Environmental tobacco smoke exposure and brain development: The case of attention deficit/hyperactivity disorder

Metals, nonmetals and metalloids in cigarette smoke as hazardous compounds for human health

Cigarette smoke contains many chemicals that are harmful to both smokers and non-smokers. Breathing just a little cigarette smoke can be harmful. There are >7000 chemicals in cigarette smoke, at least 250 are known to be harmful and many of them can cause cancer. Currently, many studies reported the types of harmful organic compounds in cigarette smoke; instead, there are almost no works that describe the presence of inorganic compounds. In this work, a cost-effective self-made passive sampler (SMPS) was tested as a tool to collect different types of particulate matter (PM) from cigarette smoke containing metals as hazardous compounds (HCs). To determine the nature of the metals, nonmetals and metalloids as HCs, a direct qualitative analysis of the particulate matter (PM) was conducted without developing any special sample preparation procedure. For that, non-invasive elemental (Scanning Electron Microscope coupled to Energy Dispersive X-ray Spectrometry) and molecular (Raman microscopy) micro-spectroscopic techniques were used. Thanks to this methodology, it was possible to determine in deposited PM, the presence of metals such as Fe, Cr, Ni, Ti, Co, Sn, Zn, Ba, Al, Cu, Zr, Ce, Bi, etc. most of them as oxides but also embedded in different clusters with sulfates, aluminosilicates, even phosphates.

Is secondhand smoke associated with mental health issues? A narrative review of the evidence and policy implications

Secondhand smoke (SHS) is a well-established cause of lung cancer, respiratory disease, heart disease and developmental issues in children, with an overwhelming evidence base spanning over four decades. In this narrative review, we describe studies which have also linked self-reported or cotinine-assessed SHS exposure in the home, workplace and other settings to mental health disorders including depression, suicide, anxiety, and psychological distress in children and adults, sleeping disorders, Attention Deficit Hyperactivity Disorder and behavioural issues in children, and dementia in older adults. In general, evidence indicates that SHS exposure is associated with these disorders in a dose-response manner, with higher odds reported in people who are exposed to SHS at high levels, frequently, and in the home environment. Most studies so far are cross-sectional albeit in large, nationally representative samples from various countries with a smaller number of longitudinal studies. More research is needed in this area to determine whether SHS is a direct cause of adverse mental health outcomes, and whether creating smokefree environments leads to improved mental wellbeing. In particular, more research is needed on the impact of smokefree home environments, an area which has received relatively little focus in smokefree interventions which generally target public places.

Epigenetic and Long-Term Effects of Nicotine on Biology, Behavior, and Health

Tobacco and nicotine use are associated with disease susceptibility and progression. Health challenges associated with nicotine and smoking include developmental delays, addiction, mental health and behavioral changes, lung disease, cardiovascular disease, endocrine disorders, diabetes, immune system changes, and cancer. Increasing evidence suggests that nicotine-associated epigenetic changes may mediate or moderate the development and progression of a myriad of negative health outcomes. In addition, nicotine exposure may confer increased lifelong susceptibility to disease and mental health challenges through alteration of epigenetic signaling. This review examines the relationship between nicotine exposure (and smoking), epigenetic changes, and maladaptive outcomes that include developmental disorders, addiction, mental health challenges, pulmonary disease, cardiovascular disease, endocrine disorders, diabetes, immune system changes, and cancer. Overall, findings support the contention that nicotine (or smoking) associated altered epigenetic signaling is a contributing factor to disease and health challenges.

Nicotine on the developing brain

Developmental periods such as gestation and adolescence have enhanced plasticity leaving the brain vulnerable to harmful effects from nicotine use. Proper brain maturation and circuit organization is critical for normal physiological and behavioral outcomes. Although cigarette smoking has declined in popularity, noncombustible nicotine products are readily used. The misperceived safety of these alternatives lead to widespread use among vulnerable populations such as pregnant women and adolescents. Nicotine exposure during these sensitive developmental windows is detrimental to cardiorespiratory function, learning and memory, executive function, and reward related circuitry. In this review, we will discuss clinical and preclinical evidence of the adverse alterations in the brain and behavior following nicotine exposure. Time-dependent nicotine-induced changes in reward related brain regions and drug reward behaviors will be discussed and highlight unique sensitivities within a developmental period. We will also review long lasting effects of developmental exposure persisting into adulthood, along with permanent epigenetic changes in the genome which can be passed to future generations. Taken together, it is critical to evaluate the consequences of nicotine exposure during these vulnerable developmental windows due to its direct impact on cognition, potential trajectories for other substance use, and implicated mechanisms for the neurobiology of substance use disorders.

The association between attention deficit hyperactivity disorder (ADHD) and smoking experience or exposure to environmental tobacco smoke among children and adolescents

INTRODUCTION

Direct and indirect smoking exposure is highly related to mental health in children. This study aimed to identify the association between exposure to smoking or secondhand smoke (SHS) and attention deficit hyperactivity disorder (ADHD).

METHODS

We used data from the Korean National Health and Nutrition Examination Survey (KNHANES) from 2007 to 2019, including variables such as diagnosed ADHD, smoking status, SHS, and urine cotinine levels among children and adolescents. We estimated the risk of ADHD according to smoking or SHS exposure in various exposure groups using adjusted logistic or linear regression models.

RESULTS

Among 16434 participants, 133 children were diagnosed with ADHD (0.8%). Of these, 58 (43.6%) were aged <12 years and 75 (56.3%) were aged ≥12 years. Smoking was significantly associated with ADHD (crude odds ratio, OR=1.48; 95% CI: 1.14-3.26 and adjusted odds ratio, AOR=1.22; 95% CI: 1.02- 1.64). SHS exposure and ADHD were attenuated after adjustment (OR=2.42; 95% CI: 1.08-4.02; AOR=1.42; 95% CI: 0.86-2.64) in the logistic regression model. Smoking history was statistically associated with a younger age of ADHD diagnosis in the linear regression model.

CONCLUSIONS

Smoking and the amount of smoking among children and adolescents was associated with ADHD.

Quitting Smoking before and after Pregnancy: Study Methods and Baseline Data from a Prospective Cohort Study

Smoking during pregnancy and postpartum remains an important public health problem. No known prior study has prospectively examined mutual changes in risk factors and women's smoking trajectory across pregnancy and postpartum. The objective of this study was to report methods used to implement a prospective cohort (Msgs4Moms), present participant baseline characteristics, and compare our sample characteristics to pregnant women from national birth record data. The cohort study was designed to investigate smoking patterns, variables related to tobacco use and abstinence, and tobacco treatment quality across pregnancy through 1-year postpartum. Current smokers or recent quitters were recruited from obstetrics clinics. Analyses included Chi-square and independent sample t-tests using Cohen's d. A total of 62 participants (41 smokers and 21 quitters) were enrolled. Participants were Black (45.2%), White (35.5%), and multiracial (19.3%); 46.8% had post-secondary education; and most were Medicaid-insured (64.5%). Compared with quitters, fewer smokers were employed (65.9 vs 90.5%, Cohen's d = 0.88) and more reported financial strain (61.1% vs 28.6%; Cohen's d = 0.75). Women who continue to smoke during pregnancy cope with multiple social determinants of health. Longitudinal data from this cohort provide intensive data to identify treatment gaps, critical time points, and potential psychosocial variables warranting intervention.

Health Effects of Tobacco at the Global, Regional, and National Levels: Results From the 2019 Global Burden of Disease Study

INTRODUCTION

The purpose was to quantify the health effects of tobacco using data from the 2019 Global Burden of Disease study.

AIMS AND METHODS

We collected detailed information on tobacco consumption overall as well as its individual aspects (smoking, secondhand smoke, and chewing tobacco) for the deaths and disability-adjusted life years (DALYs) for all-cause disease, cardiovascular disease, neoplasms, and chronic respiratory diseases, and their age-standardized rates (ASRs).

