Corpus callosum in adolescent offspring exposed prenatally to maternal cigarette smoking

Prenatal influences on postnatal neuroplasticity: Integrating DOHaD and sensitive/critical period frameworks to understand biological embedding in early development

Early environments can have significant and lasting effects on brain, body, and behavior across the lifecourse. Here, we address current research efforts to understand how experiences impact neurodevelopment with a new perspective integrating two well-known conceptual frameworks - the Developmental Origins of Health and Disease (DOHaD) and sensitive/critical period frameworks. Specifically, we consider how prenatal experiences characterized in the DOHaD model impact two key neurobiological mechanisms of sensitive/critical periods for adapting to and learning from the postnatal environment. We draw from both animal and human research to summarize the current state of knowledge on how particular prenatal substance exposures (psychoactive substances and heavy metals) and nutritional profiles (protein-energy malnutrition and iron deficiency) each differentially impact brain circuits' excitation/GABAergic inhibition balance and myelination. Finally, we highlight new research directions that emerge from this integrated framework, including testing how prenatal environments alter sensitive/critical period timing and learning and identifying potential promotional/buffering prenatal exposures to impact postnatal sensitive/critical periods. We hope this integrative framework considering prenatal influences on postnatal neuroplasticity will stimulate new research to understand how early environments have lasting consequences on our brains, behavior, and health.

Investigating the Relationship Between Smoking Behavior and Global Brain Volume

Background

Previous studies have shown that brain volume is negatively associated with cigarette smoking, but there is an ongoing debate about whether smoking causes lowered brain volume or a lower brain volume is a risk factor for smoking. We address this debate through multiple methods that evaluate directionality: Bradford Hill's criteria, which are commonly used to understand a causal relationship in epidemiological studies, and mediation analysis.

Methods

In 32,094 participants of European descent from the UK Biobank dataset, we examined the relationship between a history of daily smoking and brain volumes, as well as an association of genetic risk score to ever smoking with brain volume.

Results

A history of daily smoking was strongly associated with decreased brain volume, and a history of heavier smoking was associated with a greater decrease in brain volume. The strongest association was between total gray matter volume and a history of daily smoking (effect size = -2964 mm3, p = 2.04 × 10-16), and there was a dose-response relationship with more pack years smoked associated with a greater decrease in brain volume. A polygenic risk score for smoking initiation was strongly associated with a history of daily smoking (effect size = 0.05, p = 4.20 × 10-84), but only modestly associated with total gray matter volume (effect size = -424 mm3, p = .01). Mediation analysis indicated that a history of daily smoking mediated the relationship between the smoking initiation polygenic risk score and total gray matter volume.

Conclusions

A history of daily smoking is strongly associated with a decreased total brain volume.

Transgenerational effects of maternal exposure to nicotine on structures of pituitary-gonadal axis of rats

Smoking can lead to several diseases and cause a reduction in fertility in men and women. Among the various components of cigarettes harmful during pregnancy, nicotine stands out. It can cause a reduction in placental blood flow, compromising the development of the baby with neurological, reproductive and endocrine consequences. Thus, we aimed to evaluate the effects of nicotine on the pituitary-gonadal axis of rats exposed during pregnancy and breastfeeding (1st generation - F1), and whether the possible damage observed would reach the 2nd generation (F2). Pregnant Wistar rats received 2 mg/kg/day of nicotine throughout the entire gestation and lactation. Part of the offspring was evaluated on the first neonatal day (F1) for macroscopic, histopathological and immunohistochemical analyses of brain and gonads. Another part of the offspring was kept until 90 days-old for mating and obtainment of progenies that had the same parameters evaluated at the end of pregnancy (F2). The occurrence of malformations was more frequent and diversified in nicotine-exposed F2. Brain alterations, including reduced size and changes in cell proliferation and death, were seen in both generations of nicotine-exposed rats. Male and female gonads of F1 exposed rats were also affected. The F2 rats showed reduced cellular proliferation and increased cell death on the pituitary and ovaries, besides increased anogenital distance in females. The number of mast cells was not enough altered to indicate an inflammatory process in brain and gonads. We conclude that prenatal exposure to nicotine causes transgenerational alterations in the structures of pituitary-gonadal axis in rats.

Electronic cigarettes and health outcomes: umbrella and systematic review of the global evidence

OBJECTIVE

To review and synthesise the global evidence regarding the health effects of electronic cigarettes (e-cigarettes, vapes).

STUDY DESIGN

Umbrella review (based on major independent reviews, including the 2018 United States National Academies of Sciences, Engineering, and Medicine [NASEM] report) and top-up systematic review of published, peer-reviewed studies in humans examining the relationship of e-cigarette use to health outcomes published since the NASEM report.

DATA SOURCES

Umbrella review: eight major independent reviews published 2017-2021. Systematic review: PubMed, MEDLINE, Scopus, Web of Science, the Cochrane Library, and PsycINFO (articles published July 2017 - July 2020 and not included in NASEM review).

DATA SYNTHESIS

Four hundred eligible publications were included in our synthesis: 112 from the NASEM review, 189 from our top-up review search, and 99 further publications cited by other reviews. There is conclusive evidence linking e-cigarette use with poisoning, immediate inhalation toxicity (including seizures), and e-cigarette or vaping product use-associated lung injury (EVALI; largely but not exclusively for e-liquids containing tetrahydrocannabinol and vitamin E acetate), as well as for malfunctioning devices causing injuries and burns. Environmental effects include waste, fires, and generation of indoor airborne particulate matter (substantial to conclusive evidence). There is substantial evidence that nicotine e-cigarettes can cause dependence or addiction in non-smokers, and strong evidence that young non-smokers who use e-cigarettes are more likely than non-users to initiate smoking and to become regular smokers. There is limited evidence that freebase nicotine e-cigarettes used with clinical support are efficacious aids for smoking cessation. Evidence regarding effects on other clinical outcomes, including cardiovascular disease, cancer, development, and mental and reproductive health, is insufficient or unavailable.

CONCLUSION

E-cigarettes can be harmful to health, particularly for non-smokers and children, adolescents, and young adults. Their effects on many important health outcomes are uncertain. E-cigarettes may be beneficial for smokers who use them to completely and promptly quit smoking, but they are not currently approved smoking cessation aids. Better quality evidence is needed regarding the health impact of e-cigarette use, their safety and efficacy for smoking cessation, and effective regulation.

