Association between peripheral blood levels of C-reactive protein and Autism Spectrum Disorder in children: A systematic review and meta-analysis

The efficacy and safety of MDMA-assisted psychotherapy for treatment of posttraumatic stress disorder: A systematic review and meta-analysis from randomized controlled trials

3,4-methylenedioxymethamphetamine (MDMA), commonly known as ecstasy, is one of the most widely used illicit substances worldwide. MDMA-assisted psychotherapy has become a novel treatment for posttraumatic stress disorder (PTSD), and many randomized controlled trials (RCTs) have been performed over the past decade. Therefore, this study aimed to systematically review and demonstrate the efficacy and safety of MDMA-assisted psychotherapy for the treatment of PTSD. We conducted a systematic search of PubMed, Embase, and Web of Science databases up to October 27, 2023, selected RCTs assessing the efficacy and safety of MDMA-assisted psychotherapy for the treatment of PTSD, and evaluated their quality using the Cochrane risk of bias tool. Seven RCTs were selected from the retrieved references. The results revealed that MDMA-assisted psychotherapy effectively reduced the change from baseline score in the Clinician-Administered PTSD Scale in patients with PTSD compared with either placebo or active controls. However, MDMA causes a series of adverse events, including muscle tightness, nausea, and decreased appetite. To a certain extent, MDMA-assisted psychotherapy may improve symptoms in patients with PTSD. However, side effects and abuse issues still seriously hinder clinical application of MDMA.

Mechanistic perspective on the actions of vitamin a in autism spectrum disorder etiology

Vitamin A (VA) has many functions in the body, some of which are key for the development and functioning of the nervous system, while some others might indirectly influence neural function. Both hypovitaminosis and hypervitaminosis A can lead to clinical manifestations of concern for individuals and for general global health. Scientific evidence on the link between VA and autism spectrum disorder (ASD) is growing, with some clinical studies and accumulating results obtained from basic research using cellular and animal models. Remarkably, it has been shown that VA deficiency can exacerbate autistic symptomatology. In turn, VA supplementation has been shown to be able to improve autistic symptomatology in selected groups of individuals with ASD. However, it is important to recognize that ASD is a highly heterogeneous condition. Therefore, it is important to clarify how and when VA supplementation can be of benefit for affected individuals. Here we delve into the relationship between VA and ASD, discussing clinical observations and mechanistic insights obtained from research on selected autistic syndromes and laboratory models to advance in defining how the VA signaling pathway can be exploited for treatment of ASD.

Association between urinary phthalates and phthalate metabolites and cancer risk: A systematic review and meta-analysis

Phthalates, widely utilized in industrial products, are classified as endocrine-disrupting chemicals (EDCs). Although certain phthalate and their metabolites have been implicated in cancer development, the reported findings have exhibited inconsistencies. Therefore, we conducted the comprehensive literature search to assess the association between phthalate and their metabolites and cancer risk by identifying original studies measuring phthalates or their metabolites and reporting their correlation with cancer until July 4, 2023. The Odds Ratios (ORs) and corresponding 95% confidence intervals (CIs) were extracted and analyzed to estimate the risk. Pooled data from eleven studies, including 3101 cancer patients and 6858 controls, were analyzed using a fixed- or random-effects model based on heterogeneity tests. When comparing extreme categories of different phthalates and their metabolites, we observed a significant association between urinary phthalates and phthalate metabolites (MEHHP, MECPP, DBP and MBzP) and cancer risk. The findings of our meta-analysis reinforce the existing evidence that urinary phthalates and phthalate metabolites is strongly associated with cancer development. Further investigations are warranted to elucidate the underlying mechanisms of this association. These results may offer novel insights into cancer development.

A leaky gut dysregulates gene networks in the brain associated with immune activation, oxidative stress, and myelination in a mouse model of colitis

The gut and brain are increasingly linked in human disease, with neuropsychiatric conditions classically attributed to the brain showing an involvement of the intestine and inflammatory bowel diseases (IBDs) displaying an ever-expanding list of neurological comorbidities. To identify molecular systems that underpin this gut-brain connection and thus discover therapeutic targets, experimental models of gut dysfunction must be evaluated for brain effects. In the present study, we examine disturbances along the gut-brain axis in a widely used murine model of colitis, the dextran sodium sulfate (DSS) model, using high-throughput transcriptomics and an unbiased network analysis strategy coupled with standard biochemical outcome measures to achieve a comprehensive approach to identify key disease processes in both colon and brain. We examine the reproducibility of colitis induction with this model and its resulting genetic programs during different phases of disease, finding that DSS-induced colitis is largely reproducible with a few site-specific molecular features. We focus on the circulating immune system as the intermediary between the gut and brain, which exhibits an activation of pro-inflammatory innate immunity during colitis. Our unbiased transcriptomics analysis provides supporting evidence for immune activation in the brain during colitis, suggests that myelination may be a process vulnerable to increased intestinal permeability, and identifies a possible role for oxidative stress and brain oxygenation. Overall, we provide a comprehensive evaluation of multiple systems in a prevalent experimental model of intestinal permeability, which will inform future studies using this model and others, assist in the identification of druggable targets in the gut-brain axis, and contribute to our understanding of the concomitance of intestinal and neuropsychiatric dysfunction.

