Environmental risk factors and biomarkers for autism spectrum disorder: an umbrella review of the evidence

The environmental risk factors associated with ectopic pregnancy: An umbrella review

INTRODUCTION

Ectopic pregnancy(EP) is the implantation of a fertilized ovum outside of the uterine cavity. The incidence of EP has steadily increased around the world. The present umbrella review evaluated risk factors prior to conception associated with EP based on meta-analyses and systematic reviews.

METHODS

We searched PubMed, Scopus, and Web of Science until June 25, 2021. All meta-analyses that had focused on assessing the risk factors associated with EP were included. We calculated summary effect estimates, 95% CI, heterogeneity I², 95% prediction interval, small-study effects, excess significance biases, and sensitive analysis. The quality of the meta-analyses was evaluated with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2).

RESULTS

Two risk factors including chlamydia trachomatis (OR: 3.03) and smoking (OR: 1·77) were graded as suggestive evidence (class III). IUD with pregnant control (OR: 10.63) and endometriosis for case-control studies (OR: 2·66) and tubal ligation with pregnant control (OR: 9.3) were graded as risk factors with weak evidence (class IV). Tubal ligation with non-pregnant control was a protective factor (class IV). IUD with non-pregnant control and endometriosis for cohort studies were not as risk factors for EP.

CONCLUSION

Two risk factors including chlamydia trachomatis and smoking were graded as suggestive evidence. IUD with pregnant control and endometriosis for case-control studies and tubal ligation with pregnant control were graded as risk factors with weak evidence. Strong evidence for risk factors of EP was not achieved, indicating the degree of uncertainty and bias, which bring an emergency to conduct further no-bias studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021281632).

Nutritional Status and Feeding Behavior of Children with Autism Spectrum Disorder in the Middle East and North Africa Region: A Systematic Review

Autism spectrum disorder (ASD) in children is associated with increased risks of overweight/obesity and underweight, altered nutrient profile, and abnormal feeding behaviors. This systematic review aimed to elucidate the literature on the nutritional status of children with ASD in the Middle East North Africa (MENA) region, by providing a summary and assessment of the body of evidence. A systematic review of English and Arabic publications up to November 2020 was conducted of five databases in addition to the grey literature, which include a nutrition-related parameter, from both experimental and observational study designs. Children with ASD (ASD-C) between 2 and 19 years in the MENA Region were the target population. For risk of bias, the Academy of Nutrition and Dietetics' Quality Criteria Checklist (QCC) was adopted. The number of published articles was grossly limited. Forty-three articles were included, of which only four articles reported a low risk of bias; therefore, the results were interpreted in light of methodological limitations. Both overweight and underweight were common in ASD-C, although not consistently different than typically developing children. Nutrient inadequacies of energy, protein, omega-3, and others; deficiencies in serum iron indicators and calcium, as well as vitamins B12, B9, and D levels; and higher levels of homocysteine and omega-6/omega-3 ratios were reported. Feeding behavior problems were also common in ASD-C. Understanding nutritional requirements and food preferences can guide the planning of the appropriate comprehensive interventions for ASD-C. Various nutritional and behavioral concerns were identified in the included studies; however, they were subject to methodological weaknesses, which limited the generalizability of these results. Future research is warranted that must be directed to finding strong evidence using robust study designs on nutritional status and feeding behaviors of ASD-C, with a particular emphasis on the MENA Region.

Autism Spectrum Disorder: A Review

IMPORTANCE

Autism spectrum disorder (ASD), characterized by deficits in social communication and the presence of restricted, repetitive behaviors or interests, is a neurodevelopmental disorder affecting approximately 2.3% children aged 8 years in the US and approximately 2.2% of adults. This review summarizes evidence on the diagnosis and treatment of ASD.

OBSERVATIONS

The estimated prevalence of ASD has been increasing in the US, from 1.1% in 2008 to 2.3% in 2018, which is likely associated with changes in diagnostic criteria, improved performance of screening and diagnostic tools, and increased public awareness. No biomarkers specific to the diagnosis of ASD have been identified. Common early signs and symptoms of ASD in a child's first 2 years of life include no response to name when called, no or limited use of gestures in communication, and lack of imaginative play. The criterion standard for the diagnosis of ASD is a comprehensive evaluation with a multidisciplinary team of clinicians and is based on semistructured direct observation of the child's behavior and semistructured caregiver interview focused on the individual's development and behaviors using standardized measures, such as the Autism Diagnostic Observation Schedule-Second Edition and the Autism Diagnostic Interview. These diagnostic measures have sensitivity of 91% and 80% and specificity of 76% and 72%, respectively. Compared with people without ASD, individuals with ASD have higher rates of depression (20% vs 7%), anxiety (11% vs 5%), sleep difficulties (13% vs 5%), and epilepsy (21% with co-occurring intellectual disability vs 0.8%). Intensive behavioral interventions, such as the Early Start Denver Model, are beneficial in children 5 years or younger for improvement in language, play, and social communication (small to medium effect size based on standardized mean difference). Pharmacotherapy is indicated for co-occurring psychiatric conditions, such as emotion dysregulation or attention-deficit/hyperactivity disorder. Risperidone and aripiprazole can improve irritability and aggression (standardized mean difference of 1.1, consistent with a large effect size) compared with placebo. Psychostimulants are effective for attention-deficit/hyperactivity disorder (standardized mean difference of 0.6, consistent with a moderate effect size) compared with placebo. These medications are associated with adverse effects including, most commonly, changes in appetite, weight, and sleep.

CONCLUSIONS AND RELEVANCE

ASD affects approximately 2.3% of children aged 8 years and approximately 2.2% of adults in the US. First-line therapy consists of behavioral interventions, while co-occurring psychiatric conditions, such as anxiety or aggression, may be treated with specific behavioral therapy or medication.

Interactions of genetic risks for autism and the broad autism phenotypes

Background

Common polygenic risk and de novo variants (DNVs) capture a small proportion of autism spectrum disorder (ASD) liability, and ASD phenotypic heterogeneity remains difficult to explain. Integrating multiple genetic factors contribute to clarifying the risk and clinical presentation of ASD.

Methods

In our study, we investigated the individual and combined effects of polygenic risk, damaging DNVs (including those in ASD risk genes), and sex among 2,591 ASD simplex families in the Simons Simplex Collection. We also explored the interactions among these factors, along with the broad autism phenotypes of ASD probands and their unaffected siblings. Finally, we combined the effects of polygenic risk, damaging DNVs in ASD risk genes, and sex to explain the total liability of ASD phenotypic spectrum.

Results

Our findings revealed that both polygenic risk and damaging DNVs contribute to an increased risk for ASD, with females exhibiting higher genetic burdens than males. ASD probands that carry damaging DNVs in ASD risk genes showed reduced polygenic risk. The effects of polygenic risk and damaging DNVs on autism broad phenotypes were inconsistent; probands with higher polygenic risk exhibited improvement in some behaviors, such as adaptive/cognitive behaviors, while those with damaging DNVs exhibited more severe phenotypes. Siblings with higher polygenic risk and damaging DNVs tended to have higher scores on broader autism phenotypes. Females exhibited more severe cognitive and behavioral problems compared to males among both ASD probands and siblings. The combination of polygenic risk, damaging DNVs in ASD risk genes, and sex explained 1-4% of the total liability of adaptive/cognitive behavior measurements.

Conclusion

Our study revealed that the risk for ASD and the autism broad phenotypes likely arises from a combination of common polygenic risk, damaging DNVs (including those in ASD risk genes), and sex.

Implication of Hippocampal Neurogenesis in Autism Spectrum Disorder: Pathogenesis and Therapeutic Implications

Autism spectrum disorder (ASD) is a cluster of heterogeneous neurodevelopmental conditions with atypical social communication and repetitive sensory-motor behaviors. The formation of new neurons from neural precursors in the hippocampus has been unequivocally demonstrated in the dentate gyrus of rodents and non-human primates. Accumulating evidence sheds light on how the deficits in the hippocampal neurogenesis may underlie some of the abnormal behavioral phenotypes in ASD. In this review, we describe the current evidence concerning pre-clinical and clinical studies supporting the significant role of hippocampal neurogenesis in ASD pathogenesis, discuss the possibility of improving hippocampal neurogenesis as a new strategy for treating ASD, and highlight the prospect of emerging pro-neurogenic therapies for ASD.

Global, regional, and national disease burden of autism spectrum disorder among children under 5 years from 1990 to 2019: An analysis for the Global Burden of Disease 2019 Study

AIM

To estimate the trend in burden of autism spectrum disorder (ASD) at global, regional, and national levels from 1990 to 2019.

METHODS

Annual incident cases, incidence rates, prevalent cases, prevalence rates, disability-adjusted life years (DALYs), and DALY rates of ASD among children under 5 years from 1990 to 2019 were collected from the Global Burden of Diseases Study 2019. The percentage of relative changes in cases and the estimated annual percentage changes (EAPCs) of rates were calculated to reflect the temporal trends of ASD burden. Pearson correlation analysis was used to explore the influential factors for EAPC.

