Pregnancy complications and obstetric suboptimality in association with autism spectrum disorders in children of the Nurses' Health Study II

Understanding the link between different types of maternal diabetes and the onset of autism spectrum disorders

Autism spectrum disorders (ASD) encompass a collection of neurodevelopmental disorders that exhibit impaired social interactions and repetitive stereotypic behaviors. Although the exact cause of these disorders remains unknown, it is widely accepted that both genetic and environmental factors contribute to their onset and progression. Recent studies have highlighted the potential negative impact of maternal diabetes on embryonic neurodevelopment, suggesting that intrauterine hyperglycemia could pose an additional risk to early brain development and contribute to the development of ASD. This paper presents a comprehensive analysis of the current research on the relationship between various forms of maternal diabetes, such as type 1 diabetes mellitus, type 2 diabetes mellitus, and gestational diabetes mellitus, and the likelihood of ASD in offspring. The study elucidates the potential mechanisms through which maternal hyperglycemia affects fetal development, involving metabolic hormones, immune dysregulation, heightened oxidative stress, and epigenetic alterations. The findings of this review offer valuable insights for potential preventive measures and evidence-based interventions targeting ASD.

Altered Intrinsic Brain Spontaneous Activities in Children With Autism Spectrum Disorder Comorbid ADHD

OBJECTIVE

The study involved 17 children with Autism Spectrum Disorder (ASD), 21 with ADHD, 30 with both (ASD + ADHD), and 28 typically developing children (TD).

METHODS

The amplitude of low-frequency fluctuations (ALFF) was measured as a regional brain function index. Intrinsic functional connectivity (iFC) was also analyzed using the region of interest (ROI) identified in ALFF analysis. Statistical analysis was done via one-way ANCOVA, Gaussian random field (GRF) theory, and post-hoc pair-wise comparisons.

RESULTS

The ASD + ADHD group showed increased ALFF in the left middle frontal gyrus (MFG.L) compared to the TD group. In terms of global brain function, the ASD group displayed underconnectivity in specific regions compared to the ASD + ADHD and TD groups.

CONCLUSION

The findings contribute to understanding the neural mechanisms underlying ASD + ADHD.

Inflammatory Conditions During Pregnancy and Risk of Autism and Other Neurodevelopmental Disorders

Background

Maternal inflammation can result from immune dysregulation and metabolic perturbations during pregnancy. Whether conditions associated with inflammation during pregnancy increase the likelihood of autism spectrum disorder (ASD) or other neurodevelopmental disorders (DDs) is not well understood.

Methods

We conducted a case-control study among children born in California from 2011 to 2016 to investigate maternal immune-mediated and cardiometabolic conditions during pregnancy and risk of ASD (n = 311) and DDs (n = 1291) compared with children from the general population (n = 967). Data on maternal conditions and covariates were retrieved from electronic health records. Maternal genetic data were used to assess a causal relationship.

Results

Using multivariable logistic regression, we found that mothers with asthma were more likely to deliver infants later diagnosed with ASD (odds ratio [OR] = 1.62, 95% CI: 1.15-2.29) or DDs (OR = 1.30, 95% CI: 1.02-1.64). Maternal obesity was also associated with child ASD (OR = 1.51, 95% CI: 1.07-2.13). Mothers with both asthma and extreme obesity had the greatest odds of delivering an infant later diagnosed with ASD (OR = 16.9, 95% CI: 5.13-55.71). These increased ASD odds were observed among female children only. Polygenic risk scores for obesity, asthma, and their combination showed no association with ASD risk. Mendelian randomization did not support a causal relationship between maternal conditions and ASD.

Conclusions

Inflammatory conditions during pregnancy are associated with risk for neurodevelopmental disorders in children. These risks do not seem to be due to shared genetic risk; rather, inflammatory conditions may share nongenetic risk factors with neurodevelopmental disorders. Children whose mothers have both asthma and obesity during pregnancy may benefit from earlier screening and intervention.

Hypertensive disorders of pregnancy and occurrence of ADHD, ASD, and epilepsy in the child: A meta-analysis

AIM

To synthesize epidemiologic literature pertaining to the association between preeclampsia (PE), attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and epilepsy.

METHOD

A systematic search of PubMed and Embase was performed supplemented by hand-searching of reference lists of eligible studies. Two independent reviewers screened abstracts following a prepared protocol. Data extraction and quality appraisal using the Newcastle Ottawa Scale were performed by an independent reviewer. PRISMA guidelines were followed throughout. Random-effects meta-analyses were performed. Adjusted pooled Odds Ratios and their 95% confidence intervals were reported.

RESULTS

Fifteen out of 121 identified studies were eligible for inclusion. Six reported adjusted estimates for ADHD, resulting in a pooled odds ratio of 1.29 (95% CI: 1.20, 1.38). Eight reported adjusted estimates for ASD, resulting in a pooled odds ratio of 1.27 (95% CI:1.22, 1.32). Three reported adjusted estimates for epilepsy, resulting in a pooled odds ratio of 1.35 (95% CI: 1.12, 1.63).

INTERPRETATION

Intrauterine exposure to PE increased the risk of ADHD, ASD, and epilepsy, though it is unclear whether the true association is with pre-term birth. To our knowledge, this is the first meta-analysis to quantify the association between PE and epilepsy. The results of this meta-analysis can inform screening strategies among children born to preeclamptic mothers for early identification and treatment.

Examining associations between prenatal biomarkers of oxidative stress and ASD-related outcomes using quantile regression

We examined associations between prenatal oxidative stress (OS) and child autism-related outcomes. Women with an autistic child were followed through a subsequent pregnancy and that younger sibling's childhood. Associations between glutathione (GSH), glutathione disulfide (GSSG), 8-oxo-deoxyguanine (8-OHdG), and nitrotyrosine and younger sibling Social Responsiveness Scale (SRS) scores were examined using quantile regression. Increasing GSH:GSSG (suggesting decreasing OS) was associated with minor increases in SRS scores (50th percentile β: 1.78, 95% CI: 0.67, 3.06); no other associations were observed. Results from this cohort with increased risk for autism do not support a strong relationship between OS in late pregnancy and autism-related outcomes. Results may be specific to those with enriched autism risk; future work should consider other timepoints and biomarkers.

Increased Nuclear FOXP2 Is Related to Reduced Neural Stem Cell Number and Increased Neurogenesis in the Dorsal Telencephalon of Embryos of Diabetic Rats through Histamine H1 Receptors

Diabetic rat embryos have increased cortical neurogenesis and neuron maturation, and their offspring presented altered neuron polarity, lamination, and diminished neuron excitability. The FOXP2 overexpression results in higher cortical neurogenesis by increasing the transition of radial glia to the intermediate progenitor. Similarly, histamine through H₁-receptor activation increases cortical neuron differentiation. Indeed, blocking the H₁-receptor by the systemic administration of chlorpheniramine to diabetic pregnant rats prevents increased neurogenesis. Here, we explore the relationship between the H₁-receptor and FOXP2 on embryo neurogenesis from diabetic dams. Through qRT-PCR, Western blot, immunohistofluorescence, and flow cytometry, we showed an increased FOXP2 expression and nuclear localization, a reduced Nestin expression and -positive cells number, and a higher PKCα expression in the cortical neuroepithelium of fourteen-day-old embryos from diabetic rats. Interestingly, this scenario was prevented by the chlorpheniramine systemic administration to diabetic pregnant rats at embryo day twelve. These data, together with the bioinformatic analysis, suggest that higher H₁-receptor activity in embryos under high glucose increases FOXP2 nuclear translocation, presumably through PKCα phosphorylation, impairing the transition of radial glia to intermediate progenitor and increasing neuron differentiation in embryos of diabetic rats.