Association between interpregnancy interval and risk of autism spectrum disorder: a systematic review and Bayesian network meta-analysis

Although the risk of autism spectrum disorder (ASD) has been reported to be associated with interpregnancy intervals (IPIs), their association remains debatable due to inconsistent findings in existing studies. Therefore, the present study aimed to explore their association. PubMed, Embase, Web of Science, and the Cochrane Library were systematically retrieved up to May 25, 2022. An updated search was performed on May 25, 2023, to encompass recent studies. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). Our primary outcome measures were expressed as adjusted odds ratios (ORs). Given various control measures for IPI and diverse IPI thresholds in the included studies, a Bayesian network meta-analysis was performed. Eight studies were included, involving 24,865 children with ASD and 2,890,289 children without ASD. Compared to an IPI of 24 to 35 months, various IPIs were significantly associated with a higher risk of ASD (IPIs < 6 months: OR = 1.63, 95% CI 1.53-1.74, n = 5; IPIs of 6-11 months: OR = 1.50, 95% CI 1.42-1.59, n = 4; IPIs of 12-23 months: OR = 1.19, 95% CI 1.12-1.23, n = 10; IPIs of 36-59 months: OR = 0.96, 95% CI 0.94-0.99, n = 2; IPIs of 60-119 months: OR = 1.15, 95% CI 1.10-1.20, n = 4; IPIs > 120 months: OR = 1.57, 95% CI 1.43-1.72, n = 4). After adjusting confounding variables, our analysis delineated a U-shaped restricted cubic spline curve, underscoring that both substantially short (< 24 months) and excessively long IPIs (> 72 months) are significantly correlated with an increased risk of ASD.  Conclusion: Our analysis indicates that both shorter and longer IPIs might predispose children to a higher risk of ASD. Optimal childbearing health and neurodevelopmental outcomes appear to be associated with a moderate IPI, specifically between 36 and 60 months. What is Known: • An association between autism spectrum disorder (ASD) and interpregnancy intervals (IPIs) has been speculated in some reports. • This association remains debatable due to inconsistent findings in available studies. What is New: • Our study delineated a U-shaped restricted cubic spline curve, suggesting that both shorter and longer IPIs predispose children to a higher risk of ASD. • Optimal childbearing health and neurodevelopmental outcomes appear to be associated with a moderate IPI, specifically between 36 and 60 months.

A comparison between children and adolescents with autism spectrum disorders and healthy controls in biomedical factors, trace elements, and microbiota biomarkers: a meta-analysis

Introduction

Autism spectrum disorder (ASD) is a multifaceted developmental condition that commonly appears during early childhood. The etiology of ASD remains multifactorial and not yet fully understood. The identification of biomarkers may provide insights into the underlying mechanisms and pathophysiology of the disorder. The present study aimed to explore the causes of ASD by investigating the key biomedical markers, trace elements, and microbiota factors between children with autism spectrum disorder (ASD) and control subjects.

Methods

Medline, PubMed, ProQuest, EMBASE, Cochrane Library, PsycINFO, Web of Science, and EMBSCO databases have been searched for publications from 2012 to 2023 with no language restrictions using the population, intervention, control, and outcome (PICO) approach. Keywords including "autism spectrum disorder," "oxytocin," "GABA," "Serotonin," "CRP," "IL-6," "Fe," "Zn," "Cu," and "gut microbiota" were used for the search. The Joanna Briggs Institute (JBI) critical appraisal checklist was used to assess the article quality, and a random model was used to assess the mean difference and standardized difference between ASD and the control group in all biomedical markers, trace elements, and microbiota factors.

Results

From 76,217 records, 43 studies met the inclusion and exclusion criteria and were included in this meta-analysis. The pooled analyses showed that children with ASD had significantly lower levels of oxytocin (mean differences, MD = -45.691, 95% confidence interval, CI: -61.667, -29.717), iron (MD = -3.203, 95% CI: -4.891, -1.514), and zinc (MD = -6.707, 95% CI: -12.691, -0.722), lower relative abundance of Bifidobacterium (MD = -1.321, 95% CI: -2.403, -0.238) and Parabacteroides (MD = -0.081, 95% CI: -0.148, -0.013), higher levels of c-reactive protein, CRP (MD = 0.401, 95% CI: 0.036, 0.772), and GABA (MD = 0.115, 95% CI: 0.045, 0.186), and higher relative abundance of Bacteroides (MD = 1.386, 95% CI: 0.717, 2.055) and Clostridium (MD = 0.281, 95% CI: 0.035, 0.526) when compared with controls. The results of the overall analyses were stable after performing the sensitivity analyses. Additionally, no substantial publication bias was observed among the studies.

Interpretation

Children with ASD have significantly higher levels of CRP and GABA, lower levels of oxytocin, iron, and zinc, lower relative abundance of Bifidobacterium and