The maternal immune activation hypothesis has gained attention over the past 2 decades as a potential contributor to the etiology of autism. This hypothesis posits that maternal conditions associated with inflammation during pregnancy may increase the risk of autism in offspring. Autism is highly heritable, and causal environmental contributors to autism largely remain elusive. We review studies on maternal conditions during pregnancy, all associated with some degree of systemic inflammation, namely maternal infections, autoimmunity, and high body mass index. We also review studies of inflammatory markers in biological samples collected from mothers during pregnancy or from neonates and their relationship with autism assessed in children later in life. Recent reports indicate familial clustering of autism, autoimmunity, and infections, as well as genetic correlations between autism and aspects of immune function. Given this literature, there is an apparent risk of confounding of the reported associations between inflammatory exposures and autism by familial genetic factors in both clinical and epidemiological cohort studies. We highlight recent studies that have attempted to address potential confounding to assess evidence of causal effects of inflammation during early life in autism.

Congenital cytomegalovirus (cCMV) is the leading cause of neurodevelopmental and hearing impairment resulting from in utero infection, affecting over a million infants globally each year. Early antiviral treatment can limit sequelae; however, most newborns are diagnosed late-or not at all-due to the lack of universal screening. Ensuring the availability of appropriate screening tools is critical to facilitate accurate and timely cCMV diagnosis.

A high-sensitivity, high-throughput commercial CMV PCR kit targeting the RRP30 control gene and a conserved region of CMV DNA was provided by Revvity and tested in three population groups: (1) leftover dried blood spot (DBS) samples from the UK newborn screening programme, (2) DBS samples from children with CMV viraemia unrelated to cCMV, and (3) DBS and dried saliva samples from infants with and without cCMV.

Of 3,345 anonymised newborn DBS samples analysed, CMV was detected in 22 cases (0.66%), with a mean cycle threshold value of 36.70 (range 31.87-41.68). Assay development demonstrated a sensitivity of 2.04 CMV IU per reaction. This level of sensitivity was replicated using DBS samples prepared from infant/child blood samples with known levels of CMV, suggesting that the sensitivity reflects 2,000-3,000 CMV IU/mL blood.

We demonstrated high analytical sensitivity of the qPCR assay with an optimal extraction protocol, making it an effective strategy for cCMV screening using DBS samples. These data suggest a potential cCMV incidence rate of up to 0.66% in the United Kingdom, equivalent to 3,960 infants per year, 25% of whom may develop long-term sequelae, which could be improved through early diagnosis and treatment.

Elevated cytokine levels, including IL-6 and IL-1β, can contribute to persistent brain inflammation in children with autism and cytomegalovirus (CMV) infection, exacerbating autism-related behaviours and symptoms. This study evaluates the impact of CMV-induced cytokine increases on the eating behaviours and sensory profiles of children with autism.

A cross-sectional design was employed, involving children aged two to five years (CMV-reactive IgG), with ASD (n= 98) and TD (n = 96). Serological tests using ELISA were conducted to measure IgG CMV, IL-6, and IL-1β biomarkers. Eating behaviours were evaluated using the BAMBI (Brief Autism Mealtime Behaviour Inventory), and sensory profiles were assessed using the SSP (Short Sensory Profile). Statistical analyses were performed using Spearman's rank and chi-square tests.

The results show that autism significantly affects children's eating behaviours and sensory profiles (p < 0.001), with notable differences found between the groups. Correlation analysis revealed a significant association between IgG CMV and IL-6 (p = 0.026) and IL-1β (p = 0.014) in the ASD group. Additionally, eating behaviours (food refusal and limited variety) in ASD correlated with IL-6 and IL-1β. Sensory characteristics, such as tactile sensitivity, were found to correlate with IL-6 (p = 0.027) and IL-1β (p = 0.002) in the ASD group.

These findings suggest that CMV-infected children with autism are at increased risk of IL-6 and IL-1β dysregulation, contributing to sensory processing issues and eating behaviours. Further research is needed to enhance CMV testing protocols and better understand the virus's role in the development of sensory and behavioural issues in children with autism.

