Prenatal cigarette exposure and infant learning stimulation as predictors of cognitive control in childhood

The effect of maternal prenatal tobacco smoking on offspring academic achievement: A systematic review and meta-analysis

BACKGROUND

Previous epidemiological studies examining the prospective association between maternal prenatal tobacco smoking and offspring academic achievement have reported conflicting results. Therefore, this systematic review and meta-analysis was conducted to examine the magnitude and consistency of association reported by those studies.

METHODS

This systematic review and meta-analysis was guided by the PRISMA protocol. Relevant epidemiological studies on the topic were extracted from four main databases (PubMed/Medline, Embase, PsycINFO, and Scopus). The Newcastle-Ottawa Scale (NOS) was used to appraise the methodological quality of the included studies. We conducted a narrative assessment of the studies that did not report effect estimates. Inverse variance-weighted random effect meta-analysis was used to combine studies reporting effect sizes to estimate pooled adjusted odds ratio with 95% confidence intervals (95% CI). The review was prospectively registered in PROSPERO (CRD42022350901).

RESULTS

Nineteen observational studies, published between 1973 and 2021 with a total of 1.25 million study participants were included in the final review. Of these, fifteen studies (79 %) reported reduced academic achievement in offspring exposed to maternal prenatal tobacco smoking. The eight primary studies (sample size = 723,877) included in the meta-analysis together suggested a 49 % higher risk of reduced academic achievement in offspring exposed to maternal prenatal tobacco smoking when compared to non-exposed offspring (Pooled odds ratio = 1.49, 95 % CI:1.17-1.91).

CONCLUSION

Our review found a positive association between maternal prenatal tobacco smoking and offspring reduced academic achievement. However, variation in the adjustment of potential confounders and significant heterogeneity across included studies limited more conclusive inference. Mechanistic studies to identify causal pathways and specific academic impacts are needed to inform targeted developmental programs to assist child learning and academic performance.

Early Risk of Tobacco Smoke Exposure and Preschoolers' Hot and Cool Inhibitory Control: Promotive and Protective Roles of Maternal Positivity in Early Mother-child Interaction

Early tobacco smoke exposure (TSE) in utero and/or during the first years after birth poses threats to the development of child executive functioning and self-regulation skills, including inhibitory control. Efforts are still needed to examine under what conditions such effects may occur and thus identify modifiable intervention targets. In addition, a distinction between cool and hot inhibitory control is also important to obtain greater nuance in such links. The cool inhibitory control refers to children's suppression of prepotent automatic responses to a distracting stimulus in solving arbitrary and decontextualized problems, whereas the hot inhibitory control refers to children's control of impulse in motivationally and emotionally high-stake situations. Using data derived from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, we examined the links between early risk of TSE and preschoolers' hot and cool inhibitory control and tested the potential promotive/protective roles of maternal positivity in early mother-child interactions. Results indicate that early risk of TSE was negatively linked to child cool inhibitory control when maternal positivity was low, but this link was nonsignificant when maternal positivity was high (i.e., the protective role of maternal positivity). The link between early risk of TSE and child later hot inhibitory control was not moderated by maternal positivity; instead, early risk of TSE and maternal positivity were negatively and positively associated with child hot inhibitory control above and beyond each other, respectively (i.e., the promotive role of maternal positivity). Accordingly, building a tobacco-free environment during pregnancy and infancy likely yields long-term benefits for child self-regulation development. Improving early mothering may offset the negative link between early TSE and child cool inhibitory control and also facilitate child hot inhibitory control even in the face of early TSE.

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.

Maternal smoking during pregnancy and poor academic performance in adolescent offspring: A registry data-based cohort study

BACKGROUND

Previous studies have suggested associations between maternal smoking during pregnancy (MSDP) and a range of adverse outcomes in offspring. However, evidence reporting adverse effects on poor academic performance in adolescence is scant.