RESULTS

Tobacco was responsible for 8.71 million deaths and 229.77 million DALYs globally in 2019. The ASRs of all tobacco-related deaths and DALYs declined from 1990 to 2019, to 108.55 deaths per 100 000 population and 2791.04 DALYs per 100 000 population in 2019. During any year the ASRs of all tobacco-related deaths and DALYs were higher in males than in females. The ASRs of all tobacco-related deaths and DALYs were highest in countries with a low-middle sociodemographic index (SDI) and lowest in high-SDI countries in 2019. Cardiovascular disease, neoplasms, and chronic respiratory diseases were the three leading causes of tobacco-related mortality.

CONCLUSIONS

Although the ASRs of deaths and DALYs related to tobacco have declined, the absolute number remain high. Tobacco control policies need to be strengthened further in order to reduce the heavy health burden of tobacco.

IMPLICATIONS

This study provides a detailed description on the health effects of tobacco, including maps of the current global burden of tobacco-related disease. Although the ASRs of tobacco-related deaths and DALYs have declined, the absolute numbers remain high-tobacco was responsible for 8.71 million deaths and 229.77 million DALYs globally in 2019. The findings may have implications for tobacco control. Countries where progress has been slower in reducing tobacco-related disease burden should study and consider implementing policies and strategies that have been applied in countries like Singapore which show the greatest declines for recent decades.

Nicotine and the developing brain: Insights from preclinical models

Use of tobacco products during pregnancy is associated with increased risk for neurodevelopmental disorders in the offspring. Preclinical models of developmental nicotine exposure have offered valuable insights into the neurobiology of nicotine's effects on the developing brain and demonstrated lasting effects of developmental nicotine exposure on brain structure, neurotransmitter signaling and behavior. These models have facilitated discovery of novel compounds as candidate treatments for attention deficit hyperactivity disorder, a neurodevelopmental disorder associated with prenatal nicotine exposure. Using these models the significance of heritability of behavioral phenotypes from the nicotine-exposed pregnant female or adult male to multiple generations of descendants has been demonstrated. Finally, research using the preclinical models has demonstrated synergistic interactions between developmental nicotine exposure and repetitive mild traumatic brain injury that contribute to "worse" outcomes from the injury in individuals with attention deficit hyperactivity disorder associated with developmental nicotine exposure.

Effects of Prenatal Nicotine, THC, or Co-Exposure on Cognitive Behaviors in Adolescent Male and Female Rats

INTRODUCTION

Although there has been a decrease in the prevalence of tobacco smoking, exposure to nicotine during pregnancy remains a substantial problem worldwide. Further, given the recent escalation in e-cigarette use and legalization of cannabis, it has become essential to understand the effects of nicotine and cannabinoid co-exposure during early developmental stages.

AIMS AND METHODS

We systematically examined the effects of nicotine and/or THC prenatal exposure on cognitive behaviors in male and female offspring. Dams were exposed to nicotine vape or vehicle, and oral edible THC or vehicle, throughout pregnancy. Adolescent offspring were then tested in the prepulse inhibition test, novel object recognition task, and novelty suppressed feeding task.

RESULTS

At birth, pups from mothers exposed to nicotine vape or oral THC exhibited reduced body weight, compared to control pups. Prenatal nicotine vape exposure resulted in a decreased baseline startle reactivity in adolescent male and female rats, and in females, enhanced sensorimotor gating in the prepulse inhibition test. Prenatal nicotine and THC co-exposure resulted in significant deficits in the prepulse inhibition test in males. Deficits in short-term memory were also found in males prenatally exposed to THC, either alone or with nicotine co-exposure, and in females exposed to THC alone. Finally, in males, a modest increase in anxiety-associated behaviors was found with THC or nicotine exposure in the latency to approach a novel palatable food.

CONCLUSIONS

These studies demonstrate differential effects of prenatal exposure to e-cigarette nicotine vape and/or edible THC on cognitive function, with differing effects within male and female groups.

IMPLICATIONS

These studies demonstrate an impact of nicotine, THC, or co-exposure during early developmental stages in utero on behavioral outcomes in adolescence. These findings have important translational implications given the continued use of nicotine and THC containing products by pregnant women worldwide, which can be applied to support healthcare and policy efforts restricting nicotine and THC use during pregnancy.

Animal Models of ADHD?

To describe animals that express abnormal behaviors as a model of Attention-Deficit Hyperactivity Disorder (ADHD) implies that the abnormalities are analogous to those expressed by ADHD patients. The diagnostic features of ADHD comprise inattentiveness, impulsivity, and hyperactivity and so these behaviors are fundamental for validation of any animal model of this disorder. Several experimental interventions such as neurotoxic lesion of neonatal rats with 6-hydroxydopamine (6-OHDA), genetic alterations, or selective inbreeding of rodents have produced animals that express each of these impairments to some extent. This article appraises the validity of claims that these procedures have produced a model of ADHD, which is essential if they are to be used to investigate the underlying cause(s) of ADHD and its abnormal neurobiology.

Melatonin protects cochlear hair cells from nicotine-induced injury through inhibiting apoptosis, inflammation, oxidative stress and endoplasmic reticulum stress

Hearing loss positively links with cigarette smoking. However, the involved mechanism and treatment strategies are largely unrevealed. This study aimed to investigate the damaging effect of nicotine on cochlear hair cells, reveal the underlying mechanism and evaluate the therapeutic effect of melatonin on nicotine-induced injury. The results showed that nicotine induced cytotoxicity of House Ear Institute-Organ of Corti 1 (HEI-OC1) cochlear hair cells in a dose-dependent manner (0, 2.5, 5, 10, 20, 40 and 80 μM). Functional investigations showed that nicotine (10 μM) stimulation dramatically promoted apoptosis, inflammatory response, oxidative stress and endoplasmic reticulum stress in HEI-OC1 cells. Moreover, melatonin treatment dose-dependently alleviated the nicotine-induced cytotoxicity in HEI-OC1 cells (0, 10 25, 50 and 100 μM). Further investigation showed that melatonin (100 μM) effectively attenuated the nicotine-induced apoptosis, inflammation, oxidative stress and endoplasmic reticulum stress in HEI-OC1 cells. Collectively, we demonstrated that nicotine induced apoptosis, inflammation, oxidative stress and endoplasmic reticulum stress of cochlear hair cells in an in vitro cell model. Melatonin showed protective effect on these aspects, suggesting that melatonin may be a potential agent for treating smoking-induced hearing loss.

Effects of Developmental Nicotine Exposure on Frontal Cortical GABA-to-Non-GABA Neuron Ratio and Novelty-Seeking Behavior

Cigarette smoking during pregnancy is a major public health concern, resulting in detrimental health effects in the mother and her offspring. The adverse behavioral consequences for children include increased risk for attention deficit hyperactivity disorder, working memory deficits, epilepsy, novelty-seeking, and risk-taking behaviors. Some of these behavioral conditions are consistent with an imbalance in frontal cortical excitatory (glutamate) and inhibitory (GABA) neurotransmitter signaling. We used a GAD67-GFP knock-in mouse model to examine if developmental nicotine exposure alters frontal cortical GABA neuron numbers, GABA-to-non-GABA neuron ratio and behavioral phenotypes. Female mice were exposed to nicotine (100 or 200 μg/mL) in drinking water beginning 3 weeks prior to breeding and until 3 weeks postpartum. Male and female offspring were examined beginning at 60 days of age. The nicotine exposure produced dose-dependent decreases in GABA-to-non-GABA neuron ratios in the prefrontal and medial prefrontal cortices without perturbing the intrinsic differences in cortical thickness and laminar distribution of GABA or non-GABA neurons between these regions. A significant increase in exploratory behavior and a shift toward "approach" in the approach-avoidance paradigm were also observed. Thus, developmental nicotine exposure shifts the cortical excitation-inhibition balance toward excitation and produces behavioral changes consistent with novelty-seeking behavior.

Effects of Chronic Secondhand Smoke (SHS) Exposure on Cognitive Performance and Metabolic Pathways in the Hippocampus of Wild-Type and Human Tau Mice

BACKGROUND

Exposure to secondhand smoke (SHS) is a risk factor for developing sporadic forms of sporadic dementia. A human tau (htau) mouse model is available that exhibits age-dependent tau dysregulation, neurofibrillary tangles, neuronal loss, neuroinflammation, and oxidative stress starting at an early age (3-4 months) and in which tau dysregulation and neuronal loss correlate with synaptic dysfunction and cognitive decline.