RESULTS

Globally, the incidence rate, prevalence rate, and DALY rate of ASD among children under 5 years were 91.09 per 100,000, 439.39 per 100,000, and 68.67 per 100,000 in 2019, respectively. From 1990-2019, the incidence rate decreased (EAPC = -0.09, 95% confidence interval [CI] -0.12 to -0.06), whereas the prevalence rate (EAPC=0.08, 95%CI 0.06-0.09) and DALY rate (EAPC=0.08, 95%CI 0.07-0.10) increased. The largest increases in prevalent cases (80.26%) and DALYs (81.24%) were found in low SDI regions, while High-income North America experienced the fastest increase in incidence rate, prevalence rate, and DALY rate. Moreover, the burden of ASD among male children under 5 years was approximately three times that among female children, despite the slight narrowing of gender disparity. The EAPC of incidence rate was positively correlated with SDI and UHCI in 2019 (P < 0.001).

CONCLUSION

ASD is a noticeable child neurodevelopmental syndrome. More attention should be given to early screening, diagnosis, and intervention, particularly in resource-limited areas.

Unsaturated Fatty Acids in Mental Disorders: An Umbrella Review of Meta-Analyses

Unsaturated fatty acids might be involved in the prevention of and improvement in mental disorders, but the evidence on these associations has not been comprehensively assessed. This umbrella review aimed to appraise the credibility of published evidence evaluating the associations between unsaturated fatty acids and mental disorders. In this umbrella review, systematic reviews and meta-analyses of studies comparing unsaturated fatty acids (including supplementation, dietary intake, and blood concentrations) in participants with mental disorders with healthy individuals were included. We reanalyzed summary estimates, between-study heterogeneity, predictive intervals, publication bias, small-study effects, and excess significance bias for each meta-analysis. Ninety-five meta-analyses from 29 systematic reviews were included, encompassing 43 studies on supplementation interventions, 32 studies on dietary factors, and 20 studies on blood biomarkers. Suggestive evidence was only observed for dietary intake, in which higher intake of fish was associated with reduced risk of depression (RR: 0.78; 95% CI: 0.69, 0.89) and Alzheimer disease (RR: 0.74; 95% CI: 0.63, 0.87), and higher intake of total PUFAs might be associated with a lower risk of mild cognitive impairment (RR: 0.71; 95% CI: 0.61, 0.84). Evidence showed that PUFA supplementation was favorable but had weak credibility in anxiety, depression, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), dementia, mild cognitive impairment, Huntington's disease, and schizophrenia (P-random effects <0.001-0.040). There was also weak evidence on the effect of decreased circulating n-3 (ɷ-3) PUFAs among patients on risk of ADHD, ASD, bipolar disorder, and schizophrenia (P-random effects <10-6-0.037). Our results suggest that higher levels of unsaturated fatty acids may relieve symptoms or reduce the risk of various mental disorders; however, the strength of the associations and credibility of the evidence were generally weak. Future high-quality research is needed to identify whether PUFA interventions should be prioritized to alleviate mental disorders.

A comprehensive approach to modeling maternal immune activation in rodents

Prenatal brain development is a highly orchestrated process, making it a very vulnerable window to perturbations. Maternal stress and subsequent inflammation during pregnancy leads to a state referred to as, maternal immune activation (MIA). If persistent, MIA can pose as a significant risk factor for the manifestation of neurodevelopmental disorders (NDDs) such as autism spectrum disorder and schizophrenia. To further elucidate this association between MIA and NDD risk, rodent models have been used extensively across laboratories for many years. However, there are few uniform approaches for rodent MIA models which make not only comparisons between studies difficult, but some established approaches come with limitations that can affect experimental outcomes. Here, we provide researchers with a comprehensive review of common experimental variables and potential limitations that should be considered when designing an MIA study based in a rodent model. Experimental variables discussed include: innate immune stimulation using poly I:C and LPS, environmental gestational stress paradigms, rodent diet composition and sterilization, rodent strain, neonatal handling, and the inclusion of sex-specific MIA offspring analyses. We discuss how some aspects of these variables have potential to make a profound impact on MIA data interpretation and reproducibility.

Implications of oral streptococcal bacteriophages in autism spectrum disorder

Growing evidence suggests altered oral and gut microbiota in autism spectrum disorder (ASD), but little is known about the alterations and roles of phages, especially within the oral microbiota in ASD subjects. We enrolled ASD (n = 26) and neurotypical subjects (n = 26) with their oral hygiene controlled, and the metagenomes of both oral and fecal samples (n = 104) are shotgun-sequenced and compared. We observe extensive and diverse oral phageome comparable to that of the gut, and clear signals of mouth-to-gut phage strain transfer within individuals. However, the overall phageomes of the two sites are widely different and show even less similarity in the oral communities between ASD and control subjects. The ASD oral phageome exhibits significantly reduced abundance and alpha diversity, but the Streptococcal phages there are atypically enriched, often dominating the community. The over-representation of Streptococcal phages is accompanied by enriched oral Streptococcal virulence factors and Streptococcus bacteria, all exhibiting a positive correlation with the severity of ASD clinical manifestations. These changes are not observed in the parallel sampling of the gut flora, suggesting a previously unknown oral-specific association between the excessive Streptococcal phage enrichment and ASD pathogenesis. The findings provide new evidence for the independent microbiome-mouth-brain connection, deepen our understanding of how the growth dynamics of bacteriophages and oral microbiota contribute to ASD, and point to novel effective therapeutics.

Pre-conceptional and prenatal exposure to secondhand smoke and autism spectrum disorder: a national multi-center study in China

BACKGROUND

Despite extensive research evaluating the association between prenatal exposure to secondhand smoke (SHS) and the development of autism spectrum disorders (ASD), no study has investigated the association by considering the pre-conceptional period. This study aimed to investigate the associations of pre-conceptional and prenatal SHS exposure and the development of ASD among toddlers.

METHODS

In this cross-sectional study, parents of 6049 toddlers aged 16-30 months were recruited from 7 tertiary hospitals, 21 communities, and 7 kindergartens located in seven cities in six provinces from five geographical regions of China. We analyzed the associations of SHS exposure and the odds of ASD among toddlers in different exposure windows (pre-conceptional and/or prenatal periods). Data were analyzed from November 2021 to January 2022.

RESULTS

Among the 6049 toddlers included in the analysis [22.7 (4.1) months; 44.8% girls], 71 were identified and diagnosed with ASD. Compared with the unexposed toddlers, toddlers with pre-conceptional SHS exposure had higher odds of ASD (OR 2.30, 95% CI 1.36-3.84), while we observed a non-significantly positive association regarding prenatal SHS exposure. When considering both pre-conceptional and prenatal periods, toddlers who were continuously exposed to SHS during these two periods had higher odds than those without SHS exposure (OR 2.32, 95% CI 1.24-4.14).

CONCLUSION

We reported positive SHS-ASD associations when exposed during the pre-conceptional period and continuously exposed during pre-conceptional and prenatal periods, emphasizing the critical window of pre-conception for targeted intervention on smoking.

Autism Spectrum as an Etiologic Systemic Disorder: A Protocol for an Umbrella Review

Autism spectrum disorder (ASD) is the most common neurodevelopmental disorder with a huge prevalence increasing every year (1/44 children). Still diagnosed as a mental disorder, the last 10 years of research found possible causes, risks, genetics, environmental triggers, epigenetics, metabolic, immunological, and neurophysiological unbalances as relevant aetiology. Umbrella methodology is the highest level of scientific evidence, designed to support clinical and political decisions. A literature search for autism aetiology, pathophysiology, or causes, conducted in the last 10 years, at PubMed, Embase, Cochrane, Scopus, and the Web of Science, resulted in six umbrella reviews. Nevertheless, only one quantitative analysis reported risk factors and biomarkers but excluded genetics, experiments on animal models, and post-mortem studies. We grouped ASD’s multi-factorial causes and risks into five etiological categories: genetic, epigenetic, organic, psychogenic, and environmental. Findings suggest that autism might be evaluated as a systemic disorder instead of only through the lens of mental and behavioural. The overview implications of included studies will be qualitatively analysed under ROBIS and GRADE tools. This umbrella review can provide a rational basis for a new urgent health policy to develop better and adequate integrated care services for ASD. The methodological protocol has the register CRD42022348586 at PROSPERO.

Peripartum effects of synthetic oxytocin: The good, the bad, and the unknown

The first clinical applications of oxytocin (OT) were in obstetrics as a hormone to start and speed up labor and to control postpartum hemorrhage. Discoveries in the 1960s and 1970s revealed that the effects of OT are not limited to its peripheral actions around birth and milk ejection. Indeed, OT also acts as a neuromodulator in the brain affecting fear memory, social attachment, and other forms of social behaviors. The peripheral and central effects of OT have been separately subject to extensive scrutiny. However, the effects of peripheral OT-particularly in the form of administration of synthetic OT (synOT) around birth-on the central nervous system are surprisingly understudied. Here, we provide a narrative review of the current evidence, suggest putative mechanisms of synOT action, and provide new directions and hypotheses for future studies to bridge the gaps between neuroscience, obstetrics, and psychiatry.