METHODS

This register-based cohort study used linked data obtained from New South Wales (NSW) educational and health registries in Australia. MSDP was assessed using self-reports of smoking during pregnancy. Offspring's educational performance was assessed using the National Assessment Program for Literacy and numeracy (NAPLAN), when students were in grade 9 and approximately aged 14 years. We used multivariable logistic regression models to explore associations.

RESULTS

Adolescent offspring exposed to MSDP were at an increased risk of substandard academic performance in all domains, with the highest odds for spelling [OR, 3.12 (95%CI 2.98-3.26)] followed by writing [OR, 2.97 (95%CI 2.84-3.11)], reading [OR, 2.49 (95%CI 2.37-2.62)], and numeracy [OR, 2.43 (95%CI 2.30-2.58)]. In our sex-stratified analysis, MSDP displayed stronger effects on the academic performance of female offspring in all domains.

CONCLUSIONS

Our findings showed that MSDP was associated with an increased risk of reduced academic performance in adolescent offspring. The different effects of MSDP on the academic performance of male and female offspring is a new finding, which needs further investigation.

Does early maternal responsiveness buffer prenatal tobacco exposure effects on young children's behavioral disinhibition?

Children with prenatal tobacco exposure (PTE) exhibit early self-regulatory impairments, reflecting a life-course persistent propensity toward behavioral disinhibition. Previously, we demonstrated the protective role of parental responsiveness for reducing the risk of exposure-related disruptive behavior in adolescence. Here, we expanded this line of inquiry, examining whether responsiveness moderates the relation of PTE to a broader set of behavioral disinhibition features in early childhood and testing alternative diathesis-stress versus differential susceptibility explanatory models. PTE was assessed prospectively using interviews and bioassays in the Midwestern Infant Development Study (MIDS). Mother-child dyads (N = 276) were re-assessed at approximately 5 years of age in a preschool follow-up. We quantified maternal responsiveness and child behavioral disinhibition using a combination of directly observed activities in the lab and developmentally sensitive questionnaires. Results supported a diathesis-stress pattern. Children with PTE and less responsive mothers showed increased disruptive behavior and lower effortful control compared with children without PTE. In contrast, exposed children with more responsive mothers had self-regulatory profiles similar to their non-exposed peers. We did not observe sex differences. Findings provide greater specification of the protective role of maternal responsiveness for self-regulation in children with PTE and help clarify mechanisms that may underscore trajectories of exposure-related behavioral disinhibition.

Early Secure Attachment as a Protective Factor Against Later Cognitive Decline and Dementia

The etiology of neurodegenerative disorders such as dementia is complex and incompletely understood. Interest in a developmental perspective to these pathologies is gaining momentum. An early supportive social environment seems to have important implications for social, affective and cognitive abilities across the lifespan. Attachment theory may help to explain the link between these early experiences and later outcomes. This theory considers early interactions between an infant and its caregiver to be crucial to shaping social behavior and emotion regulation strategies throughout adult life. Furthermore, research has demonstrated that such early attachment experiences can, potentially through epigenetic mechanisms, have profound neurobiological and cognitive consequences. Here we discuss how early attachment might influence the development of affective, cognitive, and neurobiological resources that could protect against cognitive decline and dementia. We argue that social relations, both early and late in life, are vital to ensuring cognitive and neurobiological health. The concepts of brain and cognitive reserve are crucial to understanding how environmental factors may impact cognitive decline. We examine the role that attachment might play in fostering brain and cognitive reserve in old age. Finally, we put forward the concept of affective reserve, to more directly frame the socio-affective consequences of early attachment as protectors against cognitive decline. We thereby aim to highlight that, in the study of aging, cognitive decline and dementia, it is crucial to consider the role of affective and social factors such as attachment.

Parenting and toddler self-regulation in low-income families: What does sleep have to do with it?