OBJECTIVE

The goal of this study was to assess the effects of chronic SHS exposure (10 months' exposure to ∼30 mg/m3) on behavioral and cognitive function, metabolism, and neuropathology in mice.

METHODS

Wild-type (WT) and htau female and male mice were exposed to SHS (90% side stream, 10% main stream) using the SCIREQ® inExpose™ system or air control for 168 min per day, for 312 d, 7 d per week. The exposures continued during the days of behavioral and cognitive testing. In addition to behavioral and cognitive performance and neuropathology, the lungs of mice were examined for pathology and alterations in gene expression.

RESULTS

Mice exposed to chronic SHS exposure showed the following genotype-dependent responses: a) lower body weights in WT, but not htau, mice; b) less spontaneous alternation in WT, but not htau, mice in the Y maze; c) faster swim speeds of WT, but not htau, mice in the water maze; d) lower activity levels of WT and htau mice in the open field; e) lower expression of brain PHF1, TTCM1, IGF1β, and HSP90 protein levels in WT male, but not female, mice; and f) more profound effects on hippocampal metabolic pathways in WT male than female mice and more profound effects in WT than htau mice.

DISCUSSION

The brain of WT mice, in particular WT male mice, might be especially susceptible to the effects of chronic SHS exposure. In WT males, independent pathways involving ascorbate, flavin adenine dinucleotide, or palmitoleic acid might contribute to the hippocampal injury following chronic SHS exposure. https://doi.org/10.1289/EHP8428.

Repetitive Mild Traumatic Brain Injury in a Perinatal Nicotine Exposure Mouse Model of Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) increases the risk for concussion or mild traumatic brain injury (mTBI). At the same time, recommendations for the management of ADHD include participation in sports and other organized physical activities, including those that carry an increased risk of mTBI. Very little work has been done to determine the extent to which untreated ADHD adversely impacts behavioral outcomes of repeated mild concussions. Here, we used a perinatal nicotine exposure (PNE) mouse model of ADHD combined with a closed-head, repetitive mTBI model. The PNE mouse model carries significant construct, face, and predictive validity as a preclinical model of ADHD. Two-month-old PNE and control mice were subjected to closed-head repetitive mTBI or sham procedure once daily for 5 days. Object-based attention, novel object recognition memory, spatial working memory, and depression-like behavior were analyzed 1 day and 2 weeks following repeated mTBI. Consistent with our previous reports, mice in the PNE group showed significant deficits in object-based attention and working memory prior to mTBI. These deficits persisted following the repeated mTBI. Repeated mTBI produced a transient attention deficit in the control group but did not exacerbate the attention deficit that is characteristic of the PNE group. Although neither PNE nor repetitive mTBI alone influenced immobility in the tail suspension test, when PNE mice were subjected to mTBI, there was a transient increase in this measurement suggesting a synergistic effect of ADHD and mTBI on depression-like behavior. Thus, our data using the PNE mouse model suggest that ADHD may be a risk factor for transient depression following repeated mTBI and that repeated mTBI may be a risk factor for transient attention deficit.

Exposure to Secondhand Smoke in Children is Associated with a Thinner Retinal Nerve Fiber Layer: The Hong Kong Children Eye Study

PURPOSE

We sought to assess the effects of exposure to secondhand smoke (SHS) on peripapillary retinal nerve fiber layer (p-RNFL) thickness in children.

DESIGN

Cross-sectional study.

METHODS

Children 6-8 years of age were consecutively recruited from the population-based Hong Kong Children Eye Study. All participants received comprehensive ophthalmic examinations and p-RNFL thickness was measured by spectral-domain optical coherence tomography. SHS data were derived from a validated questionnaire. Associations between p-RNFL thickness and SHS exposure status, number of smokers in the family, and quantity of smoking in the family were determined by multivariate linear regression after adjusting for potential confounders.

RESULTS

Among the Hong Kong Children Eye Study cohort (n = 3,103), approximately one-third of children were exposed to SHS (35.4%, n = 1,097). Compared to those without exposure to SHS, children exposed to SHS had similar age (P = .83), gender (P = .17), body mass index (P = .44), birth weight (P = .23), and axial length (P = .34), but had lower family income (P < .001) and lower parental education level (P < .001). After adjusting for all the above factors, exposure to SHS was associated with a thinner global p-RNFL by 4.4 μm (P < .001). Reduced p-RNFL was also associated with increased numbers of smokers in the family (β = -3.40, P < .001) and increased quantity of SHS (β = -0.22, P < .001).

CONCLUSIONS

Exposure to SHS in children was associated with a thinner p-RNFL. A thinner p-RNFL may increase the risk of irreversible visual impairment in the future. Our results provide evidence to recommend that children avoid exposure to SHS.

Association between postnatal second-hand smoke exposure and ADHD in children: a systematic review and meta-analysis

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder which is caused by the interplay of genetic and environmental risk factors such as second-hand smoke (SHS). The association between postnatal exposure to SHS and ADHD risk in children was still inconclusive. We performed a systematic review and meta-analysis to explore the definite association. We searched for relevant studies from PubMed, Embase, Ovid, and Web of Science databases up to January 2020. We used random effect models to calculate pooled odds ratio (OR) with 95% confidence interval (CI). Subgroup analyses and sensitive analyses were also performed to solve the heterogeneity. According to our inclusion criteria, 9 studies including 6 cross-sectional studies, 2 cohort studies, and 1 case-control study were included in the final analysis. Postnatal exposure to SHS increased the risk of ADHD in children (OR: 1.60; 95% CI: 1.37-1.87). Children who exposed to SHS were found a slight risk for conduct problems (OR: 1.33, 95% CI: 1.00-1.77). Among the studies which used cotinine as a biomarker for SHS exposure, a lower pooled OR (OR = 1.16, 95%CI = 1.01, 1.33) was observed between cotinine and ADHD in children. Our meta-analysis results suggested that SHS exposure may be a risk factor for ADHD. We also found that SHS exposure may be associated with some adverse behavioral outcomes. More prospective studies should be conducted to confirm the relationship between SHS exposure and ADHD in children.

Frontal Cortical Monoamine Release, Attention, and Working Memory in a Perinatal Nicotine Exposure Mouse Model Following Kappa Opioid Receptor Antagonism

Perinatal nicotine exposure (PNE) produces frontal cortical hypo-dopaminergic state and attention and working memory deficits consistent with neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD). Methylphenidate alleviates ADHD symptoms by increasing extracellular dopamine and noradrenaline. Kappa opioid receptor (KOR) antagonism may be another mechanism to achieve the same results because KOR activation inhibits frontal cortical dopamine release. We administered the selective KOR antagonist norbinaltorphimine (norBNI) (20 mg/kg; intraperitoneal) or methylphenidate (0.75 mg/kg; intraperitoneal) to PNE mouse model and examined frontal cortical monoamine release, attention, and working memory. Both compounds increased dopamine and noradrenaline release but neither influenced serotonin release. Both compounds improved object-based attention and working memory in the PNE group, with norBNI's effects evident at 2.5 h and 5.5 h but absent at 24 h. Methylphenidate's effects were evident at 0.5 h but not at 2.5 h. norBNI's effects temporally coincided with frontal cortical c-Jun N-terminal kinase phosphorylation. norBNI did not alter tissue dopamine content in the nucleus accumbens, offering preliminary support for lack of reinforcement.

The association between maternal exposure to secondhand smoke during pregnancy and their children's cerebral palsy, Shandong, China

INTRODUCTION

Tobacco use poses a threat to the health of pregnant women and their children. Our study assessed the association between maternal exposure to secondhand smoke (SHS) during pregnancy and children's cerebral palsy (CP) in Shandong, China.