Association between previous abortion history and risk of autism spectrum disorders among offspring: a meta-analysis

BACKGROUND

Previous studies have been showed an association between previous abortion history and risk of Autism spectrum disorders (ASD). However, there is still controversy about true effect estimate of the association.

PURPOSE

This meta-analysis aimed to evaluate the association between previous abortion history and the risk of ASD.

METHODS

A systematic search was performed using PubMed, Scopus, and Web of Sciences databases to identify potential studies published until December 2021. The presence of statistical heterogeneity was determined using the I2 value. In the case of substantial heterogeneity, the random-effects model meta-analysis was used to estimate the pooled relative risks. The publication bias was assessed using the Egger and Begg tests.

RESULTS

Thirteen studies with a total of 331,779 children remained in the present meta-analysis. The estimated odds ratio of the risk of ASD associated with previous abortion history was 1.64 (95% confidence interval [CI], 1.28-2.0; I2=61.7%) in adjusted studies and 1.10 (95% CI, 1.01-1.20; I2=0.0%) in crude studies, based on the random effect model. There was moderate heterogeneity in adjusted studies. The p values for Egger and Begg regression among children with ASD were 0.393 and 0.056, respectively.

CONCLUSION

This meta-analysis suggests that children born from mothers with a history of previous abortion have an increased risk of development of ASD compared to children of mothers without a history of previous abortion.

Association of maternal polygenic risk scores for mental illness with perinatal risk factors for offspring mental illness

We examined whether genetic risk for mental illness is associated with known perinatal risk factors for offspring mental illness to determine whether gene-environmental correlation might account for the associations of perinatal factors with mental illness. Among 8983 women with 19,733 pregnancies, we found that genetic risk for mental illness was associated with any smoking during pregnancy [attention-deficit hyperactivity disorder (ADHD) and overall genetic risk], breast-feeding for less than 1 month (ADHD, depression, and overall genetic risk), experience of intimate partner violence in the year before the birth (depression and overall genetic risk), and pregestational overweight or obesity (bipolar disorder). These results indicate that genetic risk may partly account for the association between perinatal conditions and mental illness in offspring.

Perinatal adversities in tuberous sclerosis complex: Determinants and neurodevelopmental outcomes

AIM

To examine the association between perinatal adversities and neurodevelopmental outcome in tuberous sclerosis complex (TSC).

METHOD

The Tuberous Sclerosis 2000 study is a prospective, longitudinal UK study of TSC. In phase 1, mutation type, TSC family history, tuber characteristics, presence of cardiac rhabdomyomas, seizure characteristics, and intellectual ability were assessed in 125 children affected with TSC (64 females, 61 males; median age 39mo, range 4-254). In phase 2, 88 participants (49 females, 39 males; median age 148mo, range 93-323) were assessed for neurodevelopmental outcomes including intellectual ability, autism spectrum disorder, and attention-deficit/hyperactivity disorder. Perinatal histories of 88 participants with TSC and 80 unaffected siblings were collected retrospectively using the Obstetric Enquiry Schedule and coded with a modified Gillberg Optimality Scale to measure levels of perinatal adversity. Data were analysed using Mann-Whitney U tests, Spearman's rank correlation, and linear regression with robust standard errors.

RESULTS

Children with familial TSC experienced significantly greater perinatal adversity than unaffected siblings. Perinatal adversity was higher in children with TSC-affected mothers than those with unaffected mothers. There was no significant association between perinatal adversities and neurodevelopmental outcomes after controlling for confounders.

INTERPRETATION

Maternal TSC is a significant marker of elevated perinatal risk in addition to risks incurred by fetal genotype. Pregnancies complicated by maternal or fetal TSC require higher vigilance, and mechanisms underlying increased perinatal adversity require further research.

WHAT THIS PAPER ADDS

Higher perinatal adversity is associated with familial tuberous sclerosis complex (TSC). Maternal TSC was associated with higher frequencies of several perinatal risk markers. Paternal TSC was not associated with higher levels of perinatal adversity. Perinatal adversity levels in TSC1 and TSC2 subgroups did not differ significantly. Perinatal adversities were not associated with neurodevelopmental outcomes.

Cardiometabolic Pregnancy Complications in Association With Autism-Related Traits as Measured by the Social Responsiveness Scale in ECHO

Prior work has examined associations between cardiometabolic pregnancy complications and autism spectrum disorder (ASD) but not how these complications may relate to social communication traits more broadly. We addressed this question within the Environmental Influences on Child Health Outcomes program, with 6,778 participants from 40 cohorts conducted from 1998-2021 with information on ASD-related traits via the Social Responsiveness Scale. Four metabolic pregnancy complications were examined individually, and combined, in association with Social Responsiveness Scale scores, using crude and adjusted linear regression as well as quantile regression analyses. We also examined associations stratified by ASD diagnosis, and potential mediation by preterm birth and low birth weight, and modification by child sex and enriched risk of ASD. Increases in ASD-related traits were associated with obesity (β = 4.64, 95% confidence interval: 3.27, 6.01) and gestational diabetes (β = 5.21, 95% confidence interval: 2.41, 8.02), specifically, but not with hypertension or preeclampsia. Results among children without ASD were similar to main analyses, but weaker among ASD cases. There was not strong evidence for mediation or modification. Results suggest that common cardiometabolic pregnancy complications may influence child ASD-related traits, not only above a diagnostic threshold relevant to ASD but also across the population.

Autism spectrum disorder and obstetric optimality: a twin study and meta-analysis of sibling studies

BACKGROUND

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with a strong genetic basis. Recent studies have suggested that its aetiology is also influenced by environmental factors. Some of the most examined environmental factors are obstetric complications. However, the results are inconsistent.

METHODS

We aimed to explore the association between obstetric complications and autism in a population-based twin sample using the Obstetric Enquiry Scale (OES), a scale that measures the presence or absence of pre-, peri- and neonatal factors. Additionally, we report the meta-analytic results for obstetrical factors reported in previously published sibling studies.

RESULTS

Our study included 115 cases pairs and 62 controls pairs and showed that children with autism and their unaffected co-twins present significantly more obstetric complications than controls (ASD vs. controls β 1.26, CI 95% 1.11-1.40 p < .001; unaffected co-twin vs. controls β 1.20, 95% CI 1.07-1.36 p < .003). However, we did not find statistically significant differences between children with ASD and their unaffected co-twins (β .96, 95% CI 0.85-1.09, p 0.55). Meta-analysis demonstrated that maternal hypertension (RR 1.35, CI 95% 1.23-1.48), uterine bleeding (RR 1.20 CI 95% 1.01-1.42) and exposure to antibiotic during pregnancy (1.11 CI 95% 1.00-1.22) increase risk of ASD.

CONCLUSIONS

This study confirms that children with ASD and their unaffected twins show more obstetric complications than controls. However, these complications do not distinguish between ASD twins and their unaffected co-twins. In addition, the meta-analysis showed little influence of birth factors on ASD which suggests a shared familial liability for both obstetric complications and autism, rather than a causal association.