Toddlerhood is a sensitive period in the development of self-regulation, a set of adaptive skills that are fundamental to mental health and partly shaped by parenting. Healthy sleep is known to be critical for self-regulation; yet, the degree to which child sleep alters interactive child-parent processes remains understudied. This study examines associations between observed parenting and toddler self-regulation, with toddler sleep as a moderator of this association. Toddlers in low-income families (N = 171) and their mothers were videotaped during free play and a self-regulation challenge task; videos were coded for mothers' behavior and affect (free play) and toddlers' self-regulation (challenge task). Mothers reported their child's nighttime sleep duration via questionnaire. Results revealed significant Sleep × Maternal Negative Affect and Sleep × Maternal Negative Control interactions. Children who did not experience negative parenting had good self-regulation regardless of their nighttime sleep duration. For children who did experience negative parenting, self-regulation was intact among those who obtained more nighttime sleep, but significantly poorer among children who were getting less nighttime sleep. Thus, among children who were reported to obtain less nighttime sleep, there were more robust associations between negative parenting and poorer self-regulation than among toddlers who were reported to obtain more sleep.

The quality of air outside and inside the home: associations with emotional and behavioural problem scores in early childhood

Background

This study explored the role of outdoor air pollution [nitrogen dioxide (NO₂) and sulphur dioxide (SO₂)] and indoor air quality (measured with damp or condensation and secondhand smoke exposures) at age 9 months in emotional, conduct and hyperactivity problems at age 3 years.

Method

Data from 11,625 Millennium Cohort Study children living in England and Wales were modelled using multilevel regression.

Results

After adjusting for a host of confounders, having a damp or condensation problem at home was related to both emotional and conduct problems. Secondhand smoke exposure was associated with all three problem types. Associations with outdoor air pollution were less consistent.

Conclusions

Exposures to damp or condensation and secondhand smoke in the home are likely to be risk factors for child emotional and behavioural problems. Parents should continue to be educated about the dangers of exposing their children to poor air quality at home.

A Combined Dietary and Cognitive Intervention in 3⁻5-Year-Old Children in Indonesia: A Randomized Controlled Trial

Early childhood nutritional interventions typically combine nutritional and psychosocial stimulation. Such combined interventions result in long-lasting improvements of cognitive abilities in children who are malnourished. Here, we investigated potential cognitive abilities in normally developing children in Indonesia who were, however, at risk for suboptimal cognitive development due to little psychosocial stimulation in their home environment. In a randomized controlled intervention, children of the experimental group received nutritional supplementation combined with cognitive stimulation. Pre- and post-intervention measurements included cognitive development and functioning, behavior, and mother–child interaction. The experimental and control group received nutritional supplementation in the form of a fortified or unfortified milk powder, respectively. Additionally, the children and parents of the experimental group jointly engaged in daily learning activities at home and performed iPad-based tasks designed to foster cognitive abilities. The experimental group compared to the control group displayed a significantly higher increase in intelligence quotient as well as a significantly larger reduction in attentional problems after the intervention. These results indicate that low-level cognitive stimulation in combination with nutritional supplementation during early childhood can be an effective intervention that improves global cognitive functioning in healthy developing children. ClinicalTrials.gov Identifier: NCT02359669.

Maternal smoking during pregnancy and offspring executive function: What do we know and what are the next steps?

Children exposed to maternal smoking during pregnancy (MSDP) exhibit difficulties in executive function (EF) from infancy through adolescence. Due to the developmental significance of EF as a predictor of adaptive functioning throughout the life span, the MSDP-EF relation has clear public health implications. In this paper, we provide a comprehensive review of the literature on the relationship between MSDP and offspring EF across development; consider brain-based assessments, animal models, and genetically informed studies in an effort to elucidate plausible pathways of effects; discuss implications for prevention and intervention; and make calls to action for future research.

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.

Maternal smoking during pregnancy and scholastic achievement in childhood: evidence from the LIFECOURSE cohort study

Background

Research on the impact of maternal smoking during pregnancy (MSDP) on scholastic achievement in the offspring has shown conflicting findings. The objective of this study was to assess the impact of MSDP on scholastic achievement in a birth cohort of children in 4th, 7th and 10th grades.