METHODS

In our observational study, 5067 mother-child pairs were included from Shandong Province, China. Mothers filled in questionnaires about exposure to SHS during pregnancy. Statistical analysis and logistic regression models were built in R program to estimate the association in adjusted odds ratio (AOR) between SHS exposure during pregnancy and risk of children's CP, after adjustment for potential confounders including delivery mode and baby's birthweight.

RESULTS

Exposure to SHS was noted among 3663 (72.3%) of the 5067 non-smoking mothers during their pregnancy. Of the 239 CP children within the study, 192 (80.3%) were exposed to SHS during pregnancy. Children born to mothers exposed to SHS during pregnancy had a higher risk of CP (AOR=1.44; 95% CI: 1.02-2.04) than those born to non-exposed mothers, the risk increased by exposure time in the logistic regression model. The association between SHS exposure during pregnancy and CP children remained significant when adjusting for delivery mode and infant's birthweight due to their significant association with CP, with an AOR of 1.46 (95% CI: 1.13-1.91) for 1-4 days/week and 1.63 (95% CI: 1.22-2.01) for 5-7 days/week exposure to SHS.

CONCLUSIONS

Our study suggests that maternal exposure to secondhand smoke during pregnancy is associated with children's CP. Future preventive interventions of CP should include strategies that target the antenatal women who are exposed to SHS.

Maternal Smoking During Pregnancy and ADHD: Results From a Systematic Review and Meta-Analysis of Prospective Cohort Studies

Objective: Findings on maternal smoking during pregnancy and ADHD risk in children are inconsistent. A meta-analysis was performed to summarize effects of exposure to maternal smoking during pregnancy on ADHD risk in children. Method: We conducted a systematic literature search to select articles up to June 2016. Only prospective cohort studies were included. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated. Results: Pooled RR estimates based on 12 cohort studies including 17,304 pregnant women suggested that maternal smoking during pregnancy was associated with an increased risk of ADHD (pooled RR = 1.58, 95% CI = [1.33, 1.88]). Conclusion: Results from this study indicate that maternal smoking during pregnancy is related to an increased risk of ADHD in children. There is an urgent need to increase maternal awareness of smoking risk and quitting smoking to mitigate the ADHD risk in children.

Environmental Tobacco Smoke and Educational Self-Regulation and Achievement in First Grade High School Students

Environmental tobacco smoke, containing many toxic gases, suggests inevitable contact of humans with the damaging factors of cigarettes. On average, approximately 40% of children, 35% of women and 32% of men worldwide are exposed to environmental tobacco smoke. This study aims at investigating the relationship between environmental tobacco smoke in adolescents and their educational self-regulation and achievement. In this study, 770 students aged between 13 and 15 were selected and studied using the multistage sampling method. The tools used in this study consisted of four questionnaires, demographic characteristics, environmental tobacco smoke, educational self-regulation, and educational achievement. The validity and reliability of tools have been approved, and the data were analyzed using SPSS v22. The results indicated a significant inverse relationship between environmental tobacco smoke and students' educational self-regulation and achievement (p-value > 0.001). Given the relationship between exposure to environmental tobacco smoke and educational self-regulation and achievement, it is essential to keep children away from tobacco smoke. Family health and education policy-makers are recommended to design and operate fundamental schemes in order to deal with environmental tobacco smoke.

Transgenerational transmission of behavioral phenotypes produced by exposure of male mice to saccharin and nicotine

The use of non-nutritive sweeteners such as saccharin is widely prevalent. Although saccharin is considered safe for human consumption, it produces behavioral changes in experimental animals. We report that saccharin’s behavioral effects are much more pervasive than currently recognized. In a mouse model, saccharin exposure produced motor impulsivity not only in the saccharin-exposed males but also in their offspring. In addition, the offspring showed locomotor hyperactivity and working memory deficit not observed in fathers. Spermatazoal DNA was hypermethylated in the saccharin-exposed fathers, especially at dopamine receptor promoter regions, suggesting that epigenetic modification of germ cell DNA may mediate transgenerational transmission of behavioral phenotypes. Dopamine’s role in hyperactivity was further highlighted by the finding that the stimulant drug methylphenidate mitigated the hyperactivity. Nicotine is another substance that is widely used. Its use via smokeless tobacco products, some of which contain saccharin, is on the rise contributing to concerns about adverse outcomes of co-exposure to saccharin and nicotine. We found that co-exposure of male mice to saccharin and nicotine produced significant behavioral impairment in their offspring. Thus, our data point to potential adverse neurobehavioral consequences of exposure to saccharin alone or saccharin and nicotine for the exposed individuals and their descendants.

Description of Maternal Smoking Status Before and After Pregnancy: A Longitudinal, Community-Based Cohort Study

Background

Maternal smoking during pregnancy is a major risk for adverse perinatal outcomes, as well as children’s health status. Thus, it is important to describe maternal smoking status during pregnancy and child-rearing to devise better intervention strategies. However, there have been no longitudinal studies to describe the status. Thus, in this study, we aimed to describe maternal smoking status during pregnancy and child-rearing based on population-based maternal and child health information. Moreover, we explored the factors associated with maternal smoking relapse after delivery.

Methods

We performed a survey of 1,220 mothers in a Japanese rural area who responded to a questionnaire upon registration of their pregnancies. When their children received health checkups at 4, 18, and 36 months of age, maternal smoking status was also surveyed. We then performed multiple logistic regression analysis to explore factors associated with maternal smoking relapse after delivery.

Results

Ultimately, the total number of mothers with data available for longitudinal analysis was 727 (59.6%). At the time of pregnancy registration, there were 74 current smokers (10.2%) and 176 former smokers (24.2%). Among them, 59 (33.5%) relapsed after delivery. Under 28 years of maternal age at pregnancy registration (OR 2.6; 95% CI, 1.2–5.4) was associated with maternal smoking relapse after delivery.

Conclusions

Longitudinal analyses showed that about 60% of mothers who smoked before and after delivery failed smoking cessation. In addition, younger mothers were significantly likely to relapse smoking after delivery.

Magnitude and Chronicity of Environmental Smoke Exposure Across Infancy and Early Childhood in a Sample of Low-Income Children

INTRODUCTION

Infants and young children may be at an increased risk for second- and thirdhand exposure to tobacco smoke because of increased respiration rate and exposure to surface residue. However, relatively fewer studies have examined biomarkers of exposure (cotinine) in children under age 4 years. This study examines the magnitude and chronicity of exposure across early childhood among children from low-income families in order to better characterize contextual risk factors associated with exposure.

METHODS

A total of 1292 families were recruited in six nonurban counties of Pennsylvania and North Carolina. Cotinine was assayed from infant saliva at 6, 15, 24, and 48 months of age (N = 1218), and categorized as low (≤0.45 ng/mL), moderate (0.46-12 ng/mL), or high (≥12 ng/mL) at each time point. Categories were highly correlated across time. Latent class analysis was used to summarize patterns of exposure categories across time.

RESULTS

Magnitude of exposure in this sample was high, with approximately 12% of infants registering cotinine values at least 12 ng/mL, consistent with active smoking in adults. Greater exposure was associated with lower income, less education, more residential instability, and more instability in adult occupants in the home, whereas time spent in center-based day care was associated with lower exposure.

CONCLUSIONS

Young children from low-income, nonurban communities appear to bear a higher burden of secondhand smoke exposure than previous studies have reported. Results contribute to understanding populations at greater risk, as well as specific, potentially malleable, environmental factors that may be examined as direct contributors to exposure.

IMPLICATIONS

Results suggest that infants from low-income, nonurban families have higher risk for environmental smoke exposure than data from nationally representative samples. Predictors of exposure offer insights into specific factors that may be targeted for risk reduction efforts, specifically conditions of children's physical space. In addition to considering the increases in risk when an adult smoker lives in a child's home, families should also attend to the possible risk embedded within the home itself, such as residual smoke from previous occupants. For high-risk children, day care appears to mitigate the magnitude of exposure by providing extended time in a smoke-free environment.