Pregnant Mothers' Medical Claims and Associated Risk of Their Children being Diagnosed with Autism Spectrum Disorder

A retrospective analysis of administrative claims containing a diverse mixture of ages, ethnicities, and geographical regions across the United States was conducted in order to identify medical events that occur during pregnancy and are associated with autism spectrum disorder (ASD). The dataset used in this study is comprised of 123,824 pregnancies of which 1265 resulted in the child being diagnosed with ASD during the first five years of life. Logistic regression analysis revealed significant relationships between several maternal medical claims, made during her pregnancy and segmented by trimester, and the child's diagnosis of ASD. Having a biological sibling with ASD, maternal use of antidepressant medication and psychiatry services as well as non-pregnancy related claims such hospital visits, surgical procedures, and radiology exposure were related to an increased risk of ASD regardless of trimester. Urinary tract infections during the first trimester and preterm delivery during the second trimester were also related to an increased risk of ASD. Preventative and obstetrical care were associated with a decreased risk for ASD. A better understanding of the medical factors that increase the risk of having a child with ASD can lead to strategies to decrease risk or identify those children who require increased surveillance for the development of ASD to promote early diagnosis and intervention.

Diabetes during Pregnancy: A Maternal Disease Complicating the Course of Pregnancy with Long-Term Deleterious Effects on the Offspring. A Clinical Review

In spite of the huge progress in the treatment of diabetes mellitus, we are still in the situation that both pregestational (PGDM) and gestational diabetes (GDM) impose an additional risk to the embryo, fetus, and course of pregnancy. PGDM may increase the rate of congenital malformations, especially cardiac, nervous system, musculoskeletal system, and limbs. PGDM may interfere with fetal growth, often causing macrosomia, but in the presence of severe maternal complications, especially nephropathy, it may inhibit fetal growth. PGDM may also induce a variety of perinatal complications such as stillbirth and perinatal death, cardiomyopathy, respiratory morbidity, and perinatal asphyxia. GDM that generally develops in the second half of pregnancy induces similar but generally less severe complications. Their severity is higher with earlier onset of GDM and inversely correlated with the degree of glycemic control. Early initiation of GDM might even cause some increase in the rate of congenital malformations. Both PGDM and GDM may cause various motor and behavioral neurodevelopmental problems, including an increased incidence of attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Most complications are reduced in incidence and severity with the improvement in diabetic control. Mechanisms of diabetic-induced damage in pregnancy are related to maternal and fetal hyperglycemia, enhanced oxidative stress, epigenetic changes, and other, less defined, pathogenic mechanisms.

Short communication: Ex-vivo effects of fluoxetine on production of biomarkers for inflammation and neurodevelopment by the placenta

Fluoxetine is commonly prescribed during pregnancy but developmental exposure to the drug, like infection, is associated with sex-specific behavioral changes in the offspring. We evaluated the effects of Fluoxetine on production of biomarkers for inflammation (pro/anti-inflammatory cytokines) and neurodevelopment (Brain-Derived Neurotrophic Factor, BDNF) in the presence and absence of infection in female and male placenta explant cultures. In addition to minor anti-inflammatory effects of the drug, Fluoxetine had significant sex- and infection-dependent effects on BDNF production. Further studies are needed to determine the extent to which these observed changes occur in vivo and their impact on pregnancy and neurodevelopmental outcomes.

Autism Spectrum Disorder from the Womb to Adulthood: Suggestions for a Paradigm Shift

The wide spectrum of unique needs and strengths of Autism Spectrum Disorders (ASD) is a challenge for the worldwide healthcare system. With the plethora of information from research, a common thread is required to conceptualize an exhaustive pathogenetic paradigm. The epidemiological and clinical findings in ASD cannot be explained by the traditional linear genetic model, hence the need to move towards a more fluid conception, integrating genetics, environment, and epigenetics as a whole. The embryo-fetal period and the first two years of life (the so-called 'First 1000 Days') are the crucial time window for neurodevelopment. In particular, the interplay and the vicious loop between immune activation, gut dysbiosis, and mitochondrial impairment/oxidative stress significantly affects neurodevelopment during pregnancy and undermines the health of ASD people throughout life. Consequently, the most effective intervention in ASD is expected by primary prevention aimed at pregnancy and at early control of the main effector molecular pathways. We will reason here on a comprehensive and exhaustive pathogenetic paradigm in ASD, viewed not just as a theoretical issue, but as a tool to provide suggestions for effective preventive strategies and personalized, dynamic (from womb to adulthood), systemic, and interdisciplinary healthcare approach.

Prevention in Autism Spectrum Disorder: A Lifelong Focused Approach

Autism Spectrum Disorder (ASD) is a complex highly heritable disorder, in which multiple environmental factors interact with the genes to increase its risk and lead to variable clinical presentations and outcomes. Furthermore, the inherent fundamental deficits of ASD in social attention and interaction critically diverge children from the typical pathways of learning, "creating" what we perceive as autism syndrome during the first three years of life. Later in life, training and education, the presence and management of comorbidities, as well as social and vocational support throughout the lifespan, will define the quality of life and the adaptation of an individual with ASD. Given the overall burden of ASD, prevention strategies seem like a cost-effective endeavour that we have to explore. In this paper, we take a life course approach to prevention. We will review the possibilities of the management of risk factors from preconception until the perinatal period, that of early intervention in the first three years of life and that of effective training and support from childhood until adulthood.

Gestational diabetes induces behavioral and brain gene transcription dysregulation in adult offspring

The etiology of Autism Spectrum Disorders (ASD) includes a strong genetic component and a complicated environmental component. Recent evidence indicates that maternal diabetes, including gestational diabetes, is associated with an increased prevalence of ASD. While previous studies have looked into possible roles for maternal diabetes in neurodevelopment, there are few studies into how gestational diabetes, with no previous diabetic or metabolic phenotype, may affect neurodevelopment. In this study, we have specifically induced gestational diabetes in mice, followed by behavioral and molecular phenotyping of the mice offspring. Pregnant mice were injected with STZ a day after initiation of pregnancy. Glucose levels increased to diabetic levels between E7 and E14 in pregnancy in a subset of the pregnant animals. Male offspring of Gestational Diabetic mothers displayed increased repetitive behaviors with no dysregulation in the three-chambered social interaction test. RNA-seq analysis revealed a dysregulation in genes related to forebrain development in the frontal cortex and a dysregulation of a network of neurodevelopment and immune related genes in the striatum. Together, these results give evidence that gestational diabetes can induce changes in adulthood behavior and gene transcription in the brain.

Relationship of prenatal maternal obesity and diabetes to offspring neurodevelopmental and psychiatric disorders: a narrative review

Obesity and diabetes is a worldwide public health problem among women of reproductive age. This narrative review highlights recent epidemiological studies regarding associations of maternal obesity and diabetes with neurodevelopmental and psychiatric disorders in offspring, and provides an overview of plausible underlying mechanisms and challenges for future human studies. A comprehensive search strategy selected terms that corresponded to the domains of interest (maternal obesity, different types of diabetes, offspring cognitive functions and neuropsychiatric disorders). The databases searched for articles published between January 2010 and April 2019 were PubMed, Web of Science and CINAHL. Evidence from epidemiological studies strongly suggests that maternal pre-pregnancy obesity is associated with increased risks for autism spectrum disorder, attention-deficit hyperactivity disorder and cognitive dysfunction with modest effect sizes, and that maternal diabetes is associated with the risk of the former two disorders. The influence of maternal obesity on other psychiatric disorders is less well studied, but there are reports of associations with increased risks for offspring depression, anxiety, schizophrenia and eating disorders, at modest effect sizes. It remains unclear whether these associations are due to intrauterine mechanisms or explained by confounding family-based sociodemographic, lifestyle and genetic factors. The plausible underlying mechanisms have been explored primarily in animal models, and are yet to be further investigated in human studies.