Methods

We analysed data from the LIFECOURSE study, a cohort study of risk and protective factors in all children born in Reykjavik, Iceland, in the year 2000 (N = 1151, girls = 49.3%). Retrospective registry data for 2014–2015 were merged with prospective survey data that were collected in April 2016. Data on MSDP were assessed during regular antenatal visits at the end of the first trimester. Standardized academic achievement scores were obtained from official school transcripts. Data were analysed using OLS regressions that were entered in three hierarchical blocks.

Results

Children of mothers who smoked tobacco during the first trimester consistently revealed between 5% and 7% lower scores on standardized academic achievement in 4th, 7th and 10th grade (∼6–8 points on a normally distributed 120 point scale) than those of mothers who had not smoked tobacco during this period (P < 0.05). These findings held after controlling for several factors associated with the time of birth (e.g. birth weight, maternal age at birth, birth order, parental cohabitation and household income), as well as the year of scholastic assessment (parental cohabitation, household income and parental education).

Conclusions

Maternal smoking during pregnancy was negatively related to scholastic achievement in the offspring during 4th, 7th and 10th grade.

Protective Role of Parenting Attitude on the Behavioral and Neurocognitive Development of the Children from Economically Disadvantaged Families

OBJECTIVE

Association between home environment and the behavioral and neurocognitive development of children from a community childcare center for low-income families was examined (aged 6 to 12 years, n=155).

METHODS

The parents performed a questionnaire on home environment (K-HOME-Q) to assess home environment including parenting attitude and the Child Behavior Checklist (K-CBCL). The children performed the Wechsler Intelligence (IQ) Scale, Stroop interference test (Stroop), word fluency test (WF), and design fluency test (DF) to assess their neurocognitive development.

RESULTS

'Nurturing of Development' and 'Variety of Language Interaction' scores from the K-HOME-Q, were inversely associated with total behavior problems, externalization, rule-breaking, and aggressive behavior subscales of K-CBCL, and 'Emotional atmosphere' and 'Tolerance toward the child' scores showed inverse associations with the total behavior problems, rule-breaking, aggressive behavior, and withdrawn/depressed subscales. Despite economic hardship, the mean scores of the neurocognitive tests were comparable to the average level of Korean children's normative sample. However, 'Nurturing of Development' and 'Tolerance toward the Child' score of K-HOME-Q were associated with better executive function (IQ, WF, DF).

CONCLUSION

These results suggest that parental stimulation of development and tolerant parenting attitude may offer protection against the negative effects of suboptimal economic environment on children's behavior and neurocognitive development.

Prevalence and Perceptions of Electronic Cigarette Use during Pregnancy

Objectives The current study is the first to assess pregnant women's perceptions of e-cigarettes and the prevalence of e-cigarette use during pregnancy, using a national sample of pregnant women (N = 445) recruited online. Methods An online survey was used to assess the prevalence and perceptions of e-cigarette use among pregnant women, including perceptions of e-cigarette safety. Results In our sample, 5.62% (n = 25) of women solely used tobacco cigarettes, 6.52% (n = 29) solely used e-cigarettes, 8.54% (n = 38) used both tobacco cigarettes and e-cigarettes, and 79.33% (n = 353) used neither tobacco cigarettes nor e-cigarettes during their current pregnancy. Overall, 64.27% (n = 286) of participants viewed e-cigarettes as being safer than tobacco cigarettes. Having seen advertisements for e-cigarettes increased likelihood of viewing them as safer than tobacco cigarettes (OR [Odds Ratio] = 2.5, p < .01). Conclusions for Practice Taken together, findings from this study suggest that at least as many women use e-cigarettes during pregnancy as tobacco cigarettes, that pregnant women view e-cigarettes as being safer than tobacco cigarettes, and that these views may be influenced by exposure to e-cigarette advertisements.