The potential roles of viral infections in neurodevelopmental disorders (NDDs) have been suggested based on previous studies. Given the high prevalence of human herpesviruses (HHVs), the associations between HHVs infection and the risk of NDDs warrant explored.

Our study employs a two-sample Mendelian randomization (MR) analysis and systematic review with meta-analysis to investigate whether genetically predicted HHVs infection are linked to three main childhood NDDs-autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and Tourette syndrome (TS). We utilized genetic variants associated with HHV infections in genome-wide association study (GWAS) summary datasets of European populations to establish instrumental variables and statistics for three NDDs obtained from Psychiatric Genomics Consortium. MR analysis was performed using inverse-variance weighted, MR Egger, weighted median, simple median, weighted mode, and MR-PRESSO. In addition, publications associating HHVs infection with three NDDs were systematically searched using PubMed, Web of Science, and three Chinese databases for meta-analyses.

The MR results found no evidence to support a link between genetically predicted HHVs infection and the risk of NDDs based on existing datasets. Twenty-seven observational studies on children with HHVs infection and NDDs were considered eligible. Meta-analysis showed that cytomegalovirus and HHV-6 infection were related with ASD, while Epstein-Barr virus and cytomegalovirus infection were associated with TD in Chinese population.

These results contribute to a comprehensive understanding of the possibilities underlying HHV infections in affecting childhood NDDs. Further research is necessary to include larger and more robust statistics of HHV infections and NDDs.

This systematic review was registered at PROSPERO as CRD42024554169. Retrospectively registered 26 July 2024.

To examine the association between congenital cytomegalovirus (cCMV) and autism spectrum disorder (ASD) administrative diagnoses in US children.

Cohort study using 2014 to 2020 Medicaid claims data. We used diagnosis codes to identify cCMV (exposure), ASD (outcome), and covariates among children enrolled from birth through ≥4 to <7 years. Covariates include central nervous system (CNS) anomaly or injury diagnosis codes, including brain anomaly, microcephaly within 45 days of birth, cerebral palsy, epilepsy, or chorioretinitis. We used Cox proportional hazards regression models to estimate hazard ratios and 95% confidence intervals, overall and stratified by sex, birth weight and gestational age outcome (low birth weight or preterm birth), and presence of CNS anomaly or injury.

Among 2 989 659 children, we identified 1044 (3.5 per 10 000) children with cCMV and 74 872 (25.0 per 1000) children with ASD. Of those with cCMV, 49% also had CNS anomaly or injury diagnosis codes. Children with cCMV were more likely to have ASD diagnoses (hazard ratio: 2.5; 95% confidence interval: 2.0-3.2, adjusting for birth year, sex, and region). This association differed by sex and absence of CNS anomaly or injury but not birth outcome.

Children with (versus without) cCMV diagnoses in Medicaid claims data, most of whom likely had symptomatic cCMV, were more likely to have ASD diagnoses. Future research investigating ASD risk among cohorts identified through universal cCMV screening may help elucidate these observed associations.

Cytomegalovirus (CMV) belongs to the Herpesviridae family and is also known as human herpesvirus type 5. It is a common virus that usually doesn't cause any symptoms in healthy individuals. However, once infected, the virus remains in the host's body for life and can reactivate when the host's immune system weakens. This virus has been linked to several neurological disorders, including Alzheimer's disease, Parkinson's disease, Autism spectrum disorder, Huntington's disease (HD), ataxia, Bell's palsy (BP), and brain tumours, which can cause a wide range of symptoms and challenges for those affected. CMV may influence inflammation, contribute to brain tissue damage, and elevate the risk of moderate-to-severe dementia. Multiple studies suggest a potential association between CMV and ataxia in various conditions, including Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, acute cerebellitis, etc. On the other hand, the evidence regarding CMV involvement in BP is conflicting, and also early indications of a link between CMV and HD were challenged by subsequent research disproving CMV's presence. This systematic review aims to comprehensively investigate any link between the pathogenesis of CMV and its potential role in neurological disorders and follows the preferred reporting items for systematic review and meta-analysis checklist. Despite significant research into the potential links between CMV infection and various neurological disorders, the direct cause-effect relationship is not fully understood and several gaps in knowledge persist. Therefore, continued research is necessary to gain a better understanding of the role of CMV in neurological disorders and potential treatment avenues.

