Association of maternal autoimmune disease and early childhood infections with offspring autism spectrum disorder: A population-based cohort study

Autism spectrum disorders and the gastrointestinal tract: insights into mechanisms and clinical relevance

Autism spectrum disorders (ASDs) are recognized as central neurodevelopmental disorders diagnosed by impairments in social interactions, communication and repetitive behaviours. The recognition of ASD as a central nervous system (CNS)-mediated neurobehavioural disorder has led most of the research in ASD to be focused on the CNS. However, gastrointestinal function is also likely to be affected owing to the neural mechanistic nature of ASD and the nervous system in the gastrointestinal tract (enteric nervous system). Thus, it is unsurprising that gastrointestinal disorders, particularly constipation, diarrhoea and abdominal pain, are highly comorbid in individuals with ASD. Gastrointestinal problems have also been repeatedly associated with increased severity of the core symptoms diagnostic of ASD and other centrally mediated comorbid conditions, including psychiatric issues, irritability, rigid-compulsive behaviours and aggression. Despite the high prevalence of gastrointestinal dysfunction in ASD and its associated behavioural comorbidities, the specific links between these two conditions have not been clearly delineated, and current data linking ASD to gastrointestinal dysfunction have not been extensively reviewed. This Review outlines the established and emerging clinical and preclinical evidence that emphasizes the gut as a novel mechanistic and potential therapeutic target for individuals with ASD.

Correlation analysis of maternal condition during pregnancy with head circumference and autism spectrum disorder: A propensity score-matched study

To determine whether health status during pregnancy is associated with autism spectrum disorder (ASD) and abnormal head circumference (HC) in the offspring. This study included 41 Han children with ASD who visited the Children's Health Clinic of the Second Hospital of Shandong University between March 2018 and February 2019, and 264 Han children with typical development (TD) who visited the clinic during the same period. Physical measurements were performed on the children. The questionnaire obtained information on maternal risk factors that may be related to the increased risk of ASD and folic acid (FA) supplementation. We designed an observational case-control study using propensity score matching and multivariate logistic regression analysis. The incidence of macrocephaly in the ASD group was 22.0%, significantly higher than that in the TD group (1.8%). The incidence of microcephaly in the ASD group was 17.1% (n = 7), significantly higher than that in the TD group (1.8%). The differences between the comparisons were statistically significant. Maternal FA supplementation during pregnancy was significantly associated with ASD (P < .05), with an odds ratio (95% confidence interval of 3.69 (1.76, 7.76)). Also was associated with macrocephaly (P < .05), odds ratio (95% confidence interval) were 8.13 (1.63, 40.61) and 4.16 (1.18, 14.60), respectively. The incidence of abnormal HC was higher in the ASD group than that in the TD group. Maternal FA supplementation during pregnancy may be negatively associated with the occurrence of ASD and abnormal HC in the offspring. Further examination of the role of maternal health status in the etiology of ASD is recommended.

Effect of Anesthesia During Pregnancy, Delivery, and Childhood on Autism Spectrum Disorder: A Systematic Review and Meta-analysis

To investigate the association between exposure to anesthesia during three periods of pregnancy, delivery, and childhood and autism spectrum disorder (ASD). PubMed, Scopus, Web of Science, Embase, Google Scholar, PsycArticles, and PsycINFO were searched from the date of database inception to 1 December 2022. Studies reported the association between exposure to anesthesia during pregnancy, delivery, and childhood and ASD were included. Extracted variables included hazard ratio (HR), relative risk or odds ratio, standard error, and 95% confidence interval (CI). Effect estimates were pooled using random-effects meta-analysis. In total, 16 studies including 8,156,608 individuals were included in the meta-analysis. Labor epidural anesthesia during delivery was associated with ASD in the general population (adjusted HR = 1.16, 95% CI, 1.06-1.28) but not in the sibling population (adjusted HR = 1.06, 95% CI, 0.98-1.15). Other anesthesia during delivery was not associated with ASD (general population: adjusted HR = 1.08, 95% CI, 0.99-1.17; sibling population: adjusted HR = 1.20, 95% CI, 0.81-1.79). Three studies suggested that exposure to anesthesia during pregnancy was associated with ASD in offspring (adjusted HR = 2.15, 95% CI, 1.32-3.48). There was no significant association between exposure to general anesthesia during childhood and ASD (adjusted HR = 1.02, 95% CI, 0.60-1.72). This meta-analysis did not confirm the association between exposure to anesthesia during labour and ASD. Previous observational studies used the neurotoxicity of anesthesia to biologically explain significant associations, but in fact different controls for confounding factors led to differences in associations. The evidence for pregnancy and childhood was limited given the small number of studies in these periods.

Gene×environment interactions in autism spectrum disorders

There is credible evidence that environmental factors influence individual risk and/or severity of autism spectrum disorders (hereafter referred to as autism). While it is likely that environmental chemicals contribute to the etiology of autism via multiple mechanisms, identifying specific environmental factors that confer risk for autism and understanding how they contribute to the etiology of autism has been challenging, in part because the influence of environmental chemicals likely varies depending on the genetic substrate of the exposed individual. Current research efforts are focused on elucidating the mechanisms by which environmental chemicals interact with autism genetic susceptibilities to adversely impact neurodevelopment. The goal is to not only generate insights regarding the pathophysiology of autism, but also inform the development of screening platforms to identify specific environmental factors and gene×environment (G×E) interactions that modify autism risk. Data from such studies are needed to support development of intervention strategies for mitigating the burden of this neurodevelopmental condition on individuals, their families and society. In this review, we discuss environmental chemicals identified as putative autism risk factors and proposed mechanisms by which G×E interactions influence autism risk and/or severity using polychlorinated biphenyls (PCBs) as an example.