REGISTRATION

Systematic review: PROSPERO, CRD42020200673 (prospective).

Association of Maternal Smoking during Pregnancy with Neurophysiological and ADHD-Related Outcomes in School-Aged Children

Data of a longitudinal cohort study were analyzed to investigate the association between prenatal tobacco exposure and electroencephalographical (EEG) power spectrum in healthy, school-aged children as well as its relationship with attention deficit hyperactivity disorder (ADHD)-related symptoms. Group comparisons (exposed, non-exposed) were performed to test whether prenatal tobacco exposure was associated with brain activity and ADHD symptoms, with adjustments made for covariates including child's sex, child's age, maternal age, maternal smoking habit before pregnancy, alcohol consumption during pregnancy, gestation age, and maternal psychopathology. Tobacco-exposed children showed higher brain activity in the delta and theta frequency bands. This effect was independent of the considered covariates. However, the effects on hyperactivity were found to significantly depend on maternal age and alcohol consumption during pregnancy, but not on the amount of exposure. In summary, smoking during pregnancy significantly affected the resting-state brain activity in children, independent of socio-demographic factors, indicating potential long-lasting effects on brain development. Its impact on ADHD-related behavior was shown to be influenced by socio-demographic confounding factors, such as maternal alcohol consumption and the age of the mother.

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.

Risk of lead exposure, subcortical brain structure, and cognition in a large cohort of 9- to 10-year-old children

BACKGROUND

Lead, a toxic metal, affects cognitive development at the lowest measurable concentrations found in children, but little is known about its direct impact on brain development. Recently, we reported widespread decreases in cortical surface area and volume with increased risks of lead exposure, primarily in children of low-income families.

METHODS AND FINDINGS

We examined associations of neighborhood-level risk of lead exposure with cognitive test performance and subcortical brain volumes. We also examined whether subcortical structure mediated associations between lead risk and cognitive performance. Our analyses employed a cross-sectional analysis of baseline data from the observational Adolescent Brain Cognitive Development (ABCD) Study. The multi-center ABCD Study used school-based enrollment to recruit a demographically diverse cohort of almost 11,900 9- and 10-year-old children from an initial 22 study sites. The analyzed sample included data from 8,524 typically developing child participants and their parents or caregivers. The primary outcomes and measures were subcortical brain structure, cognitive performance using the National Institutes of Health Toolbox, and geocoded risk of lead exposure. Children who lived in neighborhoods with greater risks of environmental lead exposure exhibited smaller volumes of the mid-anterior (partial correlation coefficient [rp] = -0.040), central (rp = -0.038), and mid-posterior corpus callosum (rp = -0.035). Smaller volumes of these three callosal regions were associated with poorer performance on cognitive tests measuring language and processing speed. The association of lead exposure risk with cognitive performance was partially mediated through callosal volume, particularly the mid-posterior corpus callosum. In contrast, neighborhood-level indicators of disadvantage were not associated with smaller volumes of these brain structures.

CONCLUSIONS

Environmental factors related to the risk of lead exposure may be associated with certain aspects of cognitive functioning via diminished subcortical brain structure, including the anterior splenium (i.e., mid-posterior corpus callosum).

Epigenome-wide change and variation in DNA methylation in childhood: trajectories from birth to late adolescence

DNA methylation (DNAm) is known to play a pivotal role in childhood health and development, but a comprehensive characterization of genome-wide DNAm trajectories across this age period is currently lacking. We have therefore performed a series of epigenome-wide association studies in 5019 blood samples collected at multiple time-points from birth to late adolescence from 2348 participants of two large independent cohorts. DNAm profiles of autosomal CpG sites (CpGs) were generated using the Illumina Infinium HumanMethylation450 BeadChip. Change over time was widespread, observed at over one-half (53%) of CpGs. In most cases, DNAm was decreasing (36% of CpGs). Inter-individual variation in linear trajectories was similarly widespread (27% of CpGs). Evidence for non-linear change and inter-individual variation in non-linear trajectories was somewhat less common (11 and 8% of CpGs, respectively). Very little inter-individual variation in change was explained by sex differences (0.4% of CpGs) even though sex-specific DNAm was observed at 5% of CpGs. DNAm trajectories were distributed non-randomly across the genome. For example, CpGs with decreasing DNAm were enriched in gene bodies and enhancers and were annotated to genes enriched in immune-developmental functions. In contrast, CpGs with increasing DNAm were enriched in promoter regions and annotated to genes enriched in neurodevelopmental functions. These findings depict a methylome undergoing widespread and often non-linear change throughout childhood. They support a developmental role for DNA methylation that extends beyond birth into late adolescence and has implications for understanding life-long health and disease. DNAm trajectories can be visualized at http://epidelta.mrcieu.ac.uk.

Sex-specific alterations in GABA receptor-mediated responses in laterodorsal tegmentum are associated with prenatal exposure to nicotine

Smoking during pregnancy is associated with deleterious physiological and cognitive effects on the offspring, which are likely due to nicotine-induced alteration in the development of neurotransmitter systems. Prenatal nicotine exposure (PNE) in rodents is associated with changes in behaviors controlled in part by the pontine laterodorsal tegmentum (LDT), and LDT excitatory signaling is altered in a sex and age-dependent manner by PNE. As effects on GABAergic LDT signaling are unknown, we used calcium imaging to evaluate GABA_A receptor- (GABA_A R as well as GABA_A -_ρ R) and GABA_B receptor (GABA_B R)-mediated calcium responses in LDT brain slices from female and male PNE mice in two different age groups. Overall, in older PNE females, changes in calcium induced by stimulation of GABA_A R and GABA_B R, including GABA_A -_ρ R were shifted toward calcium rises. In both young and old males, PNE was associated with alterations in calcium mediated by all three receptors; however, the GABA_A R was the most affected. These results show for the first time that PNE is associated with alterations in GABAergic transmission in the LDT in a sex- and age-dependent manner, and these data are the first to show PNE-associated alterations in functionality of GABA receptors in any nucleus. PNE-associated alterations in LDT GABAergic transmission within the LDT would be expected to alter output to target regions and could play a role in LDT-implicated, negative behavioral outcomes following gestational exposure to smoking. Accordingly, our data provide further supportive evidence of the importance of eliminating the consumption of nicotine during pregnancy.