Paternal factors in neurodevelopmental toxicology: THC exposure of male rats causes long-lasting neurobehavioral effects in their offspring

The potential health risks of cannabis are of growing concern, including effects on reproduction and development. Extensive research has investigated risks associated with maternal exposure to THC during gestation and its impacts on the development of offspring, but little research has been done regarding paternal THC exposure effects prior to conception. We have previously found that paternal THC exposure in rats causes changes in sperm methylation. In an initial study we also showed that a 12-day paternal THC exposure prior to conception alters locomotor activity and impairs cognitive function of their offspring. This study investigated the cross-generational effects of chronic paternal THC exposure in rats (0, 2, or 4 mg/kg/day SC for 28 days) prior to mating with drug naïve females. The offspring of THC-exposed male rats had significant alterations in locomotor activity and cognitive function. Specifically, during adolescence there was significant locomotor hyperactivity in the offspring of males exposed to 2 mg/kg/day of THC. During the novel object recognition task, the controls maintained their relative preference for the novel object across the duration of the ten-min session while the rats whose fathers received THC (2 mg/kg/day) showed a significantly greater drop-off in interest in the novel object during the second half of the session. Learning in the radial-arm maze was significantly delayed in the offspring of males exposed to 4 mg/kg/day of THC. This study shows that premating chronic paternal THC exposure at multiple dose regimens can cause long-lasting detrimental behavioral effects in their offspring, including abnormal locomotor activity and impaired cognitive function. Future studies should investigate the underlying mechanisms driving these aberrant developmental outcomes and seek to identify possible treatments of alleviation in the presence of paternal THC exposure.

Environmental Tobacco Smoke During the Early Postnatal Period of Mice Interferes With Brain 18 F-FDG Uptake From Infancy to Early Adulthood - A Longitudinal Study

Exposure to environmental tobacco smoke (ETS) is associated with high morbidity and mortality, mainly in childhood. Our aim was to evaluate the effects of postnatal ETS exposure in the brain 2-deoxy-2-[¹⁸F]-fluoro-D-glucose (¹⁸F-FDG) uptake of mice by positron emission tomography (PET) neuroimaging in a longitudinal study. C57BL/6J mice were exposed to ETS that was generated from 3R4F cigarettes from postnatal day 3 (P3) to P14. PET analyses were performed in male and female mice during infancy (P15), adolescence (P35), and adulthood (P65). We observed that ETS exposure decreased ¹⁸F-FDG uptake in the whole brain, both left and right hemispheres, and frontal cortex in both male and female infant mice, while female infant mice exposed to ETS showed decreased ¹⁸F-FDG uptake in the cerebellum. In addition, all mice showed reduced ¹⁸F-FDG uptake in infancy, compared to adulthood in all analyzed VOIs. In adulthood, ETS exposure during the early postnatal period decreased brain ¹⁸F-FDG uptake in adult male mice in the cortex, striatum, hippocampus, cingulate cortex, and thalamus when compared to control group. ETS induced an increase in ¹⁸F-FDG uptake in adult female mice when compared to control group in the brainstem and cingulate cortex. Moreover, male ETS-exposed animals showed decreased ¹⁸F-FDG uptake when compared to female ETS-exposed in the whole brain, brainstem, cortex, left amygdala, striatum, hippocampus, cingulate cortex, basal forebrain and septum, thalamus, hypothalamus, and midbrain. The present study shows that several brain regions are vulnerable to ETS exposure during the early postnatal period and these effects on ¹⁸F-FDG uptake are observed even a long time after the last exposure. This study corroborates our previous findings, strengthening the idea that exposure to tobacco smoke in a critical period interferes with brain development of mice from late infancy to early adulthood.

Particulate Matter Exposure and Attention-Deficit/Hyperactivity Disorder in Children: A Systematic Review of Epidemiological Studies

Attention-deficit/hyperactivity disorder (ADHD) is the most common cognitive and behavioural disorder affecting children, with a worldwide-pooled prevalence of around 5%. Exposure to particulate matter (PM) air pollution is suspected to be associated with autism spectrum disorders and recent studies have investigated the relationship between PM exposure and ADHD. In the absence of any synthesis of the relevant literature on this topic, this systematic review of epidemiological studies aimed to investigate the relationship between the exposure of children to PM and ADHD and identify gaps in our current knowledge. In December 2018, we searched the PubMed and EMBASE databases. We only included epidemiological studies carried out on children without any age limit, measuring PM exposure and health outcomes related to ADHD. We assessed the quality of the articles and the risk of bias for each included article using the Newcastle-Ottawa Scale and the Office of Health Assessment and Translation (OHAT) approach, respectively. The keyword search yielded 774 results. Twelve studies with a total number of 181,144 children met our inclusion criteria, of which 10 were prospective cohort studies and 2 were cross-sectional studies. We subsequently classified the selected articles as high or good quality studies. A total of 9 out of the 12 studies reported a positive association between PM exposure to outdoor air pollution and behavioral problems related to attention. Despite these results, we found a significant degree of heterogeneity among the study designs. Furthermore, 11 studies were judged to be at a probably high risk of bias in the exposure assessment. In conclusion, we opine that further high quality studies are still needed in order to clarify the association between PM exposure and ADHD diagnosis.

Impact of Perinatal Different Intrauterine Environments on Child Growth and Development: Planning and Baseline Data for a Cohort Study

Background

Several studies have shown that exposure of the fetus and newborn to prenatal and perinatal events, respectively, may influence the health outcomes of the child throughout their life cycle.

Objective

This study aimed to increase the knowledge on the impact of different intrauterine environments on child growth and development, as we know that pregnancy and early years are a window of opportunity for health promotion and prevention interventions of diseases.

Methods

The recruitment occurred 24 to 48 hours after delivery and involved mothers and their newborns in 2 public hospitals in Porto Alegre, Brazil, from December 2011 to January 2016. The mothers-newborns dyads were allocated to 5 groups: diabetes mellitus, mothers with a clinical diagnosis of diabetes; systemic arterial hypertension (SAH), mothers with a clinical diagnosis of systematic arterial hypertensive disease during pregnancy; maternal smoking, mothers who smoked at any moment of gestation; small for gestational age (SGA), mothers with SGA newborns because of intrauterine growth restriction; and control, mothers without the clinical characteristics previously mentioned. Several protocols and anthropometric measurements were applied in the interviews at immediate postpartum and 7 and 15 days and 1, 3, and 6 months after birth. For this study, we analyzed only data collected during postpartum interviews. The statistical analyses were performed using Pearson chi-square test, Mann-Whitney test, or Kruskal-Wallis test with Dunn post hoc. The significance level was set at 5%. The Hospital Ethics and Research Committees approved the study.

Results

Of the 485 eligible mothers-newborns dyads, 400 agreed to participate (82.5%, 400/485). As expected, newborns from the SGA group had significantly lower birth weight, smaller stature, and lower cephalic perimeter (P<.001). This group also had the highest percentage of primiparous women in comparison with other groups (P=.005) except for control. Mothers from the SAH group had the highest mean age, the highest percentage of cesarean sections, and presented greater gestational weight gain.

Conclusions

In this study, we describe the planning and structure for the systematic follow-up of mother-newborn dyads in the first 6 months after birth, considering the important demographic and epidemiological transition scenario in Brazil. The results of this prospective longitudinal study may provide a better understanding of the causal mechanisms involved in health and life course disease related to different adverse intrauterine environments.

