of the severity of iodine status and for practical use in data reporting by neonatal screening centres.

Maternal pre-pregnancy BMI and intelligence quotient (IQ) in 5-year-old children: a cohort based study

BACKGROUND

An association between maternal pre-pregnancy BMI and childhood intelligence quotient (IQ) has repeatedly been found but it is unknown if this association is causal or due to confounding caused by genetic or social factors.

METHODS

We used a cohort of 1,783 mothers and their 5-year-old children sampled from the Danish National Birth Cohort. The children participated between 2003 and 2008 in a neuropsychological assessment of cognitive ability including IQ tests taken by both the mother and the child. Linear regression analyses were used to estimate the associations between parental BMI and child IQ adjusted for a comprehensive set of potential confounders. Child IQ was assessed with the Wechsler Primary and Preschool Scales of Intelligence--Revised (WPPSI-R).

RESULTS

The crude association between maternal BMI and child IQ showed that BMI was adversely associated with child IQ with a reduction in IQ of -0.40 point for each one unit increase in BMI. This association was attenuated after adjustment for social factors and maternal IQ to a value of -0.27 (-0.50 to -0.03). After mutual adjustment for the father's BMI and all other factors except maternal IQ, the association between paternal BMI and child IQ yielded a regression coefficient of -0.26 (-0.59 to 0.07), which was comparable to that seen for maternal BMI (-0.20 (-0.44 to 0.04)).

CONCLUSION

Although maternal pre-pregnancy BMI was inversely associated with the IQ of her child, the similar association with paternal BMI suggests that it is not a specific pregnancy related adiposity effect.

Contribution of brain size to IQ and educational underperformance in extremely preterm adolescents

Objectives

Extremely preterm (EP) survivors have smaller brains, lower IQ, and worse educational achievement than their term-born peers. The contribution of smaller brain size to the IQ and educational disadvantages of EP is unknown. This study aimed (i) to compare brain volumes from multiple brain tissues and structures between EP-born (<28weeks) and term-born (≥37weeks) control adolescents, (ii) to explore the relationships of brain tissue volumes with IQ and basic educational skills and whether this differed by group, and (iii) to explore how much total brain tissue volume explains the underperformance of EP adolescents compared with controls.

Methods

Longitudinal cohort study of 148 EP and 132 term controls born in Victoria, Australia in 1991-92. At age 18, magnetic resonance imaging-determined brain volumes of multiple tissues and structures were calculated. IQ and educational skills were measured using the Wechsler Abbreviated Scale of Intelligence (WASI) and the Wide Range Achievement Test(WRAT-4), respectively.

Results

Brain volumes were smaller in EP adolescents compared with controls (mean difference [95% confidence interval] of -5.9% [-8.0, -3.7%] for total brain tissue volume). The largest relative differences were noted in the thalamus and hippocampus. The EP group had lower IQs(-11.9 [-15.4, -8.5]), spelling(-8.0 [-11.5, -4.6]), math computation(-10.3 [-13.7, -6.9]) and word reading(-5.6 [-8.8, -2.4]) scores than controls; all p-values<0.001. Volumes of total brain tissue and other brain tissues and structures correlated positively with IQ and educational skills, a relationship that was similar for both the EP and controls. Total brain tissue volume explained between 20-40% of the IQ and educational outcome differences between EP and controls.

Conclusions

EP adolescents had smaller brain volumes, lower IQs and poorer educational performance than controls. Brain volumes of multiple tissues and structures are related to IQ and educational outcomes. Smaller total brain tissue volume is an important contributor to the cognitive and educational underperformance of adolescents born EP.

Breast milk and cognitive development--the role of confounders: a systematic review

OBJECTIVES

The association between breastfeeding and child cognitive development is conflicted by studies reporting positive and null effects. This relationship may be confounded by factors associated with breastfeeding, specifically maternal socioeconomic class and IQ.

DESIGN

Systematic review of the literature.

SETTING AND PARTICIPANTS

Any prospective or retrospective study, in any language, evaluating the association between breastfeeding and cognitive development using a validated method in healthy term infants, children or adults, was included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Extracted data included the study design, target population and sample size, breastfeeding exposure, cognitive development assessment tool used and participants' age, summary of the results prior to, and following, adjustment for confounders, and all confounders adjusted for. Study quality was assessed as well.

RESULTS

84 studies met our inclusion criteria (34 rated as high quality, 26 moderate and 24 low quality). Critical assessment of accepted studies revealed the following associations: 21 null, 28 positive, 18 null after adjusting for confounders and 17 positive-diminished after adjusting for confounders. Directionality of effect did not correlate with study quality; however, studies showing a decreased effect after multivariate analysis were of superior quality compared with other study groupings (14/17 high quality, 82%). Further, studies that showed null or diminished effect after multivariate analysis corrected for significantly more confounders (7.7±3.4) as compared with those that found no change following adjustment (5.6±4.5, p=0.04). The majority of included studies were carried out during childhood (75%) and set in high-income countries (85.5%).

CONCLUSIONS

Much of the reported effect of breastfeeding on child neurodevelopment is due to confounding. It is unlikely that additional work will change the current synthesis. Future studies should attempt to rigorously control for all important confounders. Alternatively, study designs using sibling cohorts discordant for breastfeeding may yield more robust conclusions.