Prenatal exposure to maternal cigarette smoking and structural properties of the human corpus callosum

Alterations induced by prenatal exposure to nicotine have been observed in experimental (rodent) studies. While numerous developmental outcomes have been associated with prenatal exposure to maternal cigarette smoking (PEMCS) in humans, the possible relation with brain structure is less clear. Here we sought to elucidate the relation between PEMCS and structural properties of human corpus callosum in adolescence and early adulthood in a total of 1,747 youth. We deployed three community-based cohorts of 446 (age 25-27 years, 46% exposed), 934 (age 12-18 years, 47% exposed) and 367 individuals (age 18-21 years, 9% exposed). A mega-analysis revealed lower mean diffusivity in the callosal segments of exposed males. We speculate that prenatal exposure to maternal cigarette smoking disrupts the early programming of callosal structure and increases the relative portion of small-diameter fibres.

Two Lifestyle Risks Intertwined: Parental Smoking Predicts Child Gambling Behavior at Age 12 Years

BACKGROUND

Parental smoking can create a toxic environment for child development. A parental smoking lifestyle can predispose children to executive deficits, influencing precocious risk activities. Using a prospective birth cohort design, we examine the association between 2 lifestyle factors by estimating the relative contribution of long-term parental household smoking in predicting subsequent precocious child gambling behavior.

METHOD

Parents reported on the amount of household smoke exposure from ages 1.5 to 7.5 years for children from the Quebec Longitudinal Study of Child Development. The main outcome measure was children's self-report of gambling behavior (at age 12 years).

RESULTS

Sixty percent of parents reported that their children were never exposed to secondhand smoke in the home, while 27% and 13% reported transient and continuous levels of secondhand smoke, respectively. Overall, 16% of children reported gambling participation. When compared with never-exposed children, children exposed to secondhand smoke had 18% more chances of having participated in gambling at age 12 years (odds ratio = 1.18; 95% CI = 1.080-1.293). These results are adjusted for competing explanations and possible individual and family confounders.

CONCLUSIONS

Higher levels of early childhood household smoke exposure are associated with greater odds of reporting gambling participation at age 12 years, which is more than several years before it is normative youthful behavior. By connecting the neurotoxic influence of one lifestyle factor on another, we show a nontrivial link between 2 public health issues (smoke exposure and precocious gambling) associated with considerable individual and societal costs that are amenable to community information campaigns.

The cellular basis of fetal endoplasmic reticulum stress and oxidative stress in drug-induced neurodevelopmental deficits

Prenatal substance exposure is a growing public health concern worldwide. Although the opioid crisis remains one of the most prevalent addiction problems in our society, abuse of cocaine, methamphetamines, and other illicit drugs, particularly amongst pregnant women, are nonetheless significant and widespread. Evidence demonstrates prenatal drug exposure can affect fetal brain development and thus can have long-lasting impact on neurobehavioral and cognitive performance later in life. In this review, we highlight research examining the most prevalent drugs of abuse and their effects on brain development with a focus on endoplasmic reticulum stress and oxidative stress signaling pathways. A thorough exploration of drug-induced cellular stress mechanisms during prenatal brain development may provide insight into therapeutic interventions to combat effects of prenatal drug exposure.

Within-Family Effects of Smoking during Pregnancy on ADHD: the Importance of Phenotype

We sought to test within- and between- family associations of smoking during pregnancy (SDP) and attention deficit-hyperactivity disorder (ADHD) symptoms using a structured interview based on the conventional Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) symptoms and the Strengths and Weaknesses of ADHD-Symptoms and Normal-Behavior (SWAN) scale, which is a population based measure that grew out of the notion that an ADHD diagnosis exists on the extreme end of a continuum of normative behaviors and includes both above- and below- average performance on attention and activity. We used a sibling-comparison approach in a sample of 173 families including siblings aged 7-16 years (52% male) drawn from the state of Missouri, USA, wherein mothers smoked during one pregnancy but not the other. There was a within-family effect of smoking during pregnancy on SWAN hyperactivity/impulsivity and SWAN total ADHD behaviors. The associations between SDP and DSM-IV-based ADHD symptom dimensions as well as SWAN inattention were explained by familial confounds. These findings suggest that SDP exerts a potentially causal effect on increased ADHD hyperactive/impulsive behaviors and that this SDP effect is best captured when hyperactivity/impulsivity is assessed more normatively across the population, rather than specifically assessing problematic behaviors via DSM symptoms. Thus, any potentially causal effect of SDP on ADHD symptom dimensions may be restricted to hyperactive/impulsive behaviors rather than inattention, and normative, non-DSM-IV based behavioral measures may provide a more sensitive test of mechanisms of SDP-ADHD symptom associations, particularly in non-clinical samples.

Reductions in Corpus Callosum Volume Partially Mediate Effects of Prenatal Alcohol Exposure on IQ

Disproportionate volume reductions in the basal ganglia, corpus callosum (CC) and hippocampus have been reported in children with prenatal alcohol exposure (PAE). However, few studies have investigated these reductions in high prevalence communities, such as the Western Cape Province of South Africa, and only one study made use of manual tracing, the gold standard of volumetric analysis. The present study examined the effects of PAE on subcortical neuroanatomy using manual tracing and the relation of volumetric reductions in these regions to IQ and performance on the California Verbal Learning Test-Children's Version (CVLT-C), a list learning task sensitive to PAE. High-resolution T1-weighted images were acquired, using a sequence optimized for morphometric neuroanatomical analysis, on a Siemens 3T Allegra MRI scanner from 71 right-handed, 9- to 11-year-old children [9 fetal alcohol syndrome (FAS), 19 partial FAS (PFAS), 24 non-syndromal heavily exposed (HE) and 19 non-exposed controls]. Frequency of maternal drinking was ascertained prospectively during pregnancy using timeline follow-back interviews. PAE was examined in relation to volumes of the CC and left and right caudate nuclei, nucleus accumbens and hippocampi. All structures were manually traced using Multitracer. Higher levels of PAE were associated with reductions in CC volume after adjustment for TIV. Although the effect of PAE on CC was confounded with smoking and lead exposure, additional analyses showed that it was not accounted for by these exposures. Amongst dysmorphic children, smaller CC was associated with poorer IQ and CVLT-C scores and statistically mediated the effect of PAE on IQ. In addition, higher levels of PAE were associated with bilateral volume reductions in caudate nuclei and hippocampi, effects that remained significant after control for TIV, child sex and age, socioeconomic status, maternal smoking during pregnancy, and childhood lead exposure. These data confirm previous findings showing that PAE is associated with decreases in subcortical volumes and is the first study to show that decreases in callosal volume may play a role in fetal alcohol-related impairment in cognitive function seen in childhood.