Incidence, prevalence, and global burden of autism spectrum disorder from 1990 to 2019 across 204 countries

Autism spectrum disorder (ASD) substantially contributes to the burden of mental disorders. Improved awareness and changes in diagnostic criteria of ASD may have influenced the diagnostic rates of ASD. However, while data on trends in diagnostic rates in some individual countries have been published, updated estimates of diagnostic rate trends and ASD-related disability at the global level are lacking. Here, we used the Global Burden of Diseases, Injuries, and Risk Factors Study data to address this gap, focusing on changes in prevalence, incidence, and disability-adjusted life years (DALYs) of ASD across the world. From 1990 to 2019, overall age-standardized estimates remained stable globally. Both prevalence and DALYs increased in countries with high socio-demographic index (SDI). However, the age-standardized incidence decreased in some low SDI countries, indicating a need to improve awareness. The male/female ratio decreased between 1990 and 2019, possibly accounted for by increasing clinical attention to ASD in females. Our results suggest that ASD detection in low SDI countries is suboptimal, and that ASD prevention/treatment in countries with high SDI should be improved, considering the increasing prevalence of the disorder. Additionally, growing attention is being paid to ASD diagnosis in females, who might have been left behind by ASD epidemiologic and clinical research previously. ASD burden estimates are underestimated as GBD does not account for mortality in ASD.

Modifiable risk factors for incident dementia and cognitive impairment: An umbrella review of evidence

BACKGROUND

Dementia and cognitive impairment can be attributed to genetic and modifiable factors. Considerable evidence emerged in modifiable factors and urgently requires standardized evaluation. We conducted an umbrella review to evaluate the strength and validity of the existing evidence.

METHODS

We searched PubMed, Embase, CINAHL and Cochrane Database of Systematic Reviews to identify relevant systematic reviews and meta-analyses of prospective studies regarding the associations of dementia and cognitive impairment with modifiable factors. For each association, we analyzed the summary effect size, 95 % confidence interval, 95 % prediction interval, heterogeneity, small study effect and excess significance bias. Mendelian randomization studies were descriptively reviewed further exploring the causality of the associations.

RESULTS

In total, 12,015 articles were identified, of which 118 eligible studies yielded 243 unique associations. Convincing evidence was found for associations of dementia and cognitive impairment with early-life education, midlife to late-life plasma glucose, BMI, atrial fibrillation, benzodiazepine use, and gait speed. Suggestive to highly suggestive evidence was found for that of midlife to late-life blood pressure, homocysteine, cerebrovascular diseases, hearing impairment, respiratory illness, anemia, smoking, alcohol consumption, diet, sleep, physical activity and social engagement. Among convincing evidence, Mendelian randomization studies verified causal relationships of education and plasma glucose with Alzheimer's disease.

LIMITATIONS

Low quality of the studies included.

CONCLUSIONS

Modifiable risk factors identified in this study, especially those with high-level evidence, should be considered in dementia prevention. Our results support a valuable rationale for future experimental designs to establish further evidence for the associations in larger populations.

Association between paternal age at childbirth and autism spectrum disorder in offspring

OBJECTIVES

To study the association between paternal age at childbirth and the risk of autism spectrum disorder (ASD) in offspring.

METHODS

In this cross-sectional study, 71 children with ASD who were diagnosed in the Department of Child Healthcare in six hospitals in Guangzhou, Foshan, Beijing, Wuhan, Hangzhou, and Chongqing of China from August 2016 to March 2017 were enrolled as subjects, and 284 typically developing children matched for age, sex, and maternal age at childbirth with the ASD children served as controls. A self-design questionnaire was used to collect the data on social demography, maternal pregnancy, and delivery. The association between paternal age at childbirth and the development of ASD in offspring was evaluated by the logistic regression analysis.

RESULTS

After control for demographic factors and pregnancy- and delivery-related factors, the logistic regression analysis showed that a relatively high paternal age at childbirth was significantly associated with the increased risk of ASD in offspring (OR=1.12, 95%CI: 1.02-1.23, P<0.05). After grouping based on the paternal age, the logistic regression analysis showed that paternal age at childbirth of ≥40 years was significantly associated with the risk of ASD in offspring (before adjustment: OR=7.08, 95%CI: 1.77-28.32, P<0.05; after adjustment: OR=8.50, 95%CI: 1.71-42.25, P<0.05).

CONCLUSIONS

High paternal age at childbirth is significantly associated with the increased risk of ASD in offspring, and paternal age at childbirth ≥40 years may be the high-risk age group for ASD in offspring.

Phosphatidylserine, inflammation, and central nervous system diseases

Phosphatidylserine (PS) is an anionic phospholipid in the eukaryotic membrane and is abundant in the brain. Accumulated studies have revealed that PS is involved in the multiple functions of the brain, such as activation of membrane signaling pathways, neuroinflammation, neurotransmission, and synaptic refinement. Those functions of PS are related to central nervous system (CNS) diseases. In this review, we discuss the metabolism of PS, the anti-inflammation function of PS in the brain; the alterations of PS in different CNS diseases, and the possibility of PS to serve as a therapeutic agent for diseases. Clinical studies have showed that PS has no side effects and is well tolerated. Therefore, PS and PS liposome could be a promising supplementation for these neurodegenerative and neurodevelopmental diseases.

Global population attributable fraction of potentially modifiable risk factors for mental disorders: a meta-umbrella systematic review

Numerous risk factors for mental disorders have been identified. However, we do not know how many disorders we could prevent and to what extent by modifying these risk factors. This study quantifies the Population Attributable Fraction (PAF) of potentially modifiable risk factors for mental disorders. We conducted a PRISMA 2020-compliant (Protocol: https://osf.io/hk2ag ) meta-umbrella systematic review (Web of Science/PubMed/Cochrane Central Register of Reviews/Ovid/PsycINFO, until 05/12/2021) of umbrella reviews reporting associations between potentially modifiable risk factors and ICD/DSM mental disorders, restricted to highly convincing (class I) and convincing (class II) evidence from prospective cohorts. The primary outcome was the global meta-analytical PAF, complemented by sensitivity analyses across different settings, the meta-analytical Generalised Impact Fraction (GIF), and study quality assessment (AMSTAR). Seven umbrella reviews (including 295 meta-analyses and 547 associations) identified 28 class I-II risk associations (23 risk factors; AMSTAR: 45.0% high-, 35.0% medium-, 20.0% low quality). The largest global PAFs not confounded by indication were 37.84% (95% CI = 26.77-48.40%) for childhood adversities and schizophrenia spectrum disorders, 24.76% (95% CI = 13.98-36.49%) for tobacco smoking and opioid use disorders, 17.88% (95% CI = not available) for job strain and depression, 14.60% (95% CI = 9.46-20.52%) for insufficient physical activity and Alzheimer's disease, 13.40% (95% CI = 7.75-20.15%) for childhood sexual abuse and depressive disorders, 12.37% (95% CI = 5.37-25.34%) for clinical high-risk state for psychosis and any non-organic psychotic disorders, 10.00% (95% CI = 5.62-15.95%) for three metabolic factors and depression, 9.73% (95% CI = 4.50-17.30%) for cannabis use and schizophrenia spectrum disorders, and 9.30% (95% CI = 7.36-11.38%) for maternal pre-pregnancy obesity and ADHD. The GIFs confirmed the preventive capacity for these factors. Addressing several potentially modifiable risk factors, particularly childhood adversities, can reduce the global population-level incidence of mental disorders.

Relationships between Women's and Men's Modifiable Preconception Risks and Health Behaviors and Maternal and Offspring Health Outcomes: An Umbrella Review

Parental health before conception effects maternal and offspring health outcomes. Preconception care provides healthcare to prospective parents addressing modifiable preconception risks and health behaviors. This umbrella review aimed to consolidate evidence on women's and men's modifiable preconception risks or health behaviors associated with maternal and offspring health outcomes. MEDLINE, EMBASE, Maternity and Infant Care, CINAHL, and PsycINFO were searched from March 4, 2010, to March 4, 2020. Eligible studies were systematic reviews or meta-analyses of observational studies examining associations between modifiable preconception risks or health behaviors and maternal and offspring health outcomes. Screening, data extraction, and methodological quality assessment (AMSTAR 2) occurred independently by two reviewers. Degree of overlap was examined. Findings were summarized for evidence synthesis. Twenty-seven systematic reviews were included. Modifiable preconception risks and health behaviors were identified across categories: body composition (e.g., overweight, obesity), lifestyle behaviors (e.g., caffeine, smoking), nutrition (e.g., micronutrients), environmental exposures (e.g., radiation), and birth spacing (e.g., short interpregnancy intervals). Outcomes associated with exposures affected embryo (e.g., embryonic growth), maternal (e.g., gestational diabetes mellitus), fetal/neonate (e.g., preterm birth), and child (e.g., neurocognitive disorders) health. For real-world practice and policy relevance, evidence-based indicators for preconception care should include body composition, lifestyle, nutrition, environmental, and birth spacing.