A meta-analysis of the relationship between socioeconomic status and executive function performance among children

The relationship between childhood socioeconomic status (SES) and executive function (EF) has recently attracted attention within psychology, following reports of substantial SES disparities in children's EF. Adding to the importance of this relationship, EF has been proposed as a mediator of socioeconomic disparities in lifelong achievement and health. However, evidence about the relationship between childhood SES and EF is mixed, and there has been no systematic attempt to evaluate this relationship across studies. This meta-analysis systematically reviewed the literature for studies in which samples of children varying in SES were evaluated on EF, including studies with and without primary hypotheses about SES. The analysis included 8760 children between the ages of 2 and 18 gathered from 25 independent samples. Analyses showed a small but statistically significant correlation between SES and EF across all studies (rrandom  = .16, 95% CI [.12, .21]) without correcting for attenuation owing to range restriction or measurement unreliability. Substantial heterogeneity was observed among studies, and a number of factors, including the amount of SES variability in the sample and the number of EF measures used, emerged as moderators. Using only the 15 studies with meaningful SES variability in the sample, the average correlation between SES and EF was small-to-medium in size (rrandom  = .22, 95% CI [.17, .27]). Using only the six studies with multiple measures of EF, the relationship was medium in size (rrandom  = .28, 95% CI [.18, .37]). In sum, this meta-analysis supports the presence of SES disparities in EF and suggests that they are between small and medium in size, depending on the methods used to measure them.

Outdoor and indoor air quality and cognitive ability in young children

BACKGROUND

This study examined outdoor and indoor air quality at ages 9 months and 3 years and their association with cognitive ability at age 3 in England and Wales.

METHOD

Data from 8198 Millennium Cohort Study children were analysed using multilevel regression. Outdoor air quality was assessed with mean annual estimates of nitrogen dioxide (NO₂) levels within a standard small area (ward). Indoor air quality was measured with parent-reports of damp or condensation in the home and exposure to secondhand smoke in the home. Cognitive ability was assessed with the British Ability Scales Naming Vocabulary subscale and the Bracken School Readiness Assessment.

RESULTS

In adjusted models, consistent exposure to high levels of NO₂ at age 9 months and age 3 years was associated with lower verbal ability at age 3 years. Damp/condensation and secondhand smoke in the home at either age or at both ages were correlated with lower school readiness at age 3 years. Exposures to damp/condensation at age 3 years or at both ages and secondhand smoke at either age or at both ages were associated with lower verbal ability at age 3 years.

CONCLUSION

Young children's exposures to indoor damp or condensation and secondhand smoke are likely to be detrimental for their cognitive outcomes. However, there do not appear to be any short-term effects of NO₂.

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.

Parental smoking during pregnancy shortens offspring's legs

One of the most severe detrimental environmental factors acting during pregnancy is foetal smoke exposure. The aim of this study was to assess the effect of maternal, paternal and parental smoking during pregnancy on relative leg length in 7- to 10-year-old children. The research conducted in the years 2001-2002 included 978 term-born children, 348 boys and 630 girls, at the age of 7-10 years. Information concerning the birth weight of a child was obtained from the health records of the women. Information about the mother's and the father's smoking habits during pregnancy and about the mothers' education level was obtained from a questionnaire. The influence of parental smoking on relative leg length, controlled for age, sex, birth weight and the mother's education, as a proxy measure of socioeconomic status, and controlled for an interaction between sex and birth weight, was assessed by an analysis of covariance, where relative leg length was the dependent variable, smoking and sex were the independent variables, and birth weight as well as the mother's education were the covariates. Three separate analyses were run for the three models of smoking habits during pregnancy: the mother's smoking, the father's smoking and both parents' smoking. Only both parents' smoking showed a significant effect on relative leg length of offspring. It is probable that foetal hypoxia caused by carbon monoxide contained in smoke decelerated the growth of the long bones of foetuses.