Human Brain Abnormalities Associated With Prenatal Alcohol Exposure and Fetal Alcohol Spectrum Disorder

Fetal alcohol spectrum disorder (FASD) is a common neurodevelopmental problem, but neuropathologic descriptions are rare and focused on the extreme abnormalities. We conducted a retrospective survey (1980–2016) of autopsies on 174 individuals with prenatal alcohol exposure or an FASD diagnosis. Epidemiologic details and neuropathologic findings were categorized into 5 age groups. Alcohol exposure was difficult to quantify. When documented, almost all mothers smoked tobacco, many abused other substances, and prenatal care was poor or nonexistent. Placental abnormalities were common (68%) in fetal cases. We identified micrencephaly (brain weight <5th percentile) in 31, neural tube defects in 5, isolated hydrocephalus in 6, corpus callosum defects in 6 (including some with complex anomalies), probable prenatal ischemic lesions in 5 (excluding complications of prematurity), minor subarachnoid heterotopias in 4, holoprosencephaly in 1, lissencephaly in 1, and cardiac anomalies in 26 cases. The brain abnormalities associated with prenatal alcohol exposure are varied; cause–effect relationships cannot be determined. FASD is likely not a monotoxic disorder. The animal experimental literature, which emphasizes controlled exposure to ethanol alone, is therefore inadequate. Prevention must be the main societal goal, however, a clear understanding of the neuropathology is necessary for provision of care to individuals already affected.

Prospective longitudinal associations between household smoke exposure in early childhood and antisocial behavior at age 12

Young children exert little control over household tobacco smoke exposure, which is considered a developmental neurotoxicant. Using the Quebec Longitudinal Study birth cohort, we examine prospective associations between early childhood smoke exposure and later antisocial behavior. Parents of 1035 children reported on the presence of household smokers at seven follow-ups from ages 1.5 to 7.5. At age 12, children self-reported on five aspects of early antisocial dispositions. After adjusting for confounders, every standard deviation increase in household smoke exposure was prospectively associated with a 19% standard deviation unit increase in conduct problems (β=0.07; 95% confidence interval [CI] from 0.04 to 0.09), a 11% standard deviation unit increase in proactive aggression (β=0.04; 95% CI from 0.01 to 0.07), a 13% standard deviation unit increase in reactive aggression (β=0.07; 95% CI from 0.03 to 0.12), a 14% standard deviation unit increase in school indiscipline (β=0.13; 95% CI from 0.05 to 0.20), and a 10% standard deviation unit increase in dropout risk (β=0.07; 95% CI from 0.01 to 0.12). These long-term findings warrant fostering parental awareness of developmental risks by policy-makers/health practitioners. School curricula can equally integrate these ideas into their curriculum.

Cohort Profile: The Saguenay Youth Study (SYS)

The Saguenay Youth Study (SYS) is a two-generational study of adolescents and their parents (n = 1029 adolescents and 962 parents) aimed at investigating the aetiology, early stages and trans-generational trajectories of common cardiometabolic and brain diseases. The ultimate goal of this study is to identify effective means for increasing healthy life expectancy. The cohort was recruited from the genetic founder population of the Saguenay Lac St Jean region of Quebec, Canada. The participants underwent extensive (15-h) phenotyping, including an hour-long recording of beat-by-beat blood pressure, magnetic resonance imaging of the brain and abdomen, and serum lipidomic profiling with LC-ESI-MS. All participants have been genome-wide genotyped (with ∼ 8 M imputed single nucleotide polymorphisms) and a subset of them (144 adolescents and their 288 parents) has been genome-wide epityped (whole blood DNA, Infinium HumanMethylation450K BeadChip). These assessments are complemented by a detailed evaluation of each participant in a number of domains, including cognition, mental health and substance use, diet, physical activity and sleep, and family environment. The data collection took place during 2003-12 in adolescents (full) and their parents (partial), and during 2012-15 in parents (full). All data are available upon request.

Developmental toxicity of nicotine: A transdisciplinary synthesis and implications for emerging tobacco products

While the health risks associated with adult cigarette smoking have been well described, effects of nicotine exposure during periods of developmental vulnerability are often overlooked. Using MEDLINE and PubMed literature searches, books, reports and expert opinion, a transdisciplinary group of scientists reviewed human and animal research on the health effects of exposure to nicotine during pregnancy and adolescence. A synthesis of this research supports that nicotine contributes critically to adverse effects of gestational tobacco exposure, including reduced pulmonary function, auditory processing defects, impaired infant cardiorespiratory function, and may contribute to cognitive and behavioral deficits in later life. Nicotine exposure during adolescence is associated with deficits in working memory, attention, and auditory processing, as well as increased impulsivity and anxiety. Finally, recent animal studies suggest that nicotine has a priming effect that increases addiction liability for other drugs. The evidence that nicotine adversely affects fetal and adolescent development is sufficient to warrant public health measures to protect pregnant women, children, and adolescents from nicotine exposure.

Cigarette smoke and related risk factors in neurological disorders: An update

Cigarette smoking is known to be harmful to health, and is considered the main cause of death worldwide, especially in India. Among the well-distinguished diseases related to smoking are, chronic obstructive pulmonary disease, oral and peripheral cancers, and cardiovascular complications. However, the impact of cigarette smoking on neurocognitive and neuropathological effects, including anxiety, Alzheimer's disease, Parkinson's disease, ischemic stroke, and blood-brain barrier dysfunction, still remains unclear. Cigarette smoke consists of more than 4500 toxic chemicals that combine to form free radicals, which lead to oxidative stress-associated neurological disorders. Herein, we discuss the role of antioxidant agents in delaying or attenuating disease complications. In addition, in this review, we discuss the neuropathological effect of cigarette smoke and its interference in neurodegeneration.