Autism spectrum disorder (ASD) is a group of heterogeneous, multi-factorial, neurodevelopmental disorders resulting from genetic and environmental factors interplay. Infection is a significant trigger of autism, especially during the critical developmental period. There is a strong interplay between the viral infection as a trigger and a result of ASD. We aim to highlight the mutual relationship between autism and viruses. We performed a thorough literature review and included 158 research in this review. Most of the literature agreed on the possible effects of the viral infection during the critical period of development on the risk of developing autism, especially for specific viral infections such as Rubella, Cytomegalovirus, Herpes Simplex virus, Varicella Zoster Virus, Influenza virus, Zika virus, and severe acute respiratory syndrome coronavirus 2. Viral infection directly infects the brain, triggers immune activation, induces epigenetic changes, and raises the risks of having a child with autism. At the same time, there is some evidence of increased risk of infection, including viral infections in children with autism, due to lots of factors. There is an increased risk of developing autism with a specific viral infection during the early developmental period and an increased risk of viral infections in children with autism. In addition, children with autism are at increased risk of infection, including viruses. Every effort should be made to prevent maternal and early-life infections and reduce the risk of autism. Immune modulation of children with autism should be considered to reduce the risk of infection.

Autism is a neurodevelopmental disorder with a significantly increased incidence rate across the world over the past few years. Toxoplasmosis and cytomegalovirus (CMV) infection are globally prevalent and have been associated with diverse neurological and psychiatric disorders. A few studies have demonstrated the role of toxoplasmosis and CMV as potential etiological factors for autism. Accordingly, this study was performed to estimate the relationship between toxoplasmosis and CMV infection in children with autism as well as to assess their impact on the Childhood Autism Rating Scale (CARS) score. A total of 45 autistic children (6 girls, 39 boys) and 45 (21 girls, 24 boys) healthy control children were enrolled in our study. Their blood samples were collected and tested for the presence of Toxoplasma and CMV (IgG and IgM) antibodies and DNA by ELISA and real-time PCR (RT-PCR), respectively. Toxoplasmosis was detected in 11 (24.4%) autistic children through the ELISA [10 (22.2%) IgG + /IgM - and 1 (2.2%) IgG + /IgM +]; however, RT-PCR assay recorded only 1 positive case (2.2%), while it was detected in 10 (22.2%) control children through ELISA [9 (20%) IgG + /IgM - and 1 (2.2%) IgG + /IgM +] and 1 (2.2%) by RT-PCR. On the other hand, CMV infection was detected in all autistic children with 44 (97.8%) testing positive by ELISA [24 (53.3%) IgG + /IgM - , 18 (40%) IgG + /IgM + and 2 (4.4%) IgG - /IgM +] and 25 (55.6%) testing positive by RT-PCR assay. In addition, ELISA assay recorded 43 (95.6%) [19 (42.2%) IgG + /IgM + and 22 (48.9%) IgG + /IgM - and 2 (4.4%) IgG-/IgM +] and RT-PCR recorded 21 (46.7%) positive samples in control children with CMV. No significant difference was noted between autistic and control children for the overall prevalence of Toxoplasma or/and CMV infection. Similarly, the CARS score indicated a non-significant difference with Toxoplasma or/and CMV infection. Our data does not show an association between autism and toxoplasmosis or/and CMV infection. Nevertheless, considering that autistic children are at a high risk of contracting these infections, further studies with a larger sample size are recommended.

This brief article gives a short overview of "comorbidity" in autism. The most common co-occurring disorders will be presented and discussed within the context of ESSENCE (Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations), a concept that provides a holistic perspective for neurodevelopmental disorders. The ESSENCE concept also considers the heterogeneous and changing clinical panorama of developmental disorders over time, and also the multifactorial etiologies, including so called behavioral phenotype syndromes. Aspects on behavioral interventions in autism are presented-interventions that need to be adapted and take into account all non-autism associated ESSENCE, including intellectual disability and Attention-Deficit/Hyperactivity Disorder (ADHD). The article also focuses on current research on pharmacological intervention based on the hypothesis of imbalance in excitatory/inhibitory transmitter systems in autism and some other ESSENCE.