Foetal oestrogens and autism

Elevated latent prenatal steroidogenic activity has been found in the amniotic fluid of autistic boys, based on measuring prenatal androgens and other steroid hormones. To date, it is unclear if other prenatal steroids also contribute to autism likelihood. Prenatal oestrogens need to be investigated, as they play a key role in synaptogenesis and corticogenesis during prenatal development, in both males and females. Here we test whether levels of prenatal oestriol, oestradiol, oestrone and oestrone sulphate in amniotic fluid are associated with autism, in the same Danish Historic Birth Cohort, in which prenatal androgens were measured, using univariate logistic regression (n = 98 cases, n = 177 controls). We also make a like-to-like comparison between the prenatal oestrogens and androgens. Oestradiol, oestrone, oestriol and progesterone each related to autism in univariate analyses after correction with false discovery rate. A comparison of standardised odds ratios showed that oestradiol, oestrone and progesterone had the largest effects on autism likelihood. These results for the first time show that prenatal oestrogens contribute to autism likelihood, extending the finding of elevated prenatal steroidogenic activity in autism. This likely affects sexual differentiation, brain development and function.

Systemic endocrinopathies (thyroid conditions and diabetes): impact on postnatal life of the offspring

Fetal programming may influence childhood and adult life, determining the risk of specific diseases. During earlier stages of pregnancy, the transfer of maternal thyroid hormones to the fetus is vital for adequate neurologic development. The presence of severe maternal thyroid dysfunction, particularly severe iodine deficiency, is devastating, leading to irreversible neurologic sequelae. Moreover, mild maternal thyroid conditions, such as a mild-to-moderate iodine deficiency, may also lead to milder neurologic and behavioral conditions later during the life of the offspring. Maternal dysglycemia due to pregestational or gestational diabetes mellitus is another common situation in which fetal development encounters a hostile environment. Hyperglycemia in utero may trigger metabolic conditions in the offspring, including abnormalities of glucose tolerance and weight excess. Physicians assisting pregnant women have to be aware about these conditions, because they may go unnoticed if not properly screened. Because an early diagnosis and appropriate management may prevent most of the possible negative consequences for the progeny, the prevention, early diagnosis, and proper management of these endocrine conditions should be offered to all women undergoing pregnancy. Here, we comprehensively review the current evidence about the effects of maternal thyroid dysfunction and maternal dysglycemia on the cognitive function and carbohydrate metabolism in the offspring, two prevalent conditions of utmost importance for the child's health and development.

Early alterations in a mouse model of Rett syndrome: the GABA developmental shift is abolished at birth

Genetic mutations of the Methyl-CpG-binding protein-2 (MECP2) gene underlie Rett syndrome (RTT). Developmental processes are often considered to be irrelevant in RTT pathogenesis but neuronal activity at birth has not been recorded. We report that the GABA developmental shift at birth is abolished in CA3 pyramidal neurons of Mecp2^-/y mice and the glutamatergic/GABAergic postsynaptic currents (PSCs) ratio is increased. Two weeks later, GABA exerts strong excitatory actions, the glutamatergic/GABAergic PSCs ratio is enhanced, hyper-synchronized activity is present and metabotropic long-term depression (LTD) is impacted. One day before delivery, maternal administration of the NKCC1 chloride importer antagonist bumetanide restored these parameters but not respiratory or weight deficits, nor the onset of mortality. Results suggest that birth is a critical period in RTT with important alterations that can be attenuated by bumetanide raising the possibility of early treatment of the disorder.

Maternal diabetes and hypertensive disorders in association with autism spectrum disorder

Previous studies have shown complications of pregnancy, often examined in aggregate, to be associated with autism spectrum disorder (ASD). Results for specific complications, such as maternal diabetes and hypertension, have not been uniformly consistent and should be investigated independently in relation to ASD in a large community-based sample. The Study to Explore Early Development (SEED), a US multisite case-control study, enrolled children born in 2003-2006 at 2-5 years of age. Children were classified into three groups based on confirmation of ASD (n = 698), non-ASD developmental delay (DD; n = 887), or controls drawn from the general population (POP; n = 979). Diagnoses of any diabetes or hypertensive disorder during pregnancy were identified from prenatal medical records and maternal self-report. Logistic regression models estimated adjusted odds ratios (aOR) and confidence intervals (CI) adjusting for maternal age, race/ethnicity, education, smoking during pregnancy, and study site. Models for hypertension were additionally adjusted for parity and plurality. Among 2,564 mothers, we identified 246 (9.6%) with any diabetes and 386 (15.1%) with any hypertension in pregnancy. After adjustment for covariates, any diabetes during pregnancy was not associated with ASD (aOR = 1.10 [95% CI 0.77, 1.56]), but any hypertension was associated with ASD (aOR = 1.69 [95% CI 1.26, 2.26]). Results were similar for DD, and any diabetes (aOR = 1.29 [95% CI 0.94, 1.78]) or any hypertension (aOR = 1.71 [95% CI 1.30, 2.25]). Some pregnancy complications, such as hypertension, may play a role in autism etiology and can possibly serve as a prompt for more vigilant ASD screening efforts. Autism Res 2019, 12: 967-975. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We studied if common complications in pregnancy are associated with autism spectrum disorder (ASD) in a large sample of mothers and children. Our results show an association between conditions marked by high blood pressure and ASD, but no association with conditions marked by high blood sugar and ASD. Associations were similar for children who had a developmental disorder that was not ASD, suggesting that this relationship may not be specific to ASD.

Risk and Protective Environmental Factors Associated with Autism Spectrum Disorder: Evidence-Based Principles and Recommendations

Autism Spectrum Disorder (ASD) is a complex condition with early childhood onset, characterized by a set of common behavioral features. The etiology of ASD is not yet fully understood; however, it reflects the interaction between genetics and environment. While genetics is now a well-established risk factor, several data support a contribution of the environment as well. This paper summarizes the conclusions of a consensus conference focused on the potential pathogenetic role of environmental factors and on their interactions with genetics. Several environmental factors have been discussed in terms of ASD risk, namely advanced parental age, assisted reproductive technologies, nutritional factors, maternal infections and diseases, environmental chemicals and toxicants, and medications, as well as some other conditions. The analysis focused on their specific impact on three biologically relevant time windows for brain development: the periconception, prenatal, and early postnatal periods. Possible protective factors that might prevent or modify an ASD trajectory have been explored as well. Recommendations for clinicians to reduce ASD risk or its severity have been proposed. Developments in molecular biology and big data approaches, which are able to assess a large number of coexisting factors, are offering new opportunities to disentangle the gene⁻environment interplay that can lead to the development of ASD.

Melatonin Enhances Proliferation and Modulates Differentiation of Neural Stem Cells Via Autophagy in Hyperglycemia

Dysfunction of neural stem cells (NSCs) has been linked to fetal neuropathy, one of the most devastating complications of gestational diabetes. Several studies have demonstrated that melatonin (Mel) exerted neuroprotective actions in various stresses. However, the role of autophagy and the involvement of Mel in NSCs in hyperglycemia (HG) have not yet been fully established. Here, we found that HG increased autophagy and autophagic flux of NSCs as evidenced by increasing LC3B II/I ratio, Beclin-1 expression, and autophagosomes. Moreover, Mel enhanced NSCs proliferation and self-renewal in HG with decreasing autophagy and activated mTOR signaling. Consistently, inhibition of autophagy by 3-Methyladenine (3-Ma) could assist Mel effects above, and induction of autophagy by Rapamycin (Rapa) could diminish Mel effects. Remarkably, HG induced premature differentiation of NSCs into neurons (Map2 positive cells) and astrocytes (GFAP positive cells). Furthermore, Mel diminished HG-induced premature differentiation and assisted NSCs in HG differentiation as that in normal condition. Coincidentally, inhibiting of NSCs autophagy by 3-Ma assisted Mel to modulate differentiation. However, increasing NSCs autophagy by Rapa disturbed the Mel effects and retarded NSCs differentiation. These findings suggested that Mel supplementation could contribute to mimicking normal NSCs proliferation and differentiation in fetal central nervous system by inhibiting autophagy in the context of gestational diabetes. Stem Cells 2019;37:504-515.