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.

QF2011: a protocol to study the effects of the Queensland flood on pregnant women, their pregnancies, and their children's early development

BACKGROUND

Retrospective studies suggest that maternal exposure to a severe stressor during pregnancy increases the fetus' risk for a variety of disorders in adulthood. Animal studies testing the fetal programming hypothesis find that maternal glucocorticoids pass through the placenta and alter fetal brain development, particularly the hypothalamic-pituitary-adrenal axis. However, there are no prospective studies of pregnant women exposed to a sudden-onset independent stressor that elucidate the biopsychosocial mechanisms responsible for the wide variety of consequences of prenatal stress seen in human offspring. The aim of the QF2011 Queensland Flood Study is to fill this gap, and to test the buffering effects of Midwifery Group Practice, a form of continuity of maternity care.

METHODS/DESIGN

In January 2011 Queensland, Australia had its worst flooding in 30 years. Simultaneously, researchers in Brisbane were collecting psychosocial data on pregnant women for a randomized control trial (the M@NGO Trial) comparing Midwifery Group Practice to standard care. We invited these and other pregnant women to participate in a prospective, longitudinal study of the effects of prenatal maternal stress from the floods on maternal, perinatal and early childhood outcomes. Data collection included assessment of objective hardship and subjective distress from the floods at recruitment and again 12 months post-flood. Biological samples included maternal bloods at 36 weeks pregnancy, umbilical cord, cord blood, and placental tissues at birth. Questionnaires assessing maternal and child outcomes were sent to women at 6 weeks and 6 months postpartum. The protocol includes assessments at 16 months, 2½ and 4 years. Outcomes include maternal psychopathology, and the child's cognitive, behavioral, motor and physical development. Additional biological samples include maternal and child DNA, as well as child testosterone, diurnal and reactive cortisol.

DISCUSSION

This prenatal stress study is the first of its kind, and will fill important gaps in the literature. Analyses will determine the extent to which flood exposure influences the maternal biological stress response which may then affect the maternal-placental-fetal axis at the biological, biochemical, and molecular levels, altering fetal development and influencing outcomes in the offspring. The role of Midwifery Group Practice in moderating effects of maternal stress will be tested.

The pediatric template of brain perfusion

Magnetic resonance imaging (MRI) captures the dynamics of brain development with multiple modalities that quantify both structure and function. These measurements may yield valuable insights into the neural patterns that mark healthy maturation or that identify early risk for psychiatric disorder. The Pediatric Template of Brain Perfusion (PTBP) is a free and public neuroimaging resource that will help accelerate the understanding of childhood brain development as seen through the lens of multiple modality neuroimaging and in relation to cognitive and environmental factors. The PTBP uses cross-sectional and longitudinal MRI to quantify cortex, white matter, resting state functional connectivity and brain perfusion, as measured by Arterial Spin Labeling (ASL), in 120 children 7-18 years of age. We describe the PTBP and show, as a demonstration of validity, that global summary measurements capture the trajectories that demarcate critical turning points in brain maturation. This novel resource will allow a more detailed understanding of the network-level, structural and functional landmarks that are obtained during normal adolescent brain development.

Saguenay Youth Study: a multi-generational approach to studying virtual trajectories of the brain and cardio-metabolic health

This paper provides an overview of the Saguenay Youth Study (SYS) and its parental arm. The overarching goal of this effort is to develop trans-generational models of developmental cascades contributing to the emergence of common chronic disorders, such as depression, addictions, dementia and cardio-metabolic diseases. Over the past 10 years, we have acquired detailed brain and cardio-metabolic phenotypes, and genome-wide genotypes, in 1029 adolescents recruited in a population with a known genetic founder effect. At present, we are extending this dataset to acquire comparable phenotypes and genotypes in the biological parents of these individuals. After providing conceptual background for this work (transactions across time, systems and organs), we describe briefly the tools employed in the adolescent arm of this cohort and highlight some of the initial accomplishments. We then outline in detail the phenotyping protocol used to acquire comparable data in the parents.

Maternal cigarette smoking during pregnancy predicts drug use via externalizing behavior in two community-based samples of adolescents

BACKGROUND AND AIMS

Prenatal exposure to maternal cigarette smoking (PEMCS) is associated with a higher probability of substance use in adolescence. We explore if externalizing behavior mediates this relationship, while controlling for a number of potential covariates of this mediation process.

METHODS

We used data obtained in two geographically distinct community samples of adolescents. The first (cross-sectional) sample consisted of 996 adolescents (12-18 years of age) recruited from the Saguenay Youth Study (SYS) in Canada (47% with PEMCS). The second (longitudinal) sample consisted of 1141 adolescents (49% with PEMCS) from the Northern Finland Birth Cohort (NFBC1986). In both samples, externalizing behavior and substance use were assessed during adolescence. In the NFBC1986 cohort, externalizing behavior was also assessed in childhood.

RESULTS

In both populations, PEMCS is associated with a higher likelihood of adolescent drug experimentation. In the NFBC1986 cohort, exposed (versus non-exposed) adolescents experiment with an extra 1.27 [B = 0.24, 95% confidence intervals (CI) = 0.15, 0.33 P < 0.001] drugs. In the SYS cohort, a clear protective effect of not being exposed is shown: non-exposed (versus exposed) adolescents are 1.5 times [B = -0.42, 95% CI = -0.75, -0.09, P = 0.013] less likely to take drugs. These associations between PEMCS and drug experimentation remain in the multivariate and mediational analyses.

CONCLUSIONS

Prenatal exposure to maternal cigarette smoking appears to be associated with a higher probability of experimenting with drugs during adolescence, both directly and indirectly via externalizing behavior and the number of peers reported as using drugs.