Prenatal tobacco exposure and self-regulation in early childhood: Implications for developmental psychopathology

Prenatal tobacco exposure (PTE) has a well-documented association with disruptive behavior in childhood, but the neurocognitive effects of exposure that underlie this link are not sufficiently understood. The present study was designed to address this gap, through longitudinal follow-up in early childhood of a prospectively enrolled cohort with well-characterized prenatal exposure. Three-year-old children (n = 151) were assessed using a developmentally sensitive battery capturing both cognitive and motivational aspects of self-regulation. PTE was related to motivational self-regulation, where children had to delay approach to attractive rewards, but not cognitive self-regulation, where children had to hold information in mind and inhibit prepotent motor responses. Furthermore, PTE predicted motivational self-regulation more strongly in boys than in girls, and when propensity scores were covaried to control for confounding risk factors, the effect of PTE on motivational self-regulation was significant only in boys. These findings suggest that PTE's impact on neurodevelopment may be greater in boys than in girls, perhaps reflecting vulnerability in neural circuits that subserve reward sensitivity and emotion regulation, and may also help to explain why PTE is more consistently related to disruptive behavior disorders than attention problems.

Developmental pathways from prenatal tobacco and stress exposure to behavioral disinhibition

Prenatal tobacco exposure (PTE) and prenatal stress exposure (PSE) both have been linked to externalizing behavior, although their effects generally have been considered in isolation. Here, we aimed to characterize the joint or interactive roles of PTE and PSE in early developmental pathways to behavioral disinhibition, a profile of cognitive and behavioral under-control that presages severe externalizing behavior. As part of a prospective, longitudinal study, 296 children were assessed at a mean age of 5 years. Exposures were assessed via repeated interviews across the prenatal period and bioassays of cotinine were obtained. Behavioral disinhibition was assessed using temperament measures in infancy, performance-based executive control tasks and measures of disruptive and inattentive behavior. PSE was associated with a higher probability of difficult temperament in infancy. Each exposure independently predicted poorer executive control at age 5 years. Difficult temperament and executive control difficulties in turn predicted elevated levels of disruptive behavior, although links from PTE and PSE to parent-reported attention problems were less robust. Children who experienced these prenatal exposures in conjunction with higher postnatal stress exposure showed the lowest executive control and highest levels of disruptive behavior. Findings highlight the compounding adverse impact of PTE and PSE on children's behavioral trajectories. Given their high concordance, prenatal health campaigns should target these exposures in tandem.

Determining the impact of prenatal tobacco exposure on self-regulation at 6 months

Our goal in the present study was to examine the effects of maternal smoking during pregnancy on infant self-regulation, exploring birth weight as a mediator and sex as a moderator of risk. A prospective sample of 218 infants was assessed at 6 months of age. Infants completed a battery of tasks assessing working memory/inhibition, attention, and emotional reactivity and regulation. Propensity scores were used to statistically control for confounding risk factors associated with maternal smoking during pregnancy. After prenatal and postnatal confounds were controlled, prenatal tobacco exposure was related to reactivity to frustration and control of attention during stimulus encoding. Birth weight did not mediate the effect of prenatal exposure but was independently related to reactivity and working memory/inhibition. The effect of tobacco exposure was not moderated by sex.

Is exposure to secondhand smoke associated with cognitive parameters of children and adolescents?--a systematic literature review

PURPOSE

Despite the known association of second hand smoke (SHS) with increased risk of ill health and mortality, the effects of SHS exposure on cognitive functioning in children and adolescents are unclear. Through a critical review of the literature we sought to determine whether a relationship exists between these variables.

METHODS

The authors systematically reviewed articles (dated 1989-2012) that investigated the association between SHS exposure (including in utero due to SHS exposure by pregnant women) and performance on neurocognitive and academic tests. Eligible studies were identified from searches of Web of Knowledge, MEDLINE, Science Direct, Google Scholar, CINAHL, EMBASE, Zetoc, and Clinicaltrials.gov.