Environmental risk factors, protective factors, and biomarkers for postpartum depressive symptoms: an umbrella review

We performed an umbrella review on environmental risk/protective factors and biomarkers for postpartum depressive symptoms to establish a hierarchy of evidence. We systematically searched PubMed, Embase, and the Cochrane Database of Systematic Reviews from inception until 12 January 2021. We included systematic reviews providing meta-analyses related to our research objectives. Methodological quality was assessed by AMSTAR 2, and the certainty of evidence was evaluated by GRADE. This review was registered in PROSPERO (CRD42021230784). We identified 30 articles, which included 45 environmental risk/protective factors (154,594 cases, 7,302,273 population) and 9 biomarkers (2018 cases, 16,757 population). The credibility of evidence was convincing (class I) for antenatal anxiety (OR 2.49, 1.91-3.25) and psychological violence (OR 1.93, 1.54-2.42); and highly suggestive (class II) for intimate partner violence experience (OR 2.86, 2.12-3.87), intimate partner violence during pregnancy (RR 2.81, 2.11-3.74), smoking during pregnancy (OR 2.39, 1.78-3.2), history of premenstrual syndrome (OR 2.2, 1.81-2.68), any type of violence experience (OR 2.04, 1.72-2.41), primiparity compared to multiparity (RR 1.76, 1.59-1.96), and unintended pregnancy (OR 1.53, 1.35-1.75).

Fecal Microbiota Transplantation and Health Outcomes: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials

Background

Meta-analysis of randomized clinical trials (RCT) demonstrated several health benefits of fecal microbiota transplantation (FMT). However, there has been little comprehensive assessment of the strength and quality of evidence. We conducted an umbrella review to summarize the evidence of the association between FMT and health outcomes.

Methods

PubMed, Embase, and Cochrane library databases were searched from inception to August 6, 2021. The random-effects model was applied to recalculate the effect estimates. We used AMSTAR 2 and GRADE to assess the methodological quality and to grade the evidence.

Results

A total of 7 meta-analyses comprising 26 RCTs (median [IQR] primary study, 6 [2-7]; median [IQR] sample size, 267 [147-431] participants) were included in the current umbrella review describing 45 unique associations. There were 22 statistically significant associations (49%) demonstrating beneficial outcomes of FMT for antibiotic resistance burden, functional constipation, inflammatory bowel disease, and C. difficile infection. FMT does not appear to be associated with positive outcomes in irritable bowel syndrome and metabolic syndrome. Eight significant associations (36%) were supported by moderate-quality evidence, nine associations (41%) were supported by low-quality evidence, and the remaining associations found to be significant were supported by very low-quality evidence.

Conclusion

Although we found that FMT was positively associated with several outcomes, caution should be exercised in choosing this approach, given the insufficient number of primary studies, low methodological quality, and low quality of evidence. Further high-quality randomized controlled trials with long-term follow-up are needed to improve the strength and credibility of the evidence base.

Environmental risk factors for non-Hodgkin's lymphoma: umbrella review and comparison of meta-analyses of summary and individual participant data

Objectives

To summarise the range, strength, and validity of reported associations between environmental risk factors and non-Hodgkin's lymphoma, and to evaluate the concordance between associations reported in meta-analyses of summary level data and meta-analyses of individual participant data.

Design

Umbrella review and comparison of meta-analyses of summary and individual participant level data.

Data sources

Medline, Embase, Scopus, Web of Science Core Collection, Cochrane Library, and Epistemonikos, from inception to 23 July 2021.

Eligibility criteria for selecting studies

English language meta-analyses of summary level data and of individual participant data evaluating associations between environmental risk factors and incident non-Hodgkin's lymphoma (overall and subtypes).

Data extraction and synthesis

Summary effect estimates from meta-analyses of summary level data comparing ever versus never exposure that were adjusted for the largest number of potential confounders were re-estimated using a random effects model and classified as presenting evidence that was non-significant, weak (P<0.05), suggestive (P<0.001 and >1000 cases), highly suggestive (P<0.000001, >1000 cases, largest study reporting a significant association), or convincing (P<0.000001, >1000 cases, largest study reporting a significant association, I2 <50%, 95% prediction interval excluding the null value, and no evidence of small study effects and excess significance bias) evidence. When the same exposures, exposure contrast levels, and outcomes were evaluated in meta-analyses of summary level data and meta-analyses of individual participant data from the International Lymphoma Epidemiology (InterLymph) Consortium, concordance in terms of direction, level of significance, and overlap of 95% confidence intervals was examined. Methodological quality of the meta-analyses of summary level data was assessed by the AMSTAR 2 tool.

Results

We identified 85 meta-analyses of summary level data reporting 257 associations for 134 unique environmental risk factors and 10 subtypes of non-Hodgkin's lymphoma nearly all (79, 93%) were classified as having critically low quality. Most associations (225, 88%) presented either non-significant or weak evidence. The 11 (4%) associations presenting highly suggestive evidence were primarily for autoimmune or infectious disease related risk factors. Only one association, between history of coeliac disease and risk of non-Hodgkin's lymphoma, presented convincing evidence. Of 40 associations reported in meta-analyses of summary level data that were also evaluated in InterLymph meta-analyses of individual participant data, 22 (55%) pairs were in the same direction, had the same level of statistical significance, and had overlapping 95% confidence intervals; 28 (70%) pairs had summary effect sizes from the meta-analyses of individual participant data that were more conservative.

Conclusion

This umbrella review suggests evidence of many meta-analyses of summary level data reporting weak associations between environmental risk factors and non-Hodgkin's lymphoma. Improvements to primary studies as well as evidence synthesis in evaluations of evironmental risk factors and non-Hodgkin's lymphoma are needed.

Review registration number

PROSPERO CRD42020178010.

Genetics of autism spectrum disorder: an umbrella review of systematic reviews and meta-analyses

Autism spectrum disorder (ASD) is a class of neurodevelopmental conditions with a large epidemiological and societal impact worldwide. To date, numerous studies have investigated the associations between genetic variants and ASD risk. To provide a robust synthesis of published evidence of candidate gene studies for ASD, we performed an umbrella review (UR) of meta-analyses of genetic studies for ASD (PROSPERO registration number: CRD42021221868). We systematically searched eight English and Chinese databases from inception to March 31, 2022. Reviewing of eligibility, data extraction, and quality assessment were performed by two authors. In total, 28 of 5062 retrieved articles were analyzed, which investigated a combined 41 single nucleotide polymorphisms (SNPs) of nine candidate genes. Overall, 12 significant SNPs of CNTNAP2, MTHFR, OXTR, SLC25A12, and VDR were identified, of which associations with suggestive evidence included the C677T polymorphism of MTHFR (under allelic, dominant, and heterozygote models) and the rs731236 polymorphism of VDR (under allelic and homozygote models). Associations with weak evidence included the rs2710102 polymorphism of CNTNAP2 (under allelic, homozygote, and recessive models), the rs7794745 polymorphism of CNTNAP2 (under dominant and heterozygote models), the C677T polymorphism of MTHFR (under homozygote model), and the rs731236 polymorphism of VDR (under dominant and recessive models). Our UR summarizes research evidence on the genetics of ASD and provides a broad and detailed overview of risk genes for ASD. The rs2710102 and rs7794745 polymorphisms of CNTNAP2, C677T polymorphism of MTHFR, and rs731236 polymorphism of VDR may confer ASD risks. This study will provide clinicians and healthcare decision-makers with evidence-based information about the most salient candidate genes relevant to ASD and recommendations for future treatment, prevention, and research.

Methodological approaches for assessing certainty of the evidence in umbrella reviews: A scoping review

INTRODUCTION

The number of umbrella reviews (URs) that compiled systematic reviews and meta-analysis (SR-MAs) has increased dramatically over recent years. No formal guidance for assessing the certainty of evidence in URs of meta-analyses exists nowadays. URs of non-interventional studies help establish evidence linking exposure to certain health outcomes in a population. This study aims to identify and describe the methodological approaches for assessing the certainty of the evidence in published URs of non-interventions.

METHODS

We searched from 3 databases including PubMed, Embase, and The Cochrane Library from May 2010 to September 2021. We included URs that included SR-MAs of studies with non-interventions. Two independent reviewers screened and extracted data. We compared URs characteristics stratified by publication year, journal ranking, journal impact factor using Chi-square test.

RESULTS

Ninety-nine URs have been included. Most were SR-MAs of observational studies evaluating association of non-modifiable risk factors with some outcomes. Only half (56.6%) of the included URs assessed the certainty of the evidence. The most frequently used criteria is credibility assessment (80.4%), followed by GRADE approach (14.3%). URs published in journals with higher journal impact factor assessed certainty of evidence than URs published in lower impact group (77.1 versus 37.2% respectively, p < 0.05). However, criteria for credibility assessment used in four of the seven URs that were published in top ranking journals were slightly varied.