Paternal THC exposure in rats causes long-lasting neurobehavioral effects in the offspring

Developmental neurotoxicity of a wide variety of toxicants mediated via maternal exposure during gestation is very well established. In contrast, the impacts of paternal toxicant exposure on offspring neurobehavioral function are much less well studied. A vector for paternal toxicant exposure on development of his offspring has been identified. Sperm DNA can be imprinted by chemical exposures of the father. Most but not all of the epigenetic marks in sperm are reprogrammed after fertilization. The persisting epigenetic marks can lead to abnormal genetic expression in the offspring. We have found that paternal delta-9-tetrohydrocannabinol (THC) exposure in rats causes changes in methylation of sperm (Murphy et al., 2018). This is similar to cannabis-associated changes in sperm DNA methylation we found in human males who smoke cannabis (Murphy et al., 2018). In the current study we investigated the intergeneration effects of THC exposure of young adult male rats (0 or 2 mg/kg/day orally for 12 days) to the neurobehavioral development of their offspring. This paternal THC exposure was not found to significantly impact the clinical health of the offspring, including litter size, sex ratio, pup birth weight, survival and growth. However, it did cause a long-lasting significant impairment in attentional performance in the offspring relative to controls when they were tested in adulthood. There was also a significant increase in habituation of locomotor activity in the adult offspring of the males exposed to THC prior to mating. This study shows that premating paternal THC exposure even at a modest dose for a brief period can cause deleterious long-term behavioral effects in the offspring, notably significant impairment in an operant attention task. Further research should be conducted to determine the degree to which this type of risk is seen in humans and to investigate the mechanisms underlying these effects and possible treatments to ameliorate these long-term adverse behavioral consequences of paternal THC exposure.

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 link between parental smoking and youth externalizing behaviors: Effects of smoking, psychosocial factors, and family characteristics

This study examined the associations between parental cigarette smoking and youth externalizing behaviors (i.e., oppositional and conduct problems) both concurrently and 1 year later, and tested whether parental smoking predicted youth externalizing over and above parent psychosocial, family, and demographic characteristics linked to smoking and externalizing behaviors. Data were drawn from the Seattle Social Development Project (SSDP) and The Intergenerational Project (TIP), a prospective longitudinal study aimed toward understanding the intergenerational transmission of substance use, mental health, and risky behaviors. The current study used multilevel modeling to examine both concurrent and lagged associations from 325 families, which included parents and youth (Aged 6-19) across seven waves of data. In concurrent analyses, both parental smoking and several family characteristics independently predicted higher levels of child externalizing behaviors, even after controlling for parent age at child birth and demographic correlates of smoking. However, parental depressive symptoms reduced the association between smoking and externalizing behaviors to nonsignificance in concurrent models. In lagged analyses, only harsh parenting, low monitoring, and low parent-child bonding predicted externalizing behaviors 1 year later; parental smoking did not predict externalizing behaviors over time. Results showed that parental smoking, mental health, parenting, and family relationships all are associated with externalizing problems and constitute potential intervention targets in the short term, though poor parenting and parent-child bonding, rather than smoking, predicted externalizing behaviors over time. The robust association between concurrent parental depressive symptoms and youth conduct problems may suggest prioritizing parental mental health (e.g., via mental health screening) for improving both parent and child well-being. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Frontal Cortex Proteome Perturbation after Juvenile Rat Secondhand Smoke Exposure

Secondhand smoke remains a global concern for children's health. Epidemiological studies implicate exposure to secondhand smoke as a major risk factor for behavioral disorders, yet biological causation remains unclear. Model studies have mainly focused on secondhand smoke impacts to prenatal neurodevelopment, yet juvenile exposure represents a separate risk. Using ion mobility-enhanced data-independent mass spectrometry, the effect of juvenile secondhand smoke exposure on the prefrontal cortex, a principal part of the brain involved in behavioral control, is characterized. The produced dataset includes 800 significantly responsive proteins within the juvenile orbital frontal cortex, with 716 showing an increase in abundance. The neuroproteomic response reflects a prominent perturbation within the glutamatergic synaptic system, suggesting aberrant, disorganized excitation as observed underlying psychiatric disorders. Also disclosed are impacts to GABAergic and dopaminergic systems. Overall, the dataset provides a wealth of detail, facilitating further targeted research into the causal mechanisms underlying behavioral disorders associated with juvenile exposure to secondhand smoke and other environmental pollutants. All MS data have been deposited to the ProteomeXchange consortium with identifier PXD011744.

Early childhood exposure to secondhand smoke and behavioural problems in preschoolers

Evidence on behavioural abnormalities in children exposed to secondhand smoke is limited. This study examined the relation between infant/ toddler cotinine concentration, a biomarker of secondhand smoke exposure, and behavioural problems in preschoolers who were unexposed to maternal smoking during gestation. A prospective cohort of 301 non-smoking mothers with their young children aged ≤18 months visiting postnatal primary care clinics in Hong Kong was enrolled in 2012 and followed by telephone survey 3 years afterwards. Saliva was collected at baseline for cotinine assay. Child behavioural health at 3-year follow-up was assessed by the parent-reported Strengths and Difficulties Questionnaire (SDQ). We conducted multivariable linear regressions to compute regression coefficients (b) of SDQ scores in relation to salivary cotinine level. Mean ± SD age of children at follow-up was 3.7 ± 0.5 years and 50.8% were boys. After adjusting for age, sex, birthweight, household income, housing type, maternal education and depressive symptoms, greater cotinine concentrations during early childhood were associated with greater conduct problems (b = 0.90, 95% CI 0.03-1.76) and hyperactivity/ inattention (b = 1.12, 95% CI 0.07-2.17) at preschool age. This study corroborates previous findings on the potential role of secondhand smoke in development of child behavioural problems.

Associations between urinary cotinine and symptoms of attention deficit/hyperactivity disorder and autism spectrum disorder

BACKGROUND

The present study investigated associations between urinary cotinine levels as a biomarker of secondhand smoke exposure and symptoms of attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD).

METHODS

A total of 520 child participants (200 with ADHD, 67 with ASD, and 253 normal control subjects) were assessed using the Korean version of the ADHD rating scale (K-ARS), Autism spectrum screening questionnaire (ASSQ), and Behavioral Assessment System for Children, second edition (BASC-2). The Korean version of the computer-based continuous performance test was used to assess cognitive function. Urinary cotinine was evaluated as a biomarker of secondhand smoke exposure.

RESULTS

Urinary cotinine levels were significantly and positively associated with K-ARS score (B = 4.00, p < 0.001), ASSQ score (B = 1.71, p = 0.030), the behavioral problem subscales of the BASC-2 (B = 1.68-3.52, p < 0.001-0.045), and omission and commission errors in the continuous performance test (B = 6.21-8.42, p < 0.001-0.019). Urinary cotinine levels were also associated with the increased odds ratio of ADHD (OR = 1.55, 95% CI 1.05-2.30, p = 0.028) and ASD (OR = 1.89, 95% CI 1.12-3.21, p = 0.018).

CONCLUSION

Urinary cotinine levels were associated with lower behavioral adaptation and cognitive function and increased odds ratios of ADHD and ASD, indicating a negative effect of secondhand smoke exposure on the symptomatic manifestation of ADHD and ASD.

Nicotine exposure of male mice produces behavioral impairment in multiple generations of descendants

Use of tobacco products is injurious to health in men and women. However, tobacco use by pregnant women receives greater scrutiny because it can also compromise the health of future generations. More men smoke cigarettes than women. Yet the impact of nicotine use by men upon their descendants has not been as widely scrutinized. We exposed male C57BL/6 mice to nicotine (200 μg/mL in drinking water) for 12 wk and bred the mice with drug-naïve females to produce the F1 generation. Male and female F1 mice were bred with drug-naïve partners to produce the F2 generation. We analyzed spontaneous locomotor activity, working memory, attention, and reversal learning in male and female F1 and F2 mice. Both male and female F1 mice derived from the nicotine-exposed males showed significant increases in spontaneous locomotor activity and significant deficits in reversal learning. The male F1 mice also showed significant deficits in attention, brain monoamine content, and dopamine receptor mRNA expression. Examination of the F2 generation showed that male F2 mice derived from paternally nicotine-exposed female F1 mice had significant deficits in reversal learning. Analysis of epigenetic changes in the spermatozoa of the nicotine-exposed male founders (F0) showed significant changes in global DNA methylation and DNA methylation at promoter regions of the dopamine D2 receptor gene. Our findings show that nicotine exposure of male mice produces behavioral changes in multiple generations of descendants. Nicotine-induced changes in spermatozoal DNA methylation are a plausible mechanism for the transgenerational transmission of the phenotypes. These findings underscore the need to enlarge the current focus of research and public policy targeting nicotine exposure of pregnant mothers by a more equitable focus on nicotine exposure of the mother and the father.