Prenatal tobacco exposure and brain morphology: a prospective study in young children

It is well known that smoking during pregnancy can affect offspring health. Prenatal tobacco exposure has been associated with negative behavioral and cognitive outcomes in childhood, adolescence, and young adulthood. These associations between prenatal tobacco exposure and psychopathology in offspring could possibly be explained by the influence of prenatal tobacco exposure on brain development. In this prospective study, we investigated the association between prenatal tobacco exposure, behavioral and emotional functioning and brain morphology in young children. On the basis of age and gender, we matched 113 children prenatally exposed to tobacco with 113 unexposed controls. These children were part of a population-based study in the Netherlands, the Generation R Study, and were followed from pregnancy onward. Behavioral and emotional functioning was assessed at age 6 with the Child Behavior Checklist. We assessed brain morphology using magnetic resonance imaging techniques in children aged 6-8 years. Children exposed to tobacco throughout pregnancy have smaller total brain volumes and smaller cortical gray matter volumes. Continued prenatal tobacco exposure was associated with cortical thinning, primarily in the superior frontal, superior parietal, and precentral cortices. These children also demonstrated increased scores of affective problems. In addition, thickness of the precentral and superior frontal cortices was associated with affective problems. Importantly, brain development in offspring of mothers who quit smoking during pregnancy resembled that of nonexposed controls (no smaller brain volumes and no thinning of the cortex). Our findings suggest an association between continued prenatal tobacco exposure and brain structure and function in school-aged children.

Neuropathology of cigarette smoking

It is well established that cigarette smoking is hazardous to health and is a risk factor for many chronic diseases. However, its impact on the brain, whether it be from prenatal exposure to maternal cigarette smoking, cerebrovascular disease, Alzheimer's disease (AD) or Parkinson's disease, is still not very clear. Neuroimaging and neuropathological investigations suggest that there are heterogeneous effects of cigarette smoking on the brain. On the one hand, it is quite clear that cigarette smoking causes damage to endothelial cells, resulting in increased risk of cerebrovascular disease. On the other hand, it seems to be associated with different Alzheimer's pathologies in post-mortem brains and experimental models, despite the fact that epidemiological studies clearly indicate a positive correlation between cigarette smoking and increased risk for AD. Interestingly, cigarette smoking appears to be associated with reduced Parkinson's pathology in post-mortem brains. However, although nicotine in cigarettes may have some neuroprotective actions, the effects of all the other toxic compounds in cigarettes cannot be ignored. It is, therefore, our aim to summarize what is known about the neuropathology of cigarette smoking and, in particular, its implications for neurodegenerative diseases.

Maternal smoking during pregnancy and fetal organ growth: a magnetic resonance imaging study

Objective

To study whether maternal cigarette smoking during pregnancy is associated with alterations in the growth of fetal lungs, kidneys, liver, brain, and placenta.

Design

A case-control study, with operators performing the image analysis blinded.

Setting

Study performed on a research-dedicated magnetic resonance imaging (MRI) scanner (1.5 T) with participants recruited from a large teaching hospital in the United Kingdom.

Participants

A total of 26 pregnant women (13 current smokers, 13 non smokers) were recruited; 18 women (10 current smokers, 8 nonsmokers) returned for the second scan later in their pregnancy.

Methods

Each fetus was scanned with MRI at 22–27 weeks and 33–38 weeks gestational age (GA).

Main outcome measures

Images obtained with MRI were used to measure volumes of the fetal brain, kidneys, lungs, liver and overall fetal size, as well as placental volumes.

Results

Exposed fetuses showed lower brain volumes, kidney volumes, and total fetal volumes, with this effect being greater at visit 2 than at visit 1 for brain and kidney volumes, and greater at visit 1 than at visit 2 for total fetal volume. Exposed fetuses also demonstrated lower lung volume and placental volume, and this effect was similar at both visits. No difference was found between the exposed and nonexposed fetuses with regards to liver volume.

Conclusion

Magnetic resonance imaging has been used to show that maternal smoking is associated with reduced growth of fetal brain, lung and kidney; this effect persists even when the volumes are corrected for maternal education, gestational age, and fetal sex. As expected, the fetuses exposed to maternal smoking are smaller in size. Similarly, placental volumes are smaller in smoking versus nonsmoking pregnant women.

Prenatal adversity: a risk factor in borderline personality disorder?

BACKGROUND

Patients with borderline personality disorder (BPD) show a high prevalence of early adversity, such as childhood trauma. It has also been reported that prenatal adverse conditions, such as prenatal maternal stress, drug taking, tobacco smoking or medical complications, may be associated with an increased risk of mental disorders in the offspring. Prenatal adversity is investigated here for the first time as a potential risk factor in the diagnosis of BPD. Method A total of 100 patients with a DSM-IV diagnosis of BPD and 100 matched healthy controls underwent semi-structured interviews about the course of pregnancy, maternal stressors, birth complications and childhood trauma. Further information was obtained from the participants' mothers and from prenatal medical records.

RESULTS

Borderline patients were significantly more often exposed to adverse intrauterine conditions, such as prenatal tobacco exposure (p=0.004), medical complications (p=0.008), prenatal maternal traumatic stress (p=0.015), familial conflicts (p=0.004), low social support (p=0.004) and partnership problems during pregnancy (p=0.014). Logistic regression analyses revealed that the reported prenatal risk factors accounted for 25.7% of the variance in BPD. Prenatal tobacco exposure [odds ratio (OR) 3.37, 95% confidence interval (CI) 1.49-7.65, p=0.004] and medical complications (OR 2.87, 95% CI 1.29-6.38, p=0.010) emerged as important predictors. After controlling for childhood adversity and parental socio-economic status (SES), prenatal risk factors predicted relevant borderline subdomains, such as impulsivity, affective instability, identity disturbance, dissociation and severity of borderline symptoms.

CONCLUSIONS

This study provides evidence of an association between prenatal adversity and the diagnosis of BPD. Our findings suggest that prenatal adversity may constitute a potential risk factor in the pathogenesis of BPD.