CONCLUSIONS

Half of URs of MAs of non-interventional studies have assessed the certainty of the evidence, in which criteria for credibility assessment was the commonly used method. Guidance and standards are required to ensure the methodological rigor and consistency of certainty of evidence assessment for URs.

The epidemiological evidence linking exposure to ambient particulate matter with neurodevelopmental disorders: A systematic review and meta-analysis

BACKGROUND

There has been increasing attention on the associations between ambient particulate matter (PM) in early-life and neurodevelopmental disorders (NDDs). However, the associations remained unclear when considering different types of NDDs and different sizes of PM, and vulnerable exposure windows during early-life were not identified yet.

OBJECTIVE

To synthesize the published literature on the associations between ambient particulate matter (PM) and risk of different types of neurodevelopmental disorders (NDDs) in a systematic review and meta-analysis.

METHODS

A systematic search of Medline, Embase, PubMed, Cochrane Library, and Web of Science was performed from inception through 24 January 2022. Two reviewers conducted the study selection, data extraction, and quality appraisal. A random-effects model was used for meta-analyses with two quality-of-evidence assessments (the Grading of Recommendations Assessment, Development, and Evaluation system and the best evidence synthesis system).

RESULTS

A total of 6554 articles were screened, of which 31 were included in the review, and 20 provided adequate data for meta-analyses. Exposures to particulate matter of 2.5 μm or less (PM_2.5) during prenatal periods (OR, 1.32 [95%CI, 1.03-1.69]), the first year after birth (OR, 1.62 [95%CI, 1.22-2.15]) and the second year after birth (OR, 3.13 [95%CI, 1.47-6.67]) were associated with increased risk of autism spectrum disorders (ASD) in children. The quality of evidence for these associations during early postnatal periods was somewhat moderate with limited studies. We found inconsistent evidence when considering other types of NDDs and different sizes of PM.

CONCLUSIONS AND RELEVANCE

Current evidence indicated that there might be an association between PM_2.5 exposure and higher risk of ASD, and early postnatal periods appeared to be the critical exposure window. High-quality studies are needed to assess the evidence for other types of NDDs.

[Early prognostic of ASD: A challenge]

Autism Spectrum Disorders (ASD) are born in the womb generated by intrauterine genetic or environmental insult. ASD diagnostic is made at the age of 3-5 years in Europe and in the US. Relying on this, we have tested the hypothesis of identifying already at birth babies who might be diagnosed later with ASD, thereby facilitating an early use of psychoeducative techniques to attenuate the severity of the symptoms. Here, we discuss the various approaches that have been used to enable an early diagnosis. We have ourselves used an approach based on a "without a priori" machine learning analysis of all maternity biological and ultrasound data available in French maternities (around 116) in utero and after birth. This program made it possible to identify at birth almost all (96%) of babies who will be later neurotypical and around half of those who will be diagnosed with ASD. Some of the parameters allowing this identification were largely unexpected with no known links with ASD. This approach will enable an early identification of babies at risk, but also might be used to diagnose ASD later on, and perhaps could help to get a better understanding of the heterogeneity of ASD.

Molecular Alterations of the Endocannabinoid System in Psychiatric Disorders

The therapeutic benefits of the current medications for patients with psychiatric disorders contrast with a great variety of adverse effects. The endocannabinoid system (ECS) components have gained high interest as potential new targets for treating psychiatry diseases because of their neuromodulator role, which is essential to understanding the regulation of many brain functions. This article reviewed the molecular alterations in ECS occurring in different psychiatric conditions. The methods used to identify alterations in the ECS were also described. We used a translational approach. The animal models reproducing some behavioral and/or neurochemical aspects of psychiatric disorders and the molecular alterations in clinical studies in post-mortem brain tissue or peripheral tissues were analyzed. This article reviewed the most relevant ECS changes in prevalent psychiatric diseases such as mood disorders, schizophrenia, autism, attentional deficit, eating disorders (ED), and addiction. The review concludes that clinical research studies are urgently needed for two different purposes: (1) To identify alterations of the ECS components potentially useful as new biomarkers relating to a specific disease or condition, and (2) to design new therapeutic targets based on the specific alterations found to improve the pharmacological treatment in psychiatry.

The environmental risk factors prior to conception associated with placental abruption: an umbrella review

BACKGROUND

The present umbrella review evaluated risk factors prior to conception associated with placental abruption based on meta-analyses and systematic reviews.

METHODS

We searched PubMed, Scopus, and Web of Science until June 25, 2021. All meta-analyses that had focused on assessing the risk factors associated with placental abruption were included. We calculated summary effect estimates, 95% CI, heterogeneity I², 95% prediction interval, small-study effects, excess significance biases, and sensitive analysis. The quality of the meta-analyses was evaluated with A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2).

RESULTS

There was no risk factor in the present umbrella review with the high level of evidence (class I or II). Eight risk factors including maternal asthma (RR 1.29 95% CI 1.14, 1.47), prior cesarean section (RR 1.38, 95% CI 1.35-1.42), cocaine using (RR 4.55, 95% CI 1.78-6.50), endometriosis (OR 1.40, 95% CI 1.12-1.76), chronic hypertension (OR 3.13, 95% CI 2.04-4.80), advanced maternal age (OR 1.44, 95% CI 1.35-1.54), maternal smoking (OR 1.80, 95% CI 1.75-1.85) (RR 1.65, 95% CI 1.51-1.80), and use of assisted reproductive techniques (ART) (OR 1.87, 95% CI 1.70-2.06) were graded as suggestive evidence (class III). The other four risk factors including pre-pregnancy underweight (OR 1.38, 95% CI 1.12-1.70), preeclampsia (OR 1.73, 95% CI 1.47-2.04), uterine leiomyoma (OR 2.63, 95% CI 1.38-3.88), and marijuana use (OR 1.78, 95% CI 1.32-2.40) were graded as risk factors with weak evidence (class IV).

CONCLUSION

Maternal asthma, prior cesarean section, cocaine use, endometriosis, chronic hypertension, advanced maternal age, maternal smoking, and use of ART, pre-pregnancy underweight, preeclampsia, uterine leiomyoma, and marijuana use were risk factors associated with placental abruption. Although factors associated with placental abruption have been investigated, the current meta-analytic associations cannot disentangle the complex etiology of placental abruption mainly due to their low quality of evidence.

Autism Spectrum Disorder: Focus on Glutamatergic Neurotransmission

Disturbances in the glutamatergic system have been increasingly documented in several neuropsychiatric disorders, including autism spectrum disorder (ASD). Glutamate-centered theories of ASD are based on evidence from patient samples and postmortem studies, as well as from studies documenting abnormalities in glutamatergic gene expression and metabolic pathways, including changes in the gut microbiota glutamate metabolism in patients with ASD. In addition, preclinical studies on animal models have demonstrated glutamatergic neurotransmission deficits and altered expression of glutamate synaptic proteins. At present, there are no approved glutamatergic drugs for ASD, but several ongoing clinical trials are currently focusing on evaluating in autistic patients glutamatergic pharmaceuticals already approved for other conditions. In this review, we provide an overview of the literature concerning the role of glutamatergic neurotransmission in the pathophysiology of ASD and as a potential target for novel treatments.

The Synaptic Gene Study: Design and Methodology to Identify Neurocognitive Markers in Phelan-McDermid Syndrome and NRXN1 Deletions

Synaptic gene conditions, i.e., “synaptopathies,” involve disruption to genes expressed at the synapse and account for between 0.5 and 2% of autism cases. They provide a unique entry point to understanding the molecular and biological mechanisms underpinning autism-related phenotypes. Phelan-McDermid Syndrome (PMS, also known as 22q13 deletion syndrome) and NRXN1 deletions (NRXN1ds) are two synaptopathies associated with autism and related neurodevelopmental disorders (NDDs). PMS often incorporates disruption to the SHANK3 gene, implicated in excitatory postsynaptic scaffolding, whereas the NRXN1 gene encodes neurexin-1, a presynaptic cell adhesion protein; both are implicated in trans-synaptic signaling in the brain. Around 70% of individuals with PMS and 43–70% of those with NRXN1ds receive a diagnosis of autism, suggesting that alterations in synaptic development may play a crucial role in explaining the aetiology of autism. However, a substantial amount of heterogeneity exists between conditions. Most individuals with PMS have moderate to profound intellectual disability (ID), while those with NRXN1ds have no ID to severe ID. Speech abnormalities are common to both, although appear more severe in PMS. Very little is currently known about the neurocognitive underpinnings of phenotypic presentations in PMS and NRXN1ds. The Synaptic Gene (SynaG) study adopts a gene-first approach and comprehensively assesses these two syndromic forms of autism. The study compliments preclinical efforts within AIMS-2-TRIALS focused on SHANK3 and NRXN1. The aims of the study are to (1) establish the frequency of autism diagnosis and features in individuals with PMS and NRXN1ds, (2) to compare the clinical profile of PMS, NRXN1ds, and individuals with ‘idiopathic’ autism (iASD), (3) to identify mechanistic biomarkers that may account for autistic features and/or heterogeneity in clinical profiles, and (4) investigate the impact of second or multiple genetic hits on heterogeneity in clinical profiles. In the current paper we describe our methodology for phenotyping the sample and our planned comparisons, with information on the necessary adaptations made during the global COVID-19 pandemic. We also describe the demographics of the data collected thus far, including 25 PMS, 36 NRXN1ds, 33 iASD, and 52 NTD participants, and present an interim analysis of autistic features and adaptive functioning.