Parental smoking and depression, and attention-deficit hyperactivity disorder in children and adolescents: Korean national health and nutrition examination survey 2005-2014

INTRODUCTION

We aimed to investigate the risk factors associated with attention-deficit hyperactivity disorder (ADHD) in children and adolescents using a nationally representative sample of the Korean population.

METHODS

Data from children and adolescents aged less than 18 years (n = 23 561) were obtained from the Korean National Health and Nutrition Examination Survey, 2005 to 2014. ADHD was assessed using a self-reported diagnosis of ADHD. We estimated the annual prevalence and number of Korean children and adolescents with physician-diagnosed ADHD from 2005 to 2014. We considered various risk factors including demographics, obesity, and family environment (household income, parental age, depression in adults in the household, and exposure to environmental smoke at home). The relationship between ADHD and the considered risk factors was evaluated using multiple logistic regression.

RESULTS

The annual prevalence of physician-diagnosed ADHD showed a 4-fold increase (0.35% in 2005 and 1.36% 2014) over the study period. Among ADHD patients, boys and girls constituted 78% and 22%, respectively. Total smoking amounts and depression in adults in the household were significantly associated with children's ADHD. When the analysis was limited to parental effects, only the father's smoking amount and depression were associated with the children's ADHD.

DISCUSSION

This study identified adults' smoking and depression as family environmental factors associated with children's ADHD. From a public health care perspective, this result illuminates the need for awareness programs emphasizing a parent's conditions that may influence the development of ADHD in children.

Combined early life stressors: Prenatal nicotine and maternal deprivation interact to influence affective and drug seeking behavioral phenotypes in rats

Early life stress (ELS) increases the risk for later cognitive and emotional dysfunction, and has been implicated in the etiology of multiple psychiatric disorders. We hypothesize that combined insults during gestation and infancy, critical periods of neural development, could exacerbate neuropsychiatric outcomes in later life. Thus, we investigated the effects of maternal deprivation (MD) stress alone or combined with prenatal nicotine exposure (PNE) on negative affective states, ethanol drinking, and development of mesolimbic loci that regulate depression and drug dependence. On the elevated plus maze (EPM), MD rats exhibited ∼50% increase in risk-taking behavior/decreased anxiety when compared to control, but the combined MD + PNE did not affect this specific behavior. In the open field test, however, both MD and MD + PNE groups showed 2-fold greater locomotor activity. Furthermore, whereas MD showed greater latency to fall at 40 RPM on the rotarod compared to control, the MD + PNE animals' latency to fall was significantly greater at all RPMs tested, with an approximate 15% enhancement in motor coordination overall compared to control and MD. Analyses of depressive symptomatology with the forced swim test (FST) yielded 2- and 3-fold higher immobility times in MD and MD + PNE respectively. When tested in an operant drinking paradigm to quantify the effect of treatment on 10%v/v ethanol drinking, the MD and MD + PNE groups showed heightened ethanol consumption by ∼3- and 2-fold respectively. However, the experience of PNE reduced ethanol consumption in adults relative to MD alone. To test the stressors' impact on neurons in the amygdala and ventral tegmental area (VTA), mesolimbic anatomical regions associated with mood and reward, unbiased stereological measurements were performed and revealed ∼15% increase in number and density of neurons in the amygdala for both MD and MD + PNE, and ∼13% reduction in dopaminergic-like neurons in the VTA compared to control. We report here that multiple early stressors including prenatal nicotine and MD can modulate the neuroanatomy of the amygdala and VTA. These early life stressors can interact to influence the development of depressive-like and addictive behaviors.

Attention and working memory deficits in a perinatal nicotine exposure mouse model

BACKGROUND

Cigarette smoking by pregnant women is associated with a significant increase in the risk for cognitive disorders in their children. Preclinical models confirm this risk by showing that exposure of the developing brain to nicotine produces adverse behavioral outcomes. Here we describe behavioral phenotypes resulting from perinatal nicotine exposure in a mouse model, and discuss our findings in the context of findings from previously published studies using preclinical models of developmental nicotine exposure.

METHODOLOGY/PRINCIPAL FINDINGS

Female C57Bl/6 mice received drinking water containing nicotine (100μg/ml) + saccharin (2%) starting 3 weeks prior to breeding and continuing throughout pregnancy, and until 3 weeks postpartum. Over the same period, female mice in two control groups received drinking water containing saccharin (2%) or plain drinking water. Offspring from each group were weaned at 3-weeks of age and subjected to behavioral analyses at 3 months of age. We examined spontaneous locomotor activity, anxiety-like behavior, spatial working memory, object based attention, recognition memory and impulsive-like behavior. We found significant deficits in attention and working memory only in male mice, and no significant changes in the other behavioral phenotypes in male or female mice. Exposure to saccharin alone did not produce significant changes in either sex.

CONCLUSION/SIGNIFICANCE

The perinatal nicotine exposure produced significant deficits in attention and working memory in a sex-dependent manner in that the male but not female offspring displayed these behaviors. These behavioral phenotypes are associated with attention deficit hyperactivity disorder (ADHD) and have been reported in other studies that used pre- or perinatal nicotine exposure. Therefore, we suggest that preclinical models of developmental nicotine exposure could be useful tools for modeling ADHD and related disorders.

Docosahexaenoic acid supplementation for children with attention deficit hyperactivity disorder: A comprehensive review of the evidence

Attention deficit hyperactivity disorder (ADHD) is considered the most common behavioural disorder in school-age children. ADHD is a complex and multifactorial disorder characterised by a variety of symptoms, including concentration problems, excessive motor activity and impulsivity which interferes with execution of simple school tasks. Diagnosis has been essentially subjective, since no specific laboratory tests are available. However, ADHD remains overdiagnosed, probably due to social pressures for children to be successful in school from an early age, which leads parents to seek medical support. Although therapeutic approaches for ADHD have been essentially pharmacologic, in recent years several studies were performed to investigate the role of nutrition, especially omega 3 polyunsaturated fatty acid (omega 3-PUFA), in the development and treatment of this disorder. In this review, the authors gathered the most relevant evidence regarding omega 3-PUFA, mainly docosahexaenoic acid, as coadjutant or as a single therapy, in the management of ADHD symptoms. The authors also reviewed this disorder's current medical and therapeutic features.

Antecedents of Screening Positive for Attention Deficit Hyperactivity Disorder in Ten-Year-Old Children Born Extremely Preterm

BACKGROUND

The incidence of attention deficit hyperactivity disorder is higher among children born very preterm than among children who are mature at birth.

METHODS

We studied 583 ten-year-old children who were born before 28 weeks of gestation whose IQ was above 84 and had a parent-completed Child Symptom Inventory-4, which allowed classification of the child as having or not having symptoms of attention deficit hyperactivity disorder. For 422 children, we also had a teacher report, and for 583 children, we also had a parent report of whether or not a physician made an attention deficit hyperactivity disorder diagnosis.

RESULTS

The risk profile of screening positive for attention deficit hyperactivity disorder based on a parent's report differed from the risk profile based on the teacher's report, whereas the risk profile according to a physician and according to any two observers closely resembled the parent-reported profile. Among the statistically significant risk factors were young maternal age (parent, physician, and two observers), maternal obesity (parent, physician, and two observers), maternal smoking (parent, physician, and two observers), magnesium given at delivery for seizure prophylaxis (parent and two observers), recovery of Mycoplasma sp. from the placenta (teacher and two observers), low gestational age (parent and two observers), low birth weight (teacher and physician), singleton (parent, physician, and two observers), male (parent, teacher, physician, and two observers), mechanical ventilation on postnatal day seven (physician), receipt of a sedative (parent and two observers), retinopathy of prematurity (parent), necrotizing enterocolitis (physician), antibiotic receipt (physician and two observers), and ventriculomegaly on brain scan (parent and two observers).

CONCLUSIONS

The multiplicity of risk factors identified can be subsumed as components of four broad themes: low socioeconomic state, immaturity or vulnerability, inflammation, and epigenetic phenomena.