RESULTS

Fifteen articles were identified, of which 12 showed inverse relationships between SHS and cognitive parameters. Prenatal SHS exposure was inversely associated with neurodevelopmental outcomes in young children, whereas postnatal SHS exposure was associated with poor academic achievement and neurocognitive performance in older children and adolescents. Furthermore, SHS exposure was associated with an increased risk of neurodevelopmental delay.

CONCLUSIONS

Recommendations should be made to the public to avoid sources of SHS and future research should investigate interactions between SHS exposure and other risk factors for delayed neurodevelopment and poor cognitive performance.

Effects of maternal cigarette smoking during pregnancy on cognitive parameters of children and young adults: a literature review

The long term effects of maternal smoking during pregnancy on the cognitive development of the child are not well understood due to conflicting findings in past research. The aim of this paper was to provide an up to date, critical review of the literature to determine whether there is evidence of a relationship between tobacco smoke exposure in utero and cognitive functioning. We systematically reviewed observational studies (dated 2000-2011) that examined associations between tobacco smoke exposure in utero due to maternal smoking and performance on cognitive, intelligence, neurodevelopmental and academic tests. Eligible studies were identified through searches of Web of Knowledge, Medline, Science Direct, Google Scholar, CINAHL, EMBASE, Zetoc and Clinicaltrials.gov databases. The review found evidence of a relationship between tobacco smoke exposure in utero and reduced academic achievement and cognitive abilities independent of other variables. Maternal smoking during pregnancy may therefore be a modifiable risk factor for reduced cognitive abilities later in the life of the child. Giving up smoking during pregnancy should be initiated as early as possible to reduce the impact on the child's cognitive development.

An exploration of the associations of pregnancy and perinatal features with cytokines and tryptophan/kynurenine metabolism in children with attention-deficit hyperactivity disorder (ADHD)

Intra-individual variability of the characteristics of children with attention-deficit hyperactivity (ADHD) may reflect compromised glial energy supply in the synapse. We reported recently that while serum levels of a glial marker, the cytokine S100B, were not seriously altered, levels of other cytokines and tryptophan metabolites were related to symptoms, attention and variability. Here, we explore with a regression analysis whether levels of these substances were associated with features of the index pregnancy of potential aetiological significance. Serum was taken from 35 children with DSM-IV ADHD (14 on medication) and 21 typically developing controls to measure 8 cytokines (S100B, IL-2, IL-6, IL-10, IL-13, IL-16, TNF-α and IFN-γ) and 5 metabolites (Tryptophan, Kynurenine, Kynurenate [KA], 3-hydroxy-kynurenine [3HK] and 5-hydroxyindole acetic acid [5-HIAA]). The mothers received a 124-item questionnaire on features surrounding the pregnancy. (1) For children with ADHD, a shorter pregnancy and smaller birth weight were associated statistically with increased 3HK and IFN-γ and for obstetric problems with decreased TNF-α levels. (2) Maternal smoking related to decreasing kynurenine and increasing 3HK and S100B levels in ADHD children. Paternal smoking was associated with increased tryptophan in the controls and increased IL-6 levels in ADHD children. (3) The taking of supplements often related to decreasing TNF-α, increasing IL-10 and lower 5-HIAA levels in the ADHD children. Less 5-HIAA but more tryptophan was associated with earlier and later life events, respectively. (4) Increased IL-16 and 5-HIAA levels in the ADHD group related to reports of poorer infant health. Unexpectedly, more child care (seafood and time together) in ADHD than healthy families was implicated by lower tryptophan levels and an altered balance of pro-inflammatory cytokines. Across measures control families generally showed either non-significant associations or the opposite to those of the ADHD group. In ADHD children more than controls, the balance of potentially toxic or protective kynurenine metabolites and of pro- over anti-inflammatory cytokines may reflect the perinatal experience associated with stress, but not with maternal illness.