A perspective on pre-eclampsia and neurodevelopmental outcomes in the offspring: Does maternal inflammation play a role?

Pre-eclampsia is a leading cause of maternal death and maternal and perinatal morbidity. Whilst the clinical manifestations of pre-eclampsia often occur in late pregnancy, the molecular events leading into the onset of this disease are thought to originate in early pregnancy and result in insufficient placentation. Although the causative molecular basis of pre-eclampsia remains poorly understood, maternal inflammation is recognised as a core clinical feature. While the adverse effects of pre-eclampsia on maternal and fetal health in pregnancy is well-recognised, the long-term impact of pre-eclampsia exposure on the risk of autism spectrum disorder (ASD) in exposed offspring is a topic of on-going debate. In particular, a recent systematic review has reported an association between exposure to pre-eclampsia and increased risk of ASD, however the molecular basis of this association is unknown. Here we review recent evidence for; 1) maternal inflammation in pre-eclampsia; 2) epidemiological evidence for alterations in neurodevelopmental outcomes in offspring exposed to pre-eclampsia; 3) long-term changes in the brains of offspring exposed to pre-eclampsia; and 4) how maternal inflammation may lead to altered neurodevelopmental outcomes in pre-eclampsia exposed offspring. Finally, we discuss the implications of this for the development of future studies in this field.

Maternal SSRIs experience and risk of ASD in offspring: a review

Antidepressants are extensively used during pregnancy and associated with severe outcomes, including innate malformations, prematurity, and low birth weight, etc. A recent study suggested that prenatal exposure to antidepressants may impair child neurodevelopment process. Thus, the aim of this review is to investigate the potential association between prenatal use of selective 5-HT reuptake inhibitors (SSRIs) and the risk of autism spectrum disorders (ASDs). Twelve studies related to the linkage between SSRI exposure during pregnancy and ASD in children were explored and compiled. However, there is a knowledge gap concerning the potential link between gestational exposure to antidepressants and the risk of ASDs. Despite such limitations, the available data show that some signal exists and signifies that antenatal exposure to SSRIs may increase the risk of ASDs. Thus, there is a vital need for further, large and well-designed research to definitively evaluate the existence and the magnitude of this severe risk.

Family history of immune conditions and autism spectrum and developmental disorders: Findings from the study to explore early development

Numerous studies have reported immune system disturbances in individuals with autism and their family members; however, there is considerable variability in findings with respect to the specific immune conditions involved, their timing, and the family members affected and little understanding of variation by autism subphenotype. Using data from the Study to Explore Early Development (SEED), a multi-site case-control study of children born 2003-2006 in the United States, we examined the role of family history of autoimmune diseases, asthma, and allergies in autism spectrum disorder (ASD) as well as other developmental disorders (DD). We investigated maternal immune conditions during the pregnancy period, as well as lifetime history of these conditions in several family members (mother, father, siblings, and study child). Logistic regression analyses included 663 children with ASD, 984 children with DD, and 915 controls ascertained from the general population (POP). Maternal history of eczema/psoriasis and asthma was associated with a 20%-40% increased odds of both ASD and DD. Risk estimates varied by specific ASD subphenotypes in association with these exposures. In addition, children with ASD were more likely to have a history of psoriasis/eczema or allergies than POP controls. No association was observed for paternal history or family history of these immune conditions for either ASD or DD. These data support a link between maternal and child immune conditions and adverse neurodevelopmental outcomes, and further suggest that associations may differ by ASD phenotype of the child. Autism Research 2019, 12: 123-135. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Using data from a large multi-site study in the US-the Study to Explore Early Development-we found that women with a history of eczema/psoriasis and asthma are more likely to have children with ASD or DD. In addition, children with ASD are more likely to have a history of psoriasis/eczema or allergies than typically developing children. These data support a link between maternal and child immune conditions and adverse neurodevelopmental outcomes.

Immune Abnormalities in Autism Spectrum Disorder-Could They Hold Promise for Causative Treatment?

Autism spectrum disorders (ASD) are characterized by impairments in language and communication development, social behavior, and the occurrence of stereotypic patterns of behavior and interests. Despite substantial speculation about causes of ASD, its exact etiology remains unknown. Recent studies highlight a link between immune dysfunction and behavioral traits. Various immune anomalies, including humoral and cellular immunity along with abnormalities at the molecular level, have been reported. There is evidence of altered immune function both in cerebrospinal fluid and peripheral blood. Several studies hypothesize a role for neuroinflammation in ASD and are supported by brain tissue and cerebrospinal fluid analysis, as well as evidence of microglial activation. It has been shown that immune abnormalities occur in a substantial number of individuals with ASD. Identifying subgroups with immune system dysregulation and linking specific cellular immunophenotypes to different symptoms would be key to defining a group of patients with immune abnormalities as a major etiology underlying behavioral symptoms. These determinations would provide the opportunity to investigate causative treatments for a defined patient group that may specifically benefit from such an approach. This review summarizes recent insights into immune system dysfunction in individuals with ASD and discusses the potential implications for future therapies.

Association of Hypertensive Disorders of Pregnancy With Risk of Neurodevelopmental Disorders in Offspring: A Systematic Review and Meta-analysis

Importance

Although research suggests an association between hypertensive disorders of pregnancy (HDP) and autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and other neurodevelopmental disorders in offspring, consensus is lacking. Given the increasing prevalence of hypertension in pregnancy, it is important to examine the association of HDP with neurodevelopmental outcome.

Objective

To synthesize the published literature on the association between HDP and risk of neurodevelopmental disorders in offspring in a systematic review and meta-analysis.

Data Sources

On the basis of a preprepared protocol, a systematic search of PubMed, CINAHL, Embase, PsycINFO, and Web of Science was performed from inception through June 7, 2017, supplemented by hand searching of reference lists.

Study Selection

Two investigators independently reviewed titles, abstracts, and full-text articles. English-language cohort and case-control studies were included in which HDP and neurodevelopmental disorders were reported.

Data Extraction and Synthesis

Data extraction and quality appraisal were performed independently by 2 reviewers. Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed throughout.

Main Outcomes and Measures

Random-effects meta-analyses of estimated pooled odds ratios (ORs) for HDP and ASD and for HDP and ADHD. Stand-alone estimates were reported for all other neurodevelopmental disorders.

Results

Of 1166 studies identified, 61 unique articles met inclusion criteria. Twenty studies reported estimates for ASD. Eleven of these (including 777 518 participants) reported adjusted estimates, with a pooled adjusted OR of 1.35 (95% CI, 1.11-1.64). Ten studies reported estimates for ADHD. Six of these (including 1 395 605 participants) reported adjusted estimates, with a pooled adjusted OR of 1.29 (95% CI, 1.22-1.36). Subgroup analyses according to type of exposure (ie, preeclampsia or other HDP) showed no statistically significant differences for ASD or ADHD. Thirty-one studies met inclusion criteria for all other neurodevelopmental disorders. Individual estimates reported for these were largely inconsistent, with few patterns of association observed.

Conclusions and Relevance

Exposure to HDP may be associated with an increase in the risk of ASD and ADHD. These findings highlight the need for greater pediatric surveillance of infants exposed to HDP to allow early intervention that may improve neurodevelopmental outcome.