Recent years have seen an impressive amount of research devoted to understanding the etiopathology of Autism Spectrum Disorder (ASD) and developing therapies for this syndrome. Because of the lack of biomarkers of ASD, this work has been largely based on the behavioral characterization of rodent models, based on a multitude of genetic and environmental manipulations. Here we highlight how the endocannabinoid system (ECS) has recently emerged within this context of mouse behavioral studies as an etiopathological factor in ASD and a valid potential therapeutic target. We summarize the most recent results showing alterations of the ECS in rodent models of ASD, and demonstrating ASD-like behaviors in mice with altered ECS, induced either by genetic or pharmacological manipulations. We also give a critical overview of the most relevant advances in designing treatments and novel mouse models for ASD targeting the ECS, highlighting the relevance of thorough and innovative behavioral approaches to investigate the mechanisms acting underneath the complex features of ASD.

Autism spectrum disorder (ASD) is a neurodevelopmental condition of the central nervous system (CNS) that presents with severe communication problems, impairment of social interactions, and stereotypic behaviours. Emerging studies indicate possible associations between viral infections and neurodegenerative and neurobehavioural conditions including autism. Viral infection during critical periods of early in utero neurodevelopment may lead to increased risk of autism in the offspring. This review is aimed at highlighting the association between viral infections, including viruses similar to COVID-19, and the aetiology of autism. A literature search was conducted using Pubmed, Ovid/Medline, and Google Scholar database. Relevant search terms included "rubella and autism", "cytomegalovirus and autism", "influenza virus and autism", "Zika virus and autism", "COVID-19 and autism". Based on the search terms, a total of 141 articles were obtained and studies on infants or children with congenital or perinatal viral infection and autistic behaviour were evaluated. The possible mechanisms by which viral infections could lead to autism include direct teratogenic effects and indirect effects of inflammation or maternal immune activation on the developing brain. Brain imaging studies have shown that the ensuing immune response from these viral infections could lead to disruption of the development of brain regions and structures. Hence, long-term follow up is necessary for infants whose mothers report an inflammatory event due to viral infection at any time during pregnancy to monitor for signs of autism. Research into the role of viral infection in the development of ASD may be one avenue of improving ASD outcomes in the future. Early screening and diagnosis to detect, and maybe even prevent ASD are essential to reduce the burden of this condition.

Cytomegalovirus is the most common congenital infection, affecting 0.5-2% of all live births and the main nongenetic cause of congenital sensorineural hearing loss and neurological damage. Congenital cytomegalovirus can follow maternal primary infection or nonprimary infection. Sensorineurological morbidity is confined to the first trimester with up to 40-50% of infected neonates developing sequelae after first-trimester primary infection. Serological testing before 14 weeks is critical to identify primary infection within 3 months around conception but is not informative in women already immune before pregnancy. In Europe and the United States, primary infection in the first trimester are mainly seen in young parous women with a previous child younger than 3 years. Congenital cytomegalovirus should be evoked on prenatal ultrasound when the fetus is small for gestation and shows echogenic bowel, effusions, or any cerebral anomaly. Although the sensitivity of routine ultrasound in predicting neonatal symptoms is around 25%, serial targeted ultrasound and magnetic resonance imaging of known infected fetuses show greater than 95% sensitivity for brain anomalies. Fetal diagnosis is done by amniocentesis from 17 weeks. Prevention consists of both parents avoiding contact with body fluids from infected individuals, especially toddlers, from before conception until 14 weeks. Candidate vaccines failed to provide more than 75% protection for >2 years in preventing cytomegalovirus infection. Medical therapies such as cytomegalovirus hyperimmune globulins aim to reduce the risk of vertical transmission but 2 randomized controlled trials have not found any benefit. Valaciclovir given from the diagnosis of primary infection up to amniocentesis decreased vertical transmission rates from 29.8% to 11.1% in the treatment group in a randomized controlled trial of 90 pregnant women. In a phase II open-label trial, oral valaciclovir (8 g/d) given to pregnant women with a mildly symptomatic fetus was associated with a higher chance of delivering an asymptomatic neonate (82%), compared with an untreated historical cohort (43%). Valganciclovir given to symptomatic neonates is likely to improve hearing and neurological symptoms, the extent of which and the duration of treatment are still debated. In conclusion, congenital cytomegalovirus infection is a public health challenge. In view of recent knowledge on diagnosis and pre- and postnatal management, health care providers should reevaluate screening programs in early pregnancy and at birth.