Dysregulated Nrf2 signaling in response to di(2-ethylhexyl) phthalate in neutrophils of children with autism

Autism spectrum disorder (ASD) is characterized by constellation of impaired behaviors that include deficits in social interaction/communication and the presence of restricted/repetitive behavioral patterns. Both genetic component and environmental factors are thought to play a key role in the initiation and progression of ASD. Several environmental factors such as heavy metals and plasticizers are known to affect the progression of ASD. One of the most common pollutants in the environment today is di-2-ethylhexyl phthalate (DEHP). DEHP is utilized as a plasticizer in several household and office materials which range from medical devices to plastic toys. Children usually get exposed to DEHP at an early age through use of plastic toys and other plastic materials. Nuclear factor erythroid 2 (NFE2)-relatedfactor-2 (Nrf2) is a master redox regulator as it controls transcription of several antioxidant genes. DEHP has been reported to cause dysregulation in Nrf2 signaling in vitro/in vivo and ASD subjects also exhibit oxidant-antioxidant imbalance.Therefore, this study attempted to delineate the effect of DEHP on Nrf2 signaling in neutrophils of ASD and typically developing healthy children (TDC) in vitro. Our data display that neutrophils of ASD subjects have dysregulated Nrf2 and hemeoxygenase-1 (HO-1) expression as compared to TDC subjects. DEHP treatment leads to elevation of oxidant stress in neutrophils of both ASD and TDC subjects, however TDC neutrophils have better antioxidant response to mitigate oxidative stress. This is depicted by enhancement of Nrf2/HO-1 signaling in TDC neutrophils in response to DEHP whereas ASD neutrophils fail to do so. These results suggest that plasticizer, DEHP may cause further dysregulation in Nrf2 signaling which may promote progression of ASD.

Correlation among gut microbiota, fecal metabolites and autism-like behavior in an adolescent valproic acid-induced rat autism model

This study aims to understand the relationship between fecal metabolites and gut microbiota in an adolescent valproic acid-induced rat autism model (VPA-exposed offspring). We analyzed the fecal samples of VPA-exposed offspring using 16S rRNA gene sequencing and untargeted metabolomics. Autism-like behavior was evaluated by a three-chamber sociability test and a self-grooming test. Based on these data, we analyzed the association among fecal metabolites, gut microbiota and autism-like behavior. Behavioral tests showed that VPA-exposed offspring displayed typical autism-like behavior. Forty-nine named differential fecal metabolites and 14 enriched KEGG pathways were identified between the VPA and control groups. Five fecal metabolites may be used as characteristic metabolites. The richness and diversity of gut microbiota did not differ between the two groups, while the overall composition of gut microbiota was significantly different. Candidatus_Saccharimonas, Desulfovibrio, [Eubacterium]_xylanophilum_group and Ruminococcus_2 were the characteristic genera of VPA-exposed offspring. Correlation analysis revealed a tight relationship among gut microbiota, fecal metabolites and autistic behavior in VPA-exposed offspring. This study illustrates that specific alterations in gut microbiota and fecal metabolites may be regarded as characteristics of VPA-exposed offspring. The characteristic gut microbiota and fecal metabolites as well as their relationship may play a crucial role in autism-like behavior caused by prenatal exposure to VPA.

Early life environmental factors associated with autism spectrum disorder symptoms in children at age 2 years: A birth cohort study

LAY ABSTRACT

Mounting evidence indicates the contribution of early life environmental factors in autism spectrum disorder. We aim to report the prospective associations between early life environmental factors and autism spectrum disorder symptoms in children at the age of 2 years in a population-derived birth cohort, the Barwon Infant Study. Autism spectrum disorder symptoms at the age of 2 years strongly predicted autism spectrum disorder diagnosis by the age of 4 years (area under curve = 0.93; 95% CI (0.82, 1.00)). After adjusting for child's sex and age at the time of behavioural assessment, markers of socioeconomic disadvantage, such as lower household income and lone parental status; maternal health factors, including younger maternal age, maternal pre-pregnancy body mass index, higher gestational weight gain and prenatal maternal stress; maternal lifestyle factors, such as prenatal alcohol and environmental air pollutant exposures, including particulate matter < 2.5 μm at birth, child secondhand tobacco smoke at 12 months, dampness/mould and home heating with oil, kerosene or diesel heaters at 2 years postnatal. Lower socioeconomic indexes for area, later birth order, higher maternal prenatal depression and maternal smoking frequency had a dose-response relationship with autism spectrum disorder symptoms. Future studies on environmental factors and autism spectrum disorder should consider the reasons for the socioeconomic disparity and the combined impact of multiple environmental factors through common mechanistic pathways.

Influence of Prenatal Drug Exposure, Maternal Inflammation, and Parental Aging on the Development of Autism Spectrum Disorder

Autism spectrum disorder (ASD) affects reciprocal social interaction and produces abnormal repetitive, restrictive behaviors and interests. The diverse causes of ASD are divided into genetic alterations and environmental risks. The prevalence of ASD has been rising for several decades, which might be related to environmental risks as it is difficult to consider that the prevalence of genetic disorders related to ASD would increase suddenly. The latter includes (1) exposure to medications, such as valproic acid (VPA) and selective serotonin reuptake inhibitors (SSRIs) (2), maternal complications during pregnancy, including infection and hypertensive disorders of pregnancy, and (3) high parental age. Epidemiological studies have indicated a pathogenetic role of prenatal exposure to VPA and maternal inflammation in the development of ASD. VPA is considered to exert its deleterious effects on the fetal brain through several distinct mechanisms, such as alterations of γ-aminobutyric acid signaling, the inhibition of histone deacetylase, the disruption of folic acid metabolism, and the activation of mammalian target of rapamycin. Maternal inflammation that is caused by different stimuli converges on a higher load of proinflammatory cytokines in the fetal brain. Rodent models of maternal exposure to SSRIs generate ASD-like behavior in offspring, but clinical correlations with these preclinical findings are inconclusive. Hypertensive disorders of pregnancy and advanced parental age increase the risk of ASD in humans, but the mechanisms have been poorly investigated in animal models. Evidence of the mechanisms by which environmental factors are related to ASD is discussed, which may contribute to the development of preventive and therapeutic interventions for ASD.

OUP accepted manuscript

Mesenchymal stem cell-based therapy has emerged as a great potential approach to treat individuals with autism spectrum disorders (ASD), a group of developmental disabilities characterized by impairments in social interaction and communication. Stem cells from human exfoliated deciduous teeth (SHED), holding earlier developing characteristics, have immune-modulatory and anti-inflammatory properties. To investigate whether SHED transplantation can rescue autistic-like symptoms in SHANK3 mutant beagle dogs, 12 SHANK3 mutant beagle dogs were randomly assigned into 2 groups according to their behavior evaluated by social interaction tests. Six mutant dogs received 6 intravenous infusions of SHED and were followed up for 3 months by testing social interaction and inflammatory cytokine levels. We found that infusion of SHED significantly improved impaired social novel preference of SHANK3 mutant beagle dogs at 1- and 3-month follow-ups. Social intimacies (following, sniffing, and licking) between mutant beagle dogs and human experimenters were partly improved. Stressed tail posture, indicating social stress, was also significantly alleviated. In addition, we showed that the levels of serum interferon-γ and interleukin-10 were notably increased and decreased, respectively, in SHANK3 mutant beagle dogs. Infusion of SHED was able to rescue altered interferon-γ and interleukin-10 levels. We failed to observe any serious adverse events after infusion of SHED. In summary, SHED transplantation may be a safe and effective therapy for ASD. The correction in the levels of serum interferon-γ and interleukin-10 may serve as an index to predict autistic severity and therapeutic outcomes.

Labor epidural analgesia and risk of autism Spectrum disorders in offspring: A systematic review and meta-analysis

Background

The effect of labor epidural anesthesia (LEA) on the risk of autism spectrum disorder (ASD) in offspring has been investigated recently, and available results are inconsistent.

Methods

We searched the PubMed and EMBASE databases for relevant studies and performed a systematic review and meta-analysis of the literature. Subgroup analyses were conducted to assess the sources of heterogeneity. Both fixed and random effects models were used was used to estimate overall relative risk.