Human brain organoid-on-a-chip to model prenatal nicotine exposure

Nicotine has been recognized to trigger various neuronal disabilities in the fetal brain and long-lasting behavioral deficits in offspring. However, further understanding of fetal brain development under nicotine exposure is challenging due to the limitations of existing animal models. Here, we create a new brain organoid-on-a-chip system derived from human induced pluripotent stem cells (hiPSCs) that allows us to model neurodevelopmental disorders under prenatal nicotine exposure (PNE) at early stages. The brain organoid-on-a-chip system facilitates 3D culture, in situ neural differentiation, and self-organization of brain organoids under continuous perfused cultures in a controlled manner. The generated brain organoids displayed well-defined neural differentiation, regionalization, and cortical organization, which recapitulates the key features of the early stages of human brain development. The brain organoids exposed to nicotine exhibited premature neuronal differentiation with enhanced expression of the neuron marker TUJ1. Brain regionalization and cortical development were disrupted in the nicotine-treated organoids identified by the expressions of forebrain (PAX6 and FOXG1), hindbrain (PAX2 and KROX20) and cortical neural layer (preplate TBR1 and deep-layer CTIP2) markers. Moreover, the neurite outgrowth showed abnormal neuronal differentiation and migration in nicotine-treated brain organoids. These results suggest that nicotine exposure elicits impaired neurogenesis in early fetal brain development during gestation. The established brain organoid-on-a-chip system provides a promising platform to model neurodevelopmental disorders under environmental exposure, which can be extended for applications in brain disease studies and drug testing.

Evidence of altered brain regulatory gene expression in tobacco-exposed fetuses

AIM

We sought to determine the association between prenatal smoking status and expression of fetal brain regulatory genes.

METHODS

At delivery, we collected information from parturient women on prenatal smoking habits and analyzed salivary cotinine levels. We obtained neonatal umbilical cord blood and extracted total RNA. We then employed the quantitative polymerase chain reaction (QPCR) analyses and the comparative CT method to calculate the relative gene expression of selected fetal brain regulatory genes responsible for (1) brain growth (brain-derived neutrotrophic factor, BDNF), (2) myelination (proteolipidic protein 1, PLP1 and myelin basic protein, MBP), and (3) neuronal migration and cell-cell interactions during fetal brain development or RLN. The χ2-test, analysis of variance (ANOVA), and the Grubb test were used to evaluate the relationship between prenatal smoking status and relative gene expression levels. Further analysis using bootstrapping was performed to assess the precision of our estimates.

RESULTS

Of the 39 maternal-infant dyads included in this study, 25.6% were non-smokers, 43.6% were passive smokers and 30.8% were active smokers. The results showed down-regulation of the selected fetal brain regulatory genes among active smokers.

CONCLUSIONS

These findings represent preliminary evidence in humans that intrauterine tobacco exposure impacts fetal brain programming. Future studies are warranted to examine whether our findings represent potential mechanisms through which adverse childhood/adult-onset cognitive and behavioral outcomes that have been previously linked to intrauterine exposure occur.

Tobacco Use and Smoke Exposure in Children: New Trends, Harm, and Strategies to Improve Health Outcomes

PURPOSE OF REVIEW

Every day in the USA, approximately 4000 adolescents begin smoking and the adolescent brain is particularly susceptible to nicotine addiction. We present current pediatric trends on tobacco use and exposures, various new products used by adolescents, the adverse biological and behavioral effects of tobacco use and exposures, and tobacco control strategies to eliminate tobacco-related illnesses and deaths in the pediatric population.

RECENT FINDINGS

Twelve-20% of women continue to smoke during pregnancy. New research reveals cognitive differences and behavior-control disorders are seen in elementary school children from prenatal and postnatal exposures. Traditional cigarette smoking has decreased in adolescents; novel and appealing tobacco products have captured their attention, particularly electronic cigarettes, and rates double and often triple from middle to high school. Children with asthma and those living in multi-housing units have higher rates of secondhand smoke exposure than non-asthmatics and children living in single-home dwellings. There is no "safe or risk-free" level of tobacco use or exposure. Tobacco use and exposure in childhood and adolescence must be decreased using evidenced-based strategies to improve child health.

Trajectories of attention-deficit/hyperactivity disorder dimensions in adults

OBJECTIVE

There is a lack of available information on the trajectories of attention-deficit/hyperactivity disorder (ADHD) dimensions during adulthood. This study investigates the course and the predictors of change for each ADHD domain in a clinical sample of adults with ADHD.

METHOD

Adults with ADHD (n = 344) were followed up for 7 years, with a final retention rate of 66.0%. Trajectories of inattention, hyperactivity, and impulsivity and their potential predictors were examined.

RESULTS

On average, symptoms declined in all ADHD domains during follow-up. Despite this, rises in inattentive, hyperactive, and impulsive symptoms were observed in approximately 13%, 25%, and 17% of patients respectively. Different predictors influenced the trajectory of each ADHD dimension. Oppositional defiant disorder and social phobia were associated with the maintenance of symptoms, while alcohol use disorder was associated with both maintenance and rise of symptoms.

CONCLUSION

Unexpectedly, a rise in the symptoms after 7 years was not uncommon in adults with ADHD. Prevalent comorbidities have the potential to influence the neurodevelopment and the trajectory of ADHD. Therefore, such predictors should be investigated in population cohorts to better characterize the course of ADHD. Additionally, these findings may be relevant in prevention studies and in strategies for ADHD treatment.

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.

Exposure to low doses of 137cesium and nicotine during postnatal development modifies anxiety levels, learning, and spatial memory performance in mice

Radiation therapy is a major cause of long-term complications observed in survivors of pediatric brain tumors. However, the effects of low-doses of ionizing radiation (IR) to the brain are less studied. On the other hand, tobacco is one of the most heavily abused drugs in the world. Tobacco is not only a health concern for adults. It has also shown to exert deleterious effects on fetuses, newborns, children and adolescents. Exposure to nicotine (Nic) from smoking may potentiate the toxic effects induced by IR on brain development. In this study, we evaluated in mice the cognitive effects of concomitant exposure to low doses of internal radiation (¹³⁷Cs) and Nic during neonatal brain development. On postnatal day 10 (PND10), two groups of C57BL/6J mice were subcutaneously exposed to 137-Cesium (¹³⁷Cs) (4000 and 8000 Bq/kg) and/or Nic (100 μg/ml). At the age of two months, neurobehavior of mice was assessed. Results showed that exposure to IR-alone or in combination with Nic-increased the anxiety-like of the animals without changing the activity levels. Moreover, exposure to IR impaired learning and spatial memory. However, Nic administration was able to reverse this effect, but only at the low dose of ¹³⁷Cs.

Early Childhood Household Smoke Exposure Predicts Less Task-Oriented Classroom Behavior at Age 10

Secondhand tobacco smoke is considered a developmental neurotoxicant especially given underdeveloped vital systems in young children. An ecological test of its negative influence on brain development can be made by examining the prospective association between early childhood household smoke exposure and later classroom behavior. Using a longitudinal birth cohort, we examined the unique contribution of household tobacco smoke exposure to children’s subsequent classroom engagement at age 10. From child ages 1.5 to 7 years, parents of 2,055 participants from the Quebec Longitudinal Study of Child Development reported on household smoking by themselves and other home occupants. At age 10, fourth-grade teachers reported on the child’s classroom engagement. In terms of prevalence, 58% of parents reported that their children were never exposed to smoke in the home, while 34% and 8% of children were exposed to transient and continuous household smoke, respectively. Compared with never exposed children, those who were exposed to transient and continuous household smoke scored 13% and 9% of a standard deviation lower on classroom engagement in fourth grade, standardized B = −.128 (95% confidence interval = −.186, −.069) and standardized B = −.093 (95% confidence interval = −.144, −.043), respectively. Compared with their never exposed peers, children exposed to transient and continuous early childhood household smoke showed proportionately less classroom engagement, which reflects task-orientation, following directions, and working well autonomously and with others. This predisposition poses risks for high school dropout, which from a population health perspective is closely linked with at-risk lifestyle habits and unhealthy outcomes.