Association of congenital cytomegalovirus (CMV) infection with autism spectral disorder (ASD) has been suggested since 1980s. Despite the observed association, its role as a risk factor for ASD remains to be defined. In the present review, we systematically evaluated the available evidence associating congenital CMV infection with ASD using PubMed, Web of Science, Cochrane Library, and Embase databases. Any studies on children with CMV infection and ASD were evaluated for eligibility and three observational studies were included in meta-analysis. Although a high prevalence of congenital CMV infection in ASD cases (OR 11.31, 95% CI 3.07-41.66) was indicated, too few events (0-2 events) in all included studies imposed serious limitations. There is urgent need for further studies to clarify this issue.

Congenital cytomegalovirus infection (cCMV) can cause symptoms at birth as well as long-term impairment. This study estimates cCMV-related healthcare costs in the Netherlands in early childhood.

In a nationwide retrospective cohort study, 156 children with cCMV were identified by testing 31 484 neonatal dried blood spots for cCMV. Use of healthcare resources in the first 6 years of life by children with cCMV and a matched cCMV-negative control group were analysed. Mean costs per child were calculated by multiplying healthcare resource use by its reference prices.

Children with cCMV were compared with cCMV-negative children.

The average total healthcare costs per child were based on the average costs for hospital admissions and consultations by healthcare providers.

Mean healthcare costs of children with cCMV (€6113, n=133) were higher than children without cCMV (€3570, n=274), although statistically not significant, with a mean difference of €2544 (95% CI €-451 to €5538). The costs of children with long-term impairment were two times higher in children with cCMV (€17 205) compared with children without cCMV (€8332).

Children with cCMV, especially those with long-term impairment and those symptomatic at birth, accrue higher healthcare costs than cCMV-negative children in the first 6 years of life, although this is not statistically significant. This economic impact is of importance in the evaluation of preventive measures against cCMV.

NTR3582.

Autism spectrum disorders (ASD) are neurodevelopmental disorders without a definitive etiology in most cases. Environmental factors, such as viral infections, have been linked with anomalies in brain growth, neuronal development, and functional connectivity. Congenital cytomegalovirus (CMV) infection has been associated with the onset of ASD in several case reports. The aim of this study was to evaluate the prevalence of congenital CMV infection in children with ASD and in healthy controls.

The CMV genome was tested by polymerase chain reaction (PCR) on dried blood spots collected at birth from 82 children (38 with ASD and 44 controls).

The prevalence of congenital CMV infection was 5.3% (2/38) in cases and 0% (0/44) in controls (p=0.212).

The infection rate was about 10-fold higher in patients with ASD than in the general Italian population at birth. For this reason, detection of CMV-DNA on dried blood spots could be considered in the work-up that is usually performed at ASD diagnosis to rule-out a secondary form. Given the potential prevention and treatment of CMV infection, this study could have intriguing consequences, at least for a group of patients with ASD.

This study aimed to estimate long-term impairment attributable to congenital cytomegalovirus infection (cCMV).

This nationwide cohort study retrospectively assessed cCMV in children born in 2008 in the Netherlands, testing 31 484 stored neonatal dried blood spots. Extensive medical data of cCMV-positive children (n=133) and matched cCMV-negative comparison children (n=274) up to 6 years of age were analysed.