Understanding environmental contributions to autism: Causal concepts and the state of science

The complexity of neurodevelopment, the rapidity of early neurogenesis, and over 100 years of research identifying environmental influences on neurodevelopment serve as backdrop to understanding factors that influence risk and severity of autism spectrum disorder (ASD). This Keynote Lecture, delivered at the May 2016 annual meeting of the International Society for Autism Research, describes concepts of causation, outlines the trajectory of research on nongenetic factors beginning in the 1960s, and briefly reviews the current state of this science. Causal concepts are introduced, including root causes; pitfalls in interpreting time trends as clues to etiologic factors; susceptible time windows for exposure; and implications of a multi-factorial model of ASD. An historical background presents early research into the origins of ASD. The epidemiologic literature from the last fifteen years is briefly but critically reviewed for potential roles of, for example, air pollution, pesticides, plastics, prenatal vitamins, lifestyle and family factors, and maternal obstetric and metabolic conditions during her pregnancy. Three examples from the case-control CHildhood Autism Risks from Genes and the Environment Study are probed to illustrate methodological approaches to central challenges in observational studies: capturing environmental exposure; causal inference when a randomized controlled clinical trial is either unethical or infeasible; and the integration of genetic, epigenetic, and environmental influences on development. We conclude with reflections on future directions, including exposomics, new technologies, the microbiome, gene-by-environment interaction in the era of -omics, and epigenetics as the interface of those two. As the environment is malleable, this research advances the goal of a productive and fulfilling life for all children, teen-agers and adults. Autism Res 2018, 11: 554-586. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

This Keynote Lecture, delivered at the 2016 meeting of the International Society for Autism Research, discusses evidence from human epidemiologic studies of prenatal factors contributing to autism, such as pesticides, maternal nutrition and her health. There is no single cause for autism. Examples highlight the features of a high-quality epidemiology study, and what comprises a compelling case for causation. Emergent research directions hold promise for identifying potential interventions to reduce disabilities, enhance giftedness, and improve lives of those with ASD.

Maternal Diabetes and Fetal Programming Toward Neurological Diseases: Beyond Neural Tube Defects

The purpose of this review was to search for experimental or clinical evidence on the effect of hyperglycemia in fetal programming to neurological diseases, excluding evident neural tube defects. The lack of timely diagnosis and the inadequate control of diabetes during pregnancy have been related with postnatal obesity, low intellectual and verbal coefficients, language and motor deficits, attention deficit with hyperactivity, problems in psychosocial development, and an increased predisposition to autism and schizophrenia. It has been proposed that several childhood or adulthood diseases have their origin during fetal development through a phenomenon called fetal programming. However, not all the relationships between the outcomes mentioned above and diabetes during gestation are clear, well-studied, or have been related to fetal programming. To understand this relationship, it is imperative to understand how developmental processes take place in health, in order to understand how the functional cytoarchitecture of the central nervous system takes place; to identify changes prompted by hyperglycemia, and to correlate them with the above postnatal impaired functions. Although changes in the establishment of patterns during central nervous system fetal development are related to a wide variety of neurological pathologies, the mechanism by which several maternal conditions promote fetal alterations that contribute to impaired neural development with postnatal consequences are not clear. Animal models have been extremely useful in studying the effect of maternal pathologies on embryo and fetal development, since obtaining central nervous system tissue in humans with normal appearance during fetal development is an important limitation. This review explores the state of the art on this topic, to help establish the way forward in the study of fetal programming under hyperglycemia and its impact on neurological and psychiatric disorders.

Developmental vitamin D deficiency and autism: Putative pathogenic mechanisms

Autism is a neurodevelopmental disease that presents in early life. Despite a considerable amount of studies, the neurobiological mechanisms underlying autism remain obscure. Both genetic and environmental factors are involved in the development of autism. Vitamin D deficiency is emerging as a consistently reported risk factor in children. One reason for the prominence now being given to this risk factor is that it would appear to interact with several other epidemiological risk factors for autism. Vitamin D is an active neurosteroid and plays crucial neuroprotective roles in the developing brain. It has important roles in cell proliferation and differentiation, immunomodulation, regulation of neurotransmission and steroidogenesis. Animal studies have suggested that transient prenatal vitamin D deficiency is associated with altered brain development. Here we review the potential neurobiological mechanisms linking prenatal vitamin D deficiency and autism and also discuss what future research targets must now be addressed.

Association of maternal diabetes with autism spectrum disorders in offspring: A systemic review and meta-analysis

Studies on the association of maternal diabetes with autism spectrum disorders (ASDs) in offspring provide inconsistent findings; therefore an updated and comprehensive literature review and meta-analysis is necessary to perform in order to evaluate the available evidences.After searching databases systematically, we established the inclusion criteria and selected the eligible studies. In both overall and stratified analyses, the estimated effects were synthesized dependent on the presence or absence of heterogeneity.Twelve articles involving 16 studies were included and synthesized, demonstrating a significant association of maternal diabetes with ASDs among children (relative risk [RR] = 1.48). However, high heterogeneity was observed (I = 56.3%) and publication bias was identified. In terms of the analyses on reliable evidences from case-control studies, heterogeneity and publication bias disappeared, and the risk of ASDs was increased by 62% among diabetic mothers compared with non-diabetic mothers.Maternal diabetes, especially gestational diabetes mellitus, is associated with ASDs in offspring based on a limited number of convincing case-control studies. More large-scale population-based prospective studies are still needed to draw firm conclusions.

Association between hypertensive disorders of pregnancy and risk of autism in offspring: a systematic review and meta-analysis of observational studies

Background

Autism spectrum disorder (ASD) is a common severe pervasive neurodevelopmental disorder of undetermined etiology. Environmental exposures, especially pregnancy complications, have been increasingly recognized as a potential risk factor for ASD. Our aim was to (1) systematically evaluate the association between hypertensive disorders of pregnancy (HDP) and the risk of ASD in offspring, (2) specifically draw a subgroup analysis of disease severity in patients with HDP to achieve more sufficient evidence on this issue.

Results

A total of 21 studies were identified with more than 6.5 million participants, including 31,027 ASD probands. A comparative meta-analysis established that offspring born premature to HDP were significantly associated with ASD than matched controls (OR = 1.42, 95% CI: 1.34–1.50). Subgroup analysis of clinical classification include: (1) gestational hypertension, (2) pre-eclampsia, (3) chronic hypertension complicating pregnancy (CHP). The offspring of mothers with pre-eclampsia and CHP have slightly higher risk (OR = 1.43; OR = 1.48, respectively) of ASD than those of mothers with gestational hypertension (OR = 1.37). In consistence with most previous researches, higher ASD prevalence was observed in male than female (OR = 1.38), indicating a potential role for gender in the pathophysiology of ASD.

Materials and Methods

We conducted a systematic literature search on PubMed, EMBASE, Web of Science, PsycINFO database and China National Knowledge Infrastructure up to Jun. 2017. Statistical analysis was performed using Stata 10.0.

Conclusions

This meta-analysis implies a possible link between HDP and the risk of ASD in offspring. However, further investigation should be conducted to confirm this conclusion, and intensive prenatal surveillance and early prediction for ASD is needed.

Exposure to Hypertensive Disorders of Pregnancy Increases the Risk of Autism Spectrum Disorder in Affected Offspring

There is growing awareness that prenatal adversity may increase the risk of autism spectrum disorder (ASD). Here, we examined the association between hypertensive disorders of pregnancy (HDP) and ASD risk at 7 years of age using the Millennium Cohort Study (MCS), a representative cohort of 13,192 children born in the UK from 2000 to 2001. We also sought to examine cytokine expression in the serum of women with pre-eclampsia, which is the most common HDP, and whether exposure of foetal neurons to this serum could change patterns of neuronal growth. HDP were reported by mothers 9 months post-delivery. ASD was parent reported at age seven, based on a doctor or health care professional's diagnosis. Weighted logistic regression was used for data analysis, adjusting for several potential confounders including maternal alcohol consumption, education, depression, age, and poverty status. Sensitivity analyses were performed excluding pre-term births, small for gestational age (SGA), and pre-pregnancy hypertension and depression. There was a significant association between HDP and a twofold increased risk of ASD (AOR = 2.10 [95% CI 1.20-3.70]). Excluding preterm births, SGA births, and offspring of women who had pre-pregnancy hypertension or over the age of 40 did not change the results materially. At the cellular level, exposure of foetal cortical neurons to 3% serum isolated from women with an established HDP increased neuronal growth and branching in vitro. These findings indicate that HDP exposure may increase the risk of ASD in the offspring.