Results

Our results showed that LEA was associated with an increased risk of ASD in offspring [HR = 1.3, 95% confidence interval (CI): 1.25-1.35; P < 0.001] after combining crude estimates from the included studies. This association was gradually reduced, but still statistically significant, when potential confounding factors were considered (HR 1.13, 95% CI 1.03-1.25, P = 0.014). However, there was no significant association when we combined data of siblings from other pregnancies (HR = 1.07, 95% CI: 0.99-1.16, P = 0.076), implying that the association was due to confounding factors.

Conclusion

The statistically significant association between LEA and ASD in the offspring can be partially explained by unmeasured confounding.

Systematic Review Registration

Identifier CRD42022302892.

Age at onset of mental disorders worldwide: large-scale meta-analysis of 192 epidemiological studies

Promotion of good mental health, prevention, and early intervention before/at the onset of mental disorders improve outcomes. However, the range and peak ages at onset for mental disorders are not fully established. To provide robust, global epidemiological estimates of age at onset for mental disorders, we conducted a PRISMA/MOOSE-compliant systematic review with meta-analysis of birth cohort/cross-sectional/cohort studies, representative of the general population, reporting age at onset for any ICD/DSM-mental disorders, identified in PubMed/Web of Science (up to 16/05/2020) (PROSPERO:CRD42019143015). Co-primary outcomes were the proportion of individuals with onset of mental disorders before age 14, 18, 25, and peak age at onset, for any mental disorder and across International Classification of Diseases 11 diagnostic blocks. Median age at onset of specific disorders was additionally investigated. Across 192 studies (n = 708,561) included, the proportion of individuals with onset of any mental disorders before the ages of 14, 18, 25 were 34.6%, 48.4%, 62.5%, and peak age was 14.5 years (k = 14, median = 18, interquartile range (IQR) = 11-34). For diagnostic blocks, the proportion of individuals with onset of disorder before the age of 14, 18, 25 and peak age were as follows: neurodevelopmental disorders: 61.5%, 83.2%, 95.8%, 5.5 years (k = 21, median=12, IQR = 7-16), anxiety/fear-related disorders: 38.1%, 51.8%, 73.3%, 5.5 years (k = 73, median = 17, IQR = 9-25), obsessive-compulsive/related disorders: 24.6%, 45.1%, 64.0%, 14.5 years (k = 20, median = 19, IQR = 14-29), feeding/eating disorders/problems: 15.8%, 48.1%, 82.4%, 15.5 years (k = 11, median = 18, IQR = 15-23), conditions specifically associated with stress disorders: 16.9%, 27.6%, 43.1%, 15.5 years (k = 16, median = 30, IQR = 17-48), substance use disorders/addictive behaviours: 2.9%, 15.2%, 48.8%, 19.5 years (k = 58, median = 25, IQR = 20-41), schizophrenia-spectrum disorders/primary psychotic states: 3%, 12.3%, 47.8%, 20.5 years (k = 36, median = 25, IQR = 20-34), personality disorders/related traits: 1.9%, 9.6%, 47.7%, 20.5 years (k = 6, median = 25, IQR = 20-33), and mood disorders: 2.5%, 11.5%, 34.5%, 20.5 years (k = 79, median = 31, IQR = 21-46). No significant difference emerged by sex, or definition of age of onset. Median age at onset for specific mental disorders mapped on a time continuum, from phobias/separation anxiety/autism spectrum disorder/attention deficit hyperactivity disorder/social anxiety (8-13 years) to anorexia nervosa/bulimia nervosa/obsessive-compulsive/binge eating/cannabis use disorders (17-22 years), followed by schizophrenia, personality, panic and alcohol use disorders (25-27 years), and finally post-traumatic/depressive/generalized anxiety/bipolar/acute and transient psychotic disorders (30-35 years), with overlap among groups and no significant clustering. These results inform the timing of good mental health promotion/preventive/early intervention, updating the current mental health system structured around a child/adult service schism at age 18.

Efficacy of psychosocial interventions for Autism spectrum disorder: an umbrella review

INTRODUCTION

The wide range of psychosocial interventions designed to assist people with Autism Spectrum Disorder (ASD) makes it challenging to compile and hierarchize the scientific evidence that supports the efficacy of these interventions. Thus, we performed an umbrella review of published meta-analyses of controlled clinical trials that investigated the efficacy of psychosocial interventions on both core and related ASD symptoms.

METHODS

Each meta-analysis that was identified was re-estimated using a random-effects model with a restricted maximum likelihood estimator. The methodological quality of included meta-analyses was critically appraised and the credibility of the evidence was assessed algorithmically according to criteria adapted for the purpose of this study.

RESULTS

We identified a total of 128 meta-analyses derived from 44 reports. More than half of the non-overlapping meta-analyses were nominally statistically significant and/or displayed a moderate-to-large pooled effect size that favored the psychosocial interventions. The assessment of the credibility of evidence pointed out that the efficacy of early intensive behavioral interventions, developmental interventions, naturalistic developmental behavioral interventions, and parent-mediated interventions was supported by suggestive evidence on at least one outcome in preschool children. Possible outcomes included social communication deficits, global cognitive abilities, and adaptive behaviors. Results also revealed highly suggestive indications that parent-mediated interventions improved disruptive behaviors in early school-aged children. The efficacy of social skills groups was supported by suggestive evidence for improving social communication deficits and overall ASD symptoms in school-aged children and adolescents. Only four meta-analyses had a statistically significant pooled effect size in a sensitivity analysis restricted to randomized controlled trials at low risk of detection bias.

DISCUSSION

This umbrella review confirmed that several psychosocial interventions show promise for improving symptoms related to ASD at different stages of life. However, additional well-designed randomized controlled trials are still required to produce a clearer picture of the efficacy of these interventions. To facilitate the dissemination of scientific knowledge about psychosocial interventions for individuals with ASD, we built an open-access and interactive website that shares the information collected and the results generated during this umbrella review.

PRE-REGISTRATION

PROSPERO ID CRD42020212630.

The Role of Vitamin D Supplementation in Children with Autism Spectrum Disorder: A Narrative Review

Children with autism spectrum disorder (ASD) present with persistent deficits in both social communication and interactions, along with the presence of restricted and repetitive behaviors, resulting in significant impairment in significant areas of functioning. Children with ASD consistently reported significantly lower vitamin D levels than typically developing children. Moreover, vitamin D deficiency was found to be strongly correlated with ASD severity. Theoretically, vitamin D can affect neurodevelopment in children with ASD through its anti-inflammatory properties, stimulating the production of neurotrophins, decreasing the risk of seizures, and regulating glutathione and serotonin levels. A Title/Abstract specific search for publications on Vitamin D supplementation trials up to June 2021 was performed using two databases: PubMed and Cochrane Library. Twelve experimental studies were included in the synthesis of this review. Children with ASD reported a high prevalence of vitamin D deficiency or insufficiency. In general, it was observed that improved vitamin D status significantly reduced the ASD severity, however, this effect was not consistently different between the treatment and control groups. The variations in vitamin D dose protocols and the presence of concurrent interventions might provide an explanation for the variability of results. The age of the child for introducing vitamin D intervention was identified as a possible factor determining the effectiveness of the treatment. Common limitations included a small number of participants and a short duration of follow-ups in the selected studies. Long-term, well-designed randomized controlled trials are warranted to confirm the effect of vitamin D on severity in children with ASD.

Association of phthalate exposure with autistic traits in children

BACKGROUND

Phthalates are synthetic chemicals with endocrine-disrupting properties. They are reportedly associated with various neurotoxic outcomes. Studies on exposure to phthalates and children's autistic traits have shown inconsistent results with respect to sex and susceptible time periods. We investigated the association of phthalate exposure during the prenatal period and childhood with autistic traits over time using a birth cohort in South Korea.

METHODS

Five phthalate metabolites were measured during mid-term pregnancy and children's follow-up at ages of 4, 6, and 8 years among a total of 547 mother-child pairs. The social communication questionnaire (SCQ) was used to assess autistic traits of children at each time point. The relationship between phthalate metabolites and SCQ scores were analyzed by exposure windows and sex.

RESULTS

A 2.7 fold increase in di-(2-ethylhexyl) phthalate metabolite levels, mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) during pregnancy was associated with increased SCQ scores at 4 years by 8.5% (95% confidence intervals [CI]: 1.9%, 15.5%) and 7.4% (95% CI: 0.3%, 15.0%), respectively, but not at the age of 6 or 8 years. Moreover, MEHHP levels at ages of 4 and 8 years were associated with increased SCQ scores at 8 years by 9.9% (95% CI: 1.8%, 18.6%) and 9.6% (95% CI: 1.3%, 18.6%), respectively. Boys showed stronger associations between phthalate exposure and SCQ scores than girls.

CONCLUSION

The study suggested different susceptible time windows of phthalate exposure: exposure during pregnancy is associated with autistic traits in young children, whereas exposure during early childhood years leads to autistic traits in school-aged children, particularly boys.