Moderate to severe long-term impairment was diagnosed in 24.8% (33 out of 133) of all cCMV-positive children (53.8% in symptomatic, 17.8% in asymptomatic), compared with 12.0% (33 out of 274) of cCMV-negative children. Sensorineural hearing loss was seen only in five cCMV-positive children (3.8%). Developmental delays were diagnosed more often in cCMV-positive children than cCMV-negative children: motor (12.0% vs 1.5%), cognitive (6.0% vs 1.1%), and speech-language (16.5% vs 7.3%). Long-term impairment in multiple domains was more frequent in symptomatic (19.2%) and asymptomatic (8.4%) cCMV-positive children than cCMV-negative children (1.8%).

Children with cCMV were twice as likely to have long-term impairment up to the age of 6 years, especially developmental delays and sensorineural hearing loss, than cCMV-negative comparison children, with a risk difference of 12.8%. These insights into the risk of cCMV-associated impairment can help optimize care and stimulate preventive measures.

Congenital cytomegalovirus infection (cCMV) leads to impairment in 25% of cases. Fifty per cent of children with cCMV symptoms at birth have long-term impairment. The risk difference of moderate to severe long-term impairment between children with and without cCMV is 13%, attributable to cCMV. cCMV leads to motor, cognitive, and speech-language developmental delay in children.

The aim of this retrospective study, with prospective data collection, was to correlate congenital cytomegalovirus (CMV) infection with autism spectrum disorder (ASD) and to define its prevalence. Seventy proven congenitally-infected infants, born between 2007 and 2012, were referred to our centre for CMV diagnosis and follow-up, which consisted of a consolidated protocol allowing an early evaluation of autism. We considered four children 2-year old, two of whom, at the age of 3, were diagnosed with ASD demonstrating a 2-3 fold higher prevalence (2.86%), than that in general Italian population (0.66-1.36%).Our protocol enabled us to make the earliest diagnosis and highlight the role of the virus among other causes of autism, which may be a long term sequela of congenital CMV.

Human cytomegalovirus (HCMV) dormant infection can alter the expression of the hosts' microRNAs (miRNAs) and impact on the regulation of target genes. To investigate the differentially expressed miRNAs induced by HCMV in human glioma U251 cells, a comprehensive miRNA screen was performed. As a result, 19 up-regulated and 14 down-regulated miRNAs were determined. Of these, hsa-miR-27b (miR-27b) attracted our attention. MiR-27b levels in U251 cells increased 7.70-fold, 8.64-fold, and 4.78-fold, respectively, post 24 h, 48 h, and 72 h HCMV infection, compared to those in the mimic-infected cells, and this up-regulation was further confirmed by quantitative RT-PCR. The bioinformatic analyses show that miR-27b targets engrailed-2 (EN2) gene; however, the effect of miR-27b on EN2 is rarely encountered. In this study, we initially conducted dual luciferase assay to validate the target function of miR-27b on EN2. The results manifested that EN2 is a novel target of miR-27b, which could directly target the 3' untranslated region (3'-UTR) of the gene. We further found that the miR-27b transfected glioma U251 cells exhibited longer cell bodies with more synapses and multiple-angle shapes; moreover, Western blot detection revealed that the EN2 protein levels in these cells were significantly low. In conclusion, our study originally reports the up-regulation of miR-27b in HCMV-infected glioma cells. Our study also provides the first experimental evidence that miR-27b could affect glioma cells' growth, target EN2 and inhibit its expression in glioma cells. Our data indicate that miR-27b may be related to the development of neurological disorders with HCMV infection. The newly identified miR-27b/EN2 signal pathway may provide new insights into the glioma pathogenesis and a novel target for glioma therapy. Impact statement Our study is the first to demonstrate that the HCMV infection could alter the expression of cellular microRNAs of the host glioma cells, which may develop an understanding of the pathogenesis of the HCMV infection in the microRNA level. Recently, HCMV infection and engrailed-2 have been reported to be related to the autism spectrum disorder (ASD). In this study, we confirmed that engrailed-2 is the target of hsa-miR-27b. As far as we know, our findings of the hsa-miR-27b up-regulation in the HCMV-infected glioma cells, targeting engrailed-2 and inhibiting its expression have never been reported or documented. Our data indicate that miR-27b may be related to the development of neurological disorders with the HCMV infection. The newly identified miR-27b/EN2 signal pathway may provide new insights into the glioma pathogenesis and a novel target for glioma therapy.