The association between air pollutants and autism spectrum disorders

Autism spectrum disorders are a member of the pervasive developmental disorders (PDDs) that have been increasing dramatically since described by Leo Kanner in 1943. In the past decade, the number of epidemiological publications addressing air pollution exposures and autism has grown correspondingly, but the association is still unclear. Whether air pollutants play a causal role and which substances are related with autism requires further study. We systematically reviewed the literature from 2005 to 2016 in MEDLINE (National Library of Medicine), Web of Science, and PubMed and summarized the association between different air pollutants and autism. Furthermore, we further discussed the exposure time window and potential confounders that should be considered in the association analysis studies. Our objective is to summarize the association between different air pollutants and autism with literature, which has been published since 2005, and explore whether the exposure time window and potential confounders have influence on this association. These results could provide more comprehensive information about the association between air pollutants and autism and be helpful towards further validation study. Graphical abstract ᅟ.

The Changing Epidemiology of Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with lifelong impacts. Genetic and environmental factors contribute to ASD etiology, which remains incompletely understood. Research on ASD epidemiology has made significant advances in the past decade. Current prevalence is estimated to be at least 1.5% in developed countries, with recent increases primarily among those without comorbid intellectual disability. Genetic studies have identified a number of rare de novo mutations and gained footing in the areas of polygenic risk, epigenetics, and gene-by-environment interaction. Epidemiologic investigations focused on nongenetic factors have established advanced parental age and preterm birth as ASD risk factors, indicated that prenatal exposure to air pollution and short interpregnancy interval are potential risk factors, and suggested the need for further exploration of certain prenatal nutrients, metabolic conditions, and exposure to endocrine-disrupting chemicals. We discuss future challenges and goals for ASD epidemiology as well as public health implications.

Environmental factors associated with autism spectrum disorder: a scoping review for the years 2003-2013

INTRODUCTION

The number of children diagnosed with autism spectrum disorder (ASD) has been rapidly rising in the past decade. The etiology of this disorder, however, is largely unknown, although the environmental relative to the genetic contribution is substantial. We conducted a scoping review to comprehensively assess the current state of knowledge of the environmental factors present from preconception to early life associated with ASD, and to identify research gaps.

METHODS

We searched electronic databases MEDLINE, PsycINFO and ERIC for articles on potential risk factors or protective factors from the physical and social environments associated with ASD and its subclassifications published between 1 January, 2003, and 12 July, 2013. We categorized articles into broad themes: chemical, physiological, nutritional and social factors, based on environmental exposure.

RESULTS

We identified over 50 000 publications, but after ineligible studies were screened out, 315 articles remained. Most of these studies examined physiological factors, followed closely by chemical factors, and to a much lesser extent, nutritional and social factors, associated with ASD. Despite a vast literature and many heterogeneous studies, several risk factors emerged consistently: chemical factors such as traffic-related air pollutants; physiological factors including advanced parental age, preterm birth, low birth weight, hyperbilirubinemia and clustering of pregnancy complications; and maternal immigrant status. Despite extensive research on vaccines, findings overwhelmingly demonstrate no support for an association with ASD.

CONCLUSION

The lack of consistency, temporality and specificity of associations between environmental factors and ASD remains the largest barrier to establishing causal relationships. More robust research is required to resolve inconsistencies in the literature. Future research should explore underlying mechanisms of associations between the risk factors that we identified and ASD.

Fetal origins of autism spectrum disorders: the non-associated maternal factors

Aim:

Several population-based studies have been conducted to determine whether maternal exposures are involved in the pathophysiology of autism spectrum disorder (ASD). We review these studies and describe the factors not associated with increased risk for ASD development.

Methods:

We identified studies describing associations between maternal exposures and ASD development. These studies include the Childhood Autism Risks from Genetics and the Environment, Nurses’ Health Study II, and the Swedish population registry.

Results:

Factors not associated with ASD development include Type 2 and gestational diabetes, chronic hypertension, fever treated with antipyretic medication, autoimmune disease and short interpregnancy intervals.

Conclusion:

There is increasing evidence that maternal exposures are involved in the pathophysiology of ASD in the developing fetus.

Lay Abstract: Autism spectrum disorder currently affects one in 68 children in the USA, with up to one in 42 boys. Its underlying etiology is largely unknown. Although autism was once considered a childhood disease, efforts for early detection led to the realization that it might originate at a much earlier stage, namely fetal life. Several maternal risk factors have recently been studied to establish associations with autism in the offspring. In this review, we present the maternal risk factors that were not found to have such associations.

Is the Risk of Autism in Younger Siblings of Affected Children Moderated by Sex, Race/Ethnicity, or Gestational Age?

OBJECTIVE

To evaluate the recurrence risk of autism spectrum disorders (ASD) in younger siblings of affected children and determine how it is modified by race/ethnicity and sex.

METHOD

Medical records of children born in a large health maintenance organization (Kaiser Permanent Southern California) hospitals from January 1, 2001, through December 31, 2010, and who remained in our system until 2 to 11 years of age were used to assess the risk of recurrence of ASD in younger siblings. Children born at <28 or >42 weeks gestation, multiple births, or those who were not active members for ≥3 months were excluded. ASD diagnosis was ascertained from DSM-IV codes, and the magnitude of the association was estimated using adjusted relative risks (aRRs).

RESULTS

Among eligible younger siblings, 592 (1.11%) had the diagnosis of ASD. The ASD rates were 11.30% and 0.92% for younger siblings of older affected and unaffected siblings, respectively (aRR: 14.27; 95% confidence interval, 11.41-17.83). This association remained after adjusting for potential confounding factors. Race/ethnicity- and gestational age-specific analyses revealed a positive association of similar magnitude across groups. Risk remained higher in younger boys than girls regardless of the sex of affected older siblings.

CONCLUSION

The findings of this study suggest that the risk of ASD in younger siblings is higher if the older sibling has ASD. The risk of ASD in younger siblings of older affected siblings was comparable across gestational age at birth and child's race/ethnicity groups. However, risk remains higher for boys. This study contributes to a better understanding of the influence of race/ethnicity, sex, and gestational age at birth in identifying children at higher risk of ASD.