Endocannabinoid markers in autism spectrum disorder: A scoping review of human studies

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication deficits and patterns of restrictive and repetitive behavior. Although the neurological underpinnings of ASD remain elusive, the endocannabinoid system (ECS) may play a role in modulating social behavior in ASD. Preclinical studies have suggested that alterations in the ECS result in ASD-like phenotypes, but currently no reviews have examined ECS abnormalities in human studies. This scoping review investigated any evidence of ECS alterations in humans with ASD. A comprehensive literature search was conducted and five studies were eligible for review. Three studies reported a significant reduction of anandamide in ASD compared to controls. Other alterations included decreased 2-arachidonoylglycerol, oleoylethanolamide, and palmitoylethanolamide and elevated diacylglycerol lipase and monoacylglycerol lipase. Some discrepant findings were also noted, which included elevated or reduced CB2 receptor in three studies and elevated or reduced N-acyl phosphatidylethanolamine phospholipase D and fatty acid amide hydrolase in two studies. We conclude from this preliminary investigation that the ECS may be altered in humans with ASD. Potential limitations of the reviewed studies include medication use and psychiatric comorbidities. Further research, such as positron emission tomography studies, are necessary to fully understand the relationship between ECS markers and ASD.

Environmental Risk Factors for Endometriosis: An Umbrella Review of a Meta-Analysis of 354 Observational Studies With Over 5 Million Populations

Background: The association between a diverse array of environmental risk factors and the risk of endometriosis is contradictory. Objective: To summarize the evidence of associations between environmental risk factors and the risk of endometriosis. Methods: Databases such as PubMed, EMBASE, Web of Science, and ClinicalTrial.gov were systematically searched in June 2020. Meta-analyses of observational studies investigated any environmental exposure (non-genetic) and endometriosis risk. For each article, we estimated the summary effect size, 95% CIs, and the 95% prediction interval (PI). We also estimated the between-study heterogeneity expressed by I ², evidence for small-study effects, and evidence of excess significance bias. Results: About 12 eligible articles (featuring 143,422 cases and 5,112,967 participants) yielded data on 40 unique environmental risk factors, including life styles (n = 16), reproductive factors (n = 3), early life factors (n = 4), and a range of other risk factors [e.g., phthalate metabolites, endocrine-disrupting chemicals, and body mass index (BMI)]. About 25 of these 40 associations (62.5%) were statistically significant (p < 0.05) under random-effects models. Evidence for an association was indicated for alcohol intake [relative risk (RR): 1.25; 95% CI: 1.11-1.41] and the exposure to endocrine disruptor chemicals (EDCs) (RR: 1.41; 95% CI: 1.23-1.60) while 15 associations presented only weak evidence. Conclusions: Our analyses showed that alcohol intake and exposure to endocrine-disrupting chemicals may be potential risk factors for endometriosis and supported by suggestive epidemiological evidence. However, it was evident that there was substantial heterogeneity and/or bias between the different studies featured in various meta-analyses included in this review; therefore, the outcomes of our analysis should be interpreted cautiously.

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.

The risk factors associated with placenta previa: An umbrella review

We evaluated in this umbrella review a systematic collection from meta-analyses conducted on risk factors associated with placenta previa. We searched PubMed, Scopus, and Web of Science until April 2021 assessing the risk factors associated with placenta previa. We calculated summary effect estimates odds ratio, relative risk, 95% CI, heterogeneity I², 95% prediction interval, small-study effects, excess significance biases, and sensitive analysis. The quality of the meta-analyses was evaluated with AMSTAR 2. We included nine studies in the present umbrella review. Seven risk factors including prior induced abortion (OR 1·36, 95% CI: 1·02, 1·69), prior spontaneous abortion (OR 1·77, 95% CI: 1·60, 1·94), male fetus (OR 1·2, 95% CI: 1·2, 1·3), smoking (OR 1·42, 95% CI 1·30, 1·54) (RR 1·27, 95% CI: 1·18, 1·35) advanced maternal age (OR 3·16, 95% CI: 2·79, 3·57), cesarean (OR 1·60, 95% CI: 1·44, 1·76) and ART (singleton pregnancy) (RR 3·71, 95% CI: 2·67, 5·16) were graded as highly suggestive evidence (class III). Endometriosis (OR 3·03, 95% CI: 1·50, 6·13) and maternal cocaine use (OR 2·9, 95% CI: 1·9, 4·3) were graded as risk factors with weak evidence (class IV). This study provides suggestive evidence about prior spontaneous abortion, prior induced abortion, male fetus, smoking, advanced maternal age, cesarean section, and assisted reproductive techniques (singleton pregnancy) as risk factors associated with placenta previa.

Associations of Nutritional, Lifestyle, and Metabolic Factors With Non-alcoholic Fatty Liver Disease: An Umbrella Review With More Than 380,000 Participants

Background & Aims: Nonalcoholic fatty liver disease (NAFLD) is the most common liver injury. We performed this umbrella review of meta-analyses to summarize the evidence on the associations of nutritional, lifestyle, and metabolic factors with NAFLD.

Methods: We searched the PubMed, Embase, and Web of Science databases from inception until July 2, 2020, to identify meta-analyses of observational studies which explored the associations of nutritional, lifestyle, and metabolic factors with NAFLD. Evidence levels were assessed using summary effect sizes, 95% prediction intervals, between-study heterogeneity, evidence of small-study effects, and evidence of excess significance bias for each meta-analysis. (No. of PROSPERO, CRD42020200124).

Results: Twenty two risk or protective factors from 10 published meta-analyses were included and studied. Three risk factors (sugar-sweetened beverage consumption, serum fetuin-A, and waist circumference) with highly suggestive levels of evidence and three risk factors (soft drink consumption, former smoking, and body mass index) with suggestive levels of evidence were identified. Only two protective factors (physical activity and serum vitamin D level [among adults in Western countries]) with suggestive levels of evidence were identified. Furthermore, other six risk factors and two protective factors with weak levels of evidence were identified.

Conclusions: We found varying levels of evidence of associations of nutritional, lifestyle, and metabolic factors and NAFLD. The results suggest that nutritional and lifestyle management should be considered as a major primary preventive strategy for NAFLD. Moreover, considering the low quality of included meta-analyses and limited area of research topics, future high-quality original studies and meta-analyses should be performed to study these associations.

Risk and protective factors for mental disorders beyond genetics: an evidence-based atlas

Decades of research have revealed numerous risk factors for mental disorders beyond genetics, but their consistency and magnitude remain uncer-tain. We conducted a "meta-umbrella" systematic synthesis of umbrella reviews, which are systematic reviews of meta-analyses of individual studies, by searching international databases from inception to January 1, 2021. We included umbrella reviews on non-purely genetic risk or protective factors for any ICD/DSM mental disorders, applying an established classification of the credibility of the evidence: class I (convincing), class II (highly suggestive), class III (suggestive), class IV (weak). Sensitivity analyses were conducted on prospective studies to test for temporality (reverse causation), TRANSD criteria were applied to test transdiagnosticity of factors, and A Measurement Tool to Assess Systematic Reviews (AMSTAR) was employed to address the quality of meta-analyses. Fourteen eligible umbrella reviews were retrieved, summarizing 390 meta-analyses and 1,180 associations between putative risk or protective factors and mental disorders. We included 176 class I to III evidence associations, relating to 142 risk/protective factors. The most robust risk factors (class I or II, from prospective designs) were 21. For dementia, they included type 2 diabetes mellitus (risk ratio, RR from 1.54 to 2.28), depression (RR from 1.65 to 1.99) and low frequency of social contacts (RR=1.57). For opioid use disorders, the most robust risk factor was tobacco smoking (odds ratio, OR=3.07). For non-organic psychotic disorders, the most robust risk factors were clinical high risk state for psychosis (OR=9.32), cannabis use (OR=3.90), and childhood adversities (OR=2.80). For depressive disorders, they were widowhood (RR=5.59), sexual dysfunction (OR=2.71), three (OR=1.99) or four-five (OR=2.06) metabolic factors, childhood physical (OR=1.98) and sexual (OR=2.42) abuse, job strain (OR=1.77), obesity (OR=1.35), and sleep disturbances (RR=1.92). For autism spectrum disorder, the most robust risk factor was maternal overweight pre/during pregnancy (RR=1.28). For attention-deficit/hyperactivity disorder (ADHD), they were maternal pre-pregnancy obesity (OR=1.63), maternal smoking during pregnancy (OR=1.60), and maternal overweight pre/during pregnancy (OR=1.28). Only one robust protective factor was detected: high physical activity (hazard ratio, HR=0.62) for Alzheimer's disease. In all, 32.9% of the associations were of high quality, 48.9% of medium quality, and 18.2% of low quality. Transdiagnostic class I-III risk/protective factors were mostly involved in the early neurodevelopmental period. The evidence-based atlas of key risk and protective factors identified in this study represents a benchmark for advancing clinical characterization and research, and for expanding early intervention and preventive strategies for mental disorders.