A comparative, developmental, and clinical perspective of neurobehavioral sexual dimorphisms

Women and men differ in a wide variety of behavioral traits and in their vulnerability to developing certain mental disorders. This review endeavors to explore how recent preclinical and clinical research findings have enhanced our understanding of the factors that underlie these disparities. We start with a brief overview of some of the important genetic, molecular, and hormonal determinants that contribute to the process of sexual differentiation. We then discuss the importance of animal models in studying the mechanisms responsible for sex differences in neuropsychiatric disorders (e.g., drug dependence) - with a special emphasis on experimental models based on the neurodevelopmental and "three hits" hypotheses. Next, we describe the most common brain phenotypes observed in vivo with magnetic resonance imaging. We discuss the challenges in interpreting these phenotypes vis-à-vis the underlying neurobiology and revisit the known sex differences in brain structure from birth, through adolescence, and into adulthood. This is followed by a presentation of pertinent clinical and epidemiological data that point to important sex differences in the prevalence, course, and expression of psychopathologies such as schizophrenia, and mood disorders including major depression and posttraumatic stress disorder. Recent evidence implies that mood disorders and psychosis share some common genetic predispositions and neurobiological bases. Therefore, modern research is emphasizing dimensional representation of mental disorders and conceptualization of schizophrenia and major depression as a continuum of cognitive deficits and neurobiological abnormalities. Herein, we examine available evidence on cerebral sexual dimorphism to verify if sex differences vary quantitatively and/or qualitatively along the psychoses-depression continuum. Finally, sex differences in the prevalence of posttraumatic disorder and drug abuse have been described, and we consider the genomic and molecular data supporting these differences.

Prenatal exposure to cigarette smoke or alcohol and cerebellum volume in attention-deficit/hyperactivity disorder and typical development

Prenatal exposure to teratogenic substances, such as nicotine or alcohol, increases the risk of developing attention-deficit/hyperactivity disorder (ADHD). To date, studies examining this relationship have used symptom scales as outcome measures to assess the effect of prenatal exposure, and have not investigated the neurobiological pathways involved. This study explores the effect of prenatal exposure to cigarettes or alcohol on brain volume in children with ADHD and typically developing controls. Children with ADHD who had been exposed prenatally to either substance were individually matched to children with and without ADHD who had not been. Controls who had been exposed prenatally were also individually matched to controls who had not been. For prenatal exposure to both smoking and alcohol, we found a pattern where subjects with ADHD who had been exposed had the smallest brain volumes and unexposed controls had the largest, with intermediate volumes for unexposed subjects with ADHD. This effect was most pronounced for cerebellum. A similar reduction fell short of significance for controls who had been exposed to cigarettes, but not alcohol. Our results are consistent with an additive effect of prenatal exposure and ADHD on brain volume, with the effects most pronounced for cerebellum.

Maternal smoking during pregnancy and offspring brain structure and function: review and agenda for future research

INTRODUCTION

Maternal smoking during pregnancy (MSDP) has been associated with long-term neurobehavioral and cognitive deficits in offspring. Animal models demonstrate alterations in brain structure and function following prenatal nicotine exposure. However, few studies have assessed the relationship between MSDP and brain development in humans. Therefore, the aims of this review are (a) to synthesize findings from the small number of human studies investigating effects of MSDP on offspring brain development and (b) to outline an agenda for future research in this nascent area.

METHODS

We searched MEDLINE and Psychinfo databases for human studies of MSDP and offspring brain structure and/or function.

RESULTS

Eleven studies meeting our search criteria were identified; 6 studies investigated effects of MSDP on brain structure; 5 examined effects on brain function. Across studies, MSDP was associated with decreased volume/thickness of the cerebellum and corpus callosum, increased auditory brainstem responses, and lack of coordination across brain regions during information and auditory processing.

CONCLUSIONS

Results from the small number of human studies revealed effects of MSDP on brain structure and function, highlighting potential neural pathways linking MSDP and offspring neurobehavioral and cognitive deficits. Given the limited amount of research in this area, we propose an agenda for future research. Gold standard studies would utilize longitudinal designs, integrated biological and maternal report measures of MSDP, and repeated measures of brain structure/function and neurobehavioral deficits across key developmental periods.

KCTD8 gene and brain growth in adverse intrauterine environment: a genome-wide association study

The most dramatic growth of the human brain occurs in utero and during the first 2 years of postnatal life. Genesis of the cerebral cortex involves cell proliferation, migration, and apoptosis, all of which may be influenced by prenatal environment. Here, we show that variation in KCTD8 (potassium channel tetramerization domain 8) is associated with brain size in female adolescents (rs716890, P = 5.40 × 10(-09)). Furthermore, we found that the KCTD8 locus interacts with prenatal exposure to maternal cigarette smoking vis-à-vis cortical area and cortical folding: In exposed girls only, the KCTD8 locus explains up to 21% of variance. Using head circumference as a proxy of brain size at 7 years of age, we have replicated this gene-environment interaction in an independent sample. We speculate that KCTD8 might modulate adverse effects of smoking during pregnancy on brain development via apoptosis triggered by low intracellular levels of potassium, possibly reducing the number of progenitor cells.

Neurobiological and behavioral stress reactivity in children prenatally exposed to tobacco

This study examined neurobiological and behavioral stress reactivity in children who had been prenatally exposed to tobacco. Neurobiological stress reactivity was measured using salivary cortisol and alpha-amylase levels at five different time points throughout a stressful neuropsychological test session, which involved a competition against a videotaped opponent. Participants (mean age: 10.6 years, SD 1.3) were 14 prenatally exposed (PE) children, 9 children with disruptive behavior problems (DBD), and 15 normal controls (NC). For cortisol responses, no significant differences between the three groups were observed. Normal controls, however, had significantly higher alpha-amylase levels than PE-children throughout the test session, and their alpha-amylase levels also increased throughout the session, whereas these remained low and stable for PE-children. Alpha-amylase levels and trajectory of PE-children were similar to those observed for DBD-children. PE-children also showed significantly increased behavioral stress reactivity compared to NC-children, and neurobiological and behavioral stress reactivity were inversely related in PE-children, again similar to what was observed for DBD-children. These results support the hypothesis that prenatal smoking may lead to long-lasting neurobiological and behavioral changes in exposed offspring.