Genetic Syndromes, Maternal Diseases and Antenatal Factors Associated with Autism Spectrum Disorders (ASD)

Autism spectrum disorder (ASD) affecting about 1% of all children is associated, in addition to complex genetic factors, with a variety of prenatal, perinatal, and postnatal etiologies. In addition, ASD is often an important clinical presentation of some well-known genetic syndromes in human. We discuss these syndromes as well as the role of the more important prenatal factors affecting the fetus throughout pregnancy which may also be associated with ASD. Among the genetic disorders we find Fragile X, Rett syndrome, tuberous sclerosis, Timothy syndrome, Phelan-McDermid syndrome, Hamartoma tumor syndrome, Prader-Willi and Angelman syndromes, and a few others. Among the maternal diseases in pregnancy associated with ASD are diabetes mellitus (PGDM and/or GDM), some maternal autoimmune diseases like antiphospholipid syndrome (APLS) with anti-β2GP1 IgG antibodies and thyroid disease with anti-thyroid peroxidase (TPO) antibodies, preeclampsia and some other autoimmune diseases with IgG antibodies that might affect fetal brain development. Other related factors are maternal infections (rubella and CMV with fetal brain injuries, and possibly Influenza with fever), prolonged fever and maternal inflammation, especially with changes in a variety of inflammatory cytokines and antibodies that cross the placenta and affect the fetal brain. Among the drugs are valproic acid, thalidomide, misoprostol, and possibly SSRIs. β2-adrenergic receptor agonists and paracetamol have also lately been associated with increased rate of ASD but the data is too preliminary and inconclusive. Associations were also described with ethanol, cocaine, and possibly heavy metals, heavy smoking, and folic acid deficiency. Recent studies show that heavy exposure to pesticides and air pollution, especially particulate matter < 2.5 and 10 μm in diameter (PM2.5 and PM10) during pregnancy is also associated with ASD. Finally, we have to remember that many of the associations mentioned in this review are only partially proven, and not all are "clean" of different confounding factors. The associations described in this review emphasize again how little we know about the etiology and pathogenesis of ASD. It is obvious that we need more epidemiologic data to establish many of these associations, but if proven, they might be promising avenues for prevention.

Air Pollution and Autism Spectrum Disorders: Causal or Confounded?

In the last decade, several studies have examined the association between perinatal exposure to ambient air pollution and risk of autism spectrum disorder (ASD). These studies have largely been consistent, with associations seen with different aspects of air pollution, including hazardous air toxics, ozone, particulate, and traffic-related pollution. Confounding by socioeconomic status (SES) and place of residence are of particular concern, as these can be related to ASD case ascertainment and other potential causal risk factors for ASD. While all studies take steps to address this concern, residual confounding is difficult to rule out. Two recent studies of air pollution and ASD, however, present findings that strongly argue against residual confounding, especially for factors that do not vary over relatively short time intervals. These two studies, conducted in communities around the USA, found a specific association with air pollution exposure during the 3rd, but not the 1st, trimester, when both trimesters were modeled simultaneously. In this review, we discuss confounding possibilities and then explain-with the aid of directed acyclic graphs (DAGs)-why an association that is specific to a particular time window, when multiple exposure windows are simultaneously assessed, argues against residual confounding by (even unmeasured) non-time-varying factors. In addition, we discuss why examining ambient air pollution concentration as a proxy for personal exposure helps avoid confounding by personal behavior differences, and the implications of measurement error in using ambient concentrations as a proxy for personal exposures. Given the general consistency of findings across studies and the exposure-window-specific associations recently reported, the overall evidence for a causal association between air pollution and ASD is increasingly compelling.

Maternal metabolic risk factors for autism spectrum disorder-An analysis of electronic medical records and linked birth data

Past studies have suggested that conditions experienced by women during pregnancy (e.g. obesity and gestational diabetes mellitus (GDM)) may be associated with having a child with autism spectrum disorder (ASD). Our objective was to compare mothers who had a child diagnosed with ASD to mothers of children with a non-ASD developmental disorder (DD) or without any reported DD (controls). To accomplish the objective we collected medical record data from patients who resided in the Cincinnati Children's Hospital Medical Center's (CCHMC) primary catchment area and linked those data to data from birth certificates (to identify risk factors). Two comparison groups were analyzed; one with DD; and the other, controls without a reported ASD or DD. Descriptive statistics and regression analyses evaluated differences. Differences were greater comparing mothers of ASD to controls than comparing ASD to DD. Maternal obesity and GDM were associated with a statistically significant approximately 1.5-fold increased odds of having a child with an ASD. For mothers with both GDM and obesity, the association was twofold for having a child with ASD compared with controls. Maternal obesity and GDM might be associated with an increased risk of ASD in the offspring; however, no difference in risk of ASD according to BMI and GDM was seen when comparing to DD. Autism Res 2016, 9: 829-837,. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

A review of executive function deficits in autism spectrum disorder and attention-deficit/hyperactivity disorder

Executive dysfunction has been shown to be a promising endophenotype in neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). This article reviewed 26 studies that examined executive function comparing ASD and/or ADHD children. In light of findings from this review, the ASD + ADHD group appears to share impairment in both flexibility and planning with the ASD group, while it shares the response inhibition deficit with the ADHD group. Conversely, deficit in attention, working memory, preparatory processes, fluency, and concept formation does not appear to be distinctive in discriminating from ASD, ADHD, or ASD + ADHD group. On the basis of neurocognitive endophenotype, the common co-occurrence of executive function deficits seems to reflect an additive comorbidity, rather than a separate condition with distinct impairments.

Maternal high-fat diet programming of the neuroendocrine system and behavior

This article is part of a Special Issue "SBN 2014". Maternal obesity, metabolic state, and diet during gestation have profound effects on offspring development. The prevalence of neurodevelopmental and mental health disorders has risen rapidly in the last several decades in parallel with the rise in obesity rates. Evidence from epidemiological studies indicates that maternal obesity and metabolic complications increase the risk of offspring developing behavioral disorders such as attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASD), and schizophrenia. Animal models show that a maternal diet high in fat similarly disrupts behavioral programming of offspring, with animals showing social impairments, increased anxiety and depressive behaviors, reduced cognitive development, and hyperactivity. Maternal obesity, metabolic conditions, and high fat diet consumption increase maternal leptin, insulin, glucose, triglycerides, and inflammatory cytokines. This leads to increased risk of placental dysfunction, and altered fetal neuroendocrine development. Changes in brain development that likely contribute to the increased risk of behavioral and mental health disorders include increased inflammation in the brain, as well as alterations in the serotonergic system, dopaminergic system and hypothalamic-pituitary-adrenal (HPA) axis.

Advancing parental age and autism: multifactorial pathways

Converging evidence from epidemiological, genetic, and animal studies supports the hypothesis that advancing parental age, both of the father and mother, increases the risk of autism spectrum disorders (ASD) in offspring. Paternal age has received considerable attention, with whole-genome sequencing studies linking older fathers to higher rates of de novo mutations and increased risk of ASD. The current evidence suggests that the increased risk of ASD in the offspring of older mothers may be related to mechanisms different from those operating in older fathers. Causal pathways probably involve the interaction of multiple risk factors. Although the etiology of ASD is still poorly understood, studies of parental age provide clues into the genetic and environ-mental mechanisms that mediate the risk of ASD.

Maternal autoimmune diseases and the risk of autism spectrum disorders in offspring: A systematic review and meta-analysis

Although inherited and immune disorder factors are known to be involved in autism spectrum disorders (ASD), controversy still exists as to whether maternal autoimmune disease is an independent risk of ASD in offspring. We aimed to quantitatively summarize the risk of ASD in offspring in relation to maternal autoimmune diseases. A literature search in Pubmed, Web of science, Embase, and China national knowledge internet was conducted to identify relevant studies. Pooled odd ratio (OR) and its 95% confidence interval (CI) were computed by STATA version 12.0. Nine case-control studies and one cohort studies comprising 9775 cases and 952,211 controls were included in this study. A positive association between maternal autoimmune diseases and the risk of ASD in offspring was identified assuming a fixed effect model (pooled OR, 1.34; 95% CI, 1.23-1.46; I(2), 27.9%). There were statistically significant associations between maternal autoimmune diseases developed during pregnancy or maternal thyroid disease and the risk of ASD in offspring (pooled OR, 1.30, 1.29, respectively). Maternal autoimmune disease is likely to be an independent risk factor of ASD in offspring.