Meta-analysis of epigenome-wide associations between DNA methylation at birth and childhood cognitive skills.

Cognitive skills are a strong predictor of a wide range of later life outcomes. Genetic and epigenetic associations across the genome explain some of the variation in general cognitive abilities in the general population and it is plausible that epigenetic associations might arise from prenatal environmental exposures and/or genetic variation early in life. We investigated the association between cord blood DNA methylation at birth and cognitive skills assessed in children from eight pregnancy cohorts within the Pregnancy And Childhood Epigenetics (PACE) Consortium across overall (total N = 2196), verbal (total N = 2206) and non-verbal cognitive scores (total N = 3300). The associations at single CpG sites were weak for all of the cognitive domains investigated. One region near DUSP22 on chromosome 6 was associated with non-verbal cognition in a model adjusted for maternal IQ. We conclude that there is little evidence to support the idea that variation in cord blood DNA methylation at single CpG sites is associated with cognitive skills and further studies are needed to confirm the association at DUSP22.

Head circumference and child ADHD symptoms and cognitive functioning: results from a large population-based cohort study.

The aim of this study is to understand the association between prenatal, newborn and postnatal head circumference (HC) and preschool neurodevelopment in a large population-based birth cohort. The INMA project followed 1795 children from 12 weeks of pregnancy to preschool years. HC measurements were carried out prospectively, and following a standardized protocol during pregnancy (12, 20 and 34 weeks), birth, and child ages of 1-1.5 and 4 years old; and z-scores were further estimated. Prenatal head growth was assessed using conditional z-scores between weeks 12-20 and 20-34. Several neuropsychological tests [MSCA (cognition), CPT (attention)] and behavioral rating scales [DSM-IV-ADHD, CAST (autism), CPSCS (social competence)] were carried out during the last follow-up (5 years old). Multivariable models adjusted for family and child characteristics were applied to analyze associations between HC and neurodevelopment. In fully adjusted models, prenatal HC and head growth showed little or no associations with the neurodevelopment outcomes. Independent associations were observed between HC z-scores at birth, 1-1.5 years and 4 years and MSCA global cognitive scores and DSM-IV inattention symptoms. Specifically, z-score at birth was positively associated with general cognitive scores [ß 1.22, 95% confidence interval (CI) 0.59, 1.85], and we observed a protective association with ADHD-DSM-IV total symptoms, mean ratio (MR) 0.85 (0.75, 0.96). Prenatal HC and head growth measurements gave little information about child cognitive abilities and behavior at preschool years. However, HC at birth and early childhood was positively associated with a range of neuropsychological outcomes, including protective associations with ADHD symptoms.

Prenatal exposure to cell phone use and neurodevelopment at 14 months.

BACKGROUND: Recently, an association was reported between prenatal and postnatal exposure to cell phones and neurobehavioral problems in children at the age of 7 years. METHODS: A birth cohort was established in Sabadell, Spain between 2004 and 2006. Mothers completed questions about cell phone use in week 32 of the pregnancy (n = 587). Neurodevelopment of their children was tested at age 14 months using the Bayley Scales of Infant Development (n = 530). RESULTS: We observed only small differences in neurodevelopment scores between the offspring of cell phone users and nonusers. Those of users had higher mental development scores and lower psychomotor development scores, which may be due to unmeasured confounding. There was no trend with amount of cell phone use within users. CONCLUSION: This study gives little evidence for an adverse effect of maternal cell phone use during pregnancy on the early neurodevelopment of offspring.

Association between child cortisol levels in saliva and neuropsychological development during the second year of life.

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.

Maternal intelligence-mental health and child neuropsychological development at age 14 months.

OBJECTIVE: To examine the relationship between maternal intelligence-mental health and neuropsychological development at age 14 months in a normal population, taking into account maternal occupational social class and education. METHODS: We prospectively studied a population-based birth cohort, which forms part of the INMA (Environment and Childhood) Project. Cognitive and psychomotor development was assessed at 14 months using Bayley Scales of Infant Development. Maternal intelligence and mental health were assessed by the Cattell and Cattell test and the General Health Questionnaire-12 respectively. RESULTS: We observed a crude association between maternal intelligence and cognitive development in children at 14 months but this association disappeared when maternal education was included. The associations were stratified by maternal education and occupational social class. Within the manual maternal occupational social class, there was a significant difference in cognitive development between children whose mothers scored in the highest tertile of maternal IQ and those whose mothers scored in the lowest tertile. In contrast, no differences were observed among children whose mothers were in the non-manual occupational social class. CONCLUSIONS: The association between maternal intelligence and child cognitive development differed by occupational social class. While this association was not confounded by education or other variables in manual occupational social classes, maternal education explained this association among advantaged occupational social classes.

Breastfeeding, long-chain polyunsaturated fatty acids in colostrum, and infant mental development.

BACKGROUND: Breastfeeding has been associated with improved neurodevelopment in children. However, it remains unknown to what extent nutritional advantages of breast milk may explain this relationship. OBJECTIVE: We assessed the role of parental psychosocial factors and colostrum long-chain polyunsaturated fatty acid (LC-PUFA) levels in the relationship between breastfeeding and children's neurodevelopment. METHODS: A population-based birth cohort was established in the city of Sabadell (Catalonia, Spain) as part of the INMA-INfancia y Medio Ambiente Project. A total of 657 women were recruited during the first trimester of pregnancy. Information about parental characteristics and breastfeeding was obtained by using a questionnaire, and trained psychologists assessed mental and psychomotor development by using the Bayley Scales of Infant Development in 504 children at 14 months of age. RESULTS: A high percentage of breastfeeds among all milk feeds accumulated during the first 14 months was positively related with child mental development (0.37 points per month of full breastfeeding [95% confidence interval: 0.06-0.67]). Maternal education, social class, and intelligence quotient only partly explained this association. Children with a longer duration of breastfeeding also exposed to higher ratios between n-3 and n-6 PUFAs in colostrum had significantly higher mental scores than children with low breastfeeding duration exposed to low levels. CONCLUSIONS: Greater levels of accumulated breastfeeding during the first year of life were related to higher mental development at 14 months, largely independently from a wide range of parental psychosocial factors. LC-PUFA levels seem to play a beneficial role in children's mental development when breastfeeding levels are high.