Understanding specific effects of prenatal alcohol exposure on brain structure in young adults

Prenatal alcohol exposure (PAE) is associated with various adverse effects on human brain and behavior. Recently, neuroimaging studies have begun to identify PAE effects on specific brain structures. Investigation of such specific PAE effects is important for understanding the teratogenic mechanism of PAE on human brain, which is critical for differentiating PAE from other disorders. In this structural MRI study with young adults, PAE effects on the volumes of automatically segmented cortical and subcortical regions of interest (ROIs) were evaluated both through a group difference approach and a parametric approach. In the group difference approach (comparing among two PAE and a control groups), a disproportionate PAE effect was found in several occipital and temporal regions. This result is inconsistent with previous studies with child samples. Moreover, a gender difference in PAE effect was shown in some cortical ROIs. These findings suggest that sampling and gender may be important factors for interpreting specific PAE effects on human brain. With the parametric approach, it was demonstrated that the higher the PAE level, the smaller the entire brain, the lower the IQ. Several cortical and subcortical ROIs also exhibited a negative correlation between the PAE level and ROI volume. Furthermore, our data showed that the PAE effect on the brain could not be interpreted by the PAE effect on general physical growth until the young adult age. This study provides valuable insight into specific effects of PAE on human brain and suggests important implications for future studies in this field.

Imaging the impact of prenatal alcohol exposure on the structure of the developing human brain

Prenatal alcohol exposure has numerous effects on the developing brain, including damage to selective brain structure. We review structural magnetic resonance imaging (MRI) studies of brain abnormalities in subjects prenatally exposed to alcohol. The most common findings include reduced brain volume and malformations of the corpus callosum. Advanced methods have been able to detect shape, thickness and displacement changes throughout multiple brain regions. The teratogenic effects of alcohol appear to be widespread, affecting almost the entire brain. The only region that appears to be relatively spared is the occipital lobe. More recent studies have linked cognition to the underlying brain structure in alcohol-exposed subjects, and several report patterns in the severity of brain damage as it relates to facial dysmorphology or to extent of alcohol exposure. Future studies exploring relationships between brain structure, cognitive measures, dysmorphology, age, and other variables will be valuable for further comprehending the vast effects of prenatal alcohol exposure and for evaluating possible interventions.

Difference between smokers and non-smokers in the corpus callosum volume

The purpose of this study was to analyze the effects of smoking on corpus callosum volume. In addition, the relationships between smoking duration, smoking frequency, and corpus callosum volume were analyzed. Magnetic resonance brain images were acquired for 58 normal Korean men (30 smokers (age 32.82±14.12 years) and 28 non-smokers (age 35.49±13.11 years)). The corpus callosum volume was measured using Brain Voyager 2000S/W and was normalized by intracranical volume, which was calculated using cerebral sizes. The corpus callosum volume for smokers was significantly smaller than that for non-smokers. Also, there was a negative correlation between corpus callosum volume and smoking duration. The change of white matter volume (e.g., corpus callosum) might be a primary factor for characterizing the effects of smoking.

Neuroimaging of children following prenatal drug exposure

Recent advances in MR-based brain imaging methods have provided unprecedented capabilities to visualize the brain. Application of these methods has allowed identification of brain structures and patterns of functional activation altered in offspring of mothers who used licit (e.g., alcohol and tobacco) and illicit (e.g., cocaine, methamphetamine, and marijuana) drugs during pregnancy. Here we review that literature, which though somewhat limited by the complexities of separating the specific effects of each drug from other confounding variables, points to sets of interconnected brain structures as being altered following prenatal exposure to drugs of abuse. In particular, dopamine-rich cortical (e.g., frontal cortex) and subcortical (e.g., basal ganglia) fetal brain structures show evidence of vulnerability to intrauterine drug exposure suggesting that during brain development drugs of abuse share a specific profile of developmental neurotoxicity. Such brain malformations may shed light on mechanisms underlying prenatal drug-induced brain injury, may serve as bio-markers of significant intrauterine drug exposure, and may additionally be predictors of subsequent neuro-developmental compromise. Wider clinical use of these research-based non-invasive methods will allow for improved diagnosis and allocation of therapeutic resources for affected infants, children, and young adults.

Respiratory dysfunctions induced by prenatal nicotine exposure

1. Maternal tobacco smoking is the principal risk factor associated with sudden infant death syndrome (SIDS), a leading cause of death of infants under 1 year of age. Victims of SIDS show a higher incidence of respiratory control abnormalities, including central apnoeas, delayed arousal responses and diminished ventilatory chemoreflexes. 2. Nicotine is likely the link between maternal tobacco smoking and SIDS. Prenatal nicotine exposure can alter the breathing pattern and can reduce hypoxia- and hypercarbia-induced ventilatory chemoreflexes. In vitro approaches have revealed that prenatal nicotine exposure impairs central chemosensitivity, switching the cholinergic contribution from a muscarinic to a nicotinic receptor-based drive. In addition, serotonergic, noradrenergic, GABAergic, glycinergic and glutamatergic, among others, are affected by prenatal nicotine. 3. Here we propose that prenatal nicotine affects the respiratory network through two main processes: (i) reorganization of neurotransmitter systems; and (ii) remodelling of neural circuits. These changes make breathing more vulnerable to fail in early postnatal life, which could be related to the pathogenesis of SIDS.

Maternal cigarette smoking during pregnancy and cognitive performance in adolescence

BACKGROUND

The incidence of cigarette smoking during pregnancy remains high. Maternal smoking during pregnancy is known to be associated with cognitive and behavioural sequelae in childhood and adolescence. We assessed the relationship between maternal cigarette smoking during pregnancy and cognitive abilities in adolescent offspring (n = 503, 12- to 18-years old) using an extensive 6-h battery of tests.

METHODS

Non-exposed adolescents (controls) were matched to exposed adolescents (cases) by maternal education and school attended. Cognitive abilities were evaluated using a neuropsychological battery consisting of 33 tasks measuring verbal abilities, visuo-spatial skills, verbal and visual memory, processing speed, resistance to interference and motor dexterity.

RESULTS

We found no differences between cases and controls in any of the cognitive domains whether potential confounders were included in the model or not. In addition to maternal smoking during pregnancy, we also evaluated the effect of sex and age on the various cognitive abilities in this large adolescent sample and found that most of the abilities continue to improve during adolescence to the same extent in girls and boys, with several age-independent sex differences.

CONCLUSIONS

We found no effect of maternal cigarette smoking during pregnancy on cognitive abilities of the adolescent offspring when matching cases and controls by maternal education, the most common confounder of maternal cigarette smoking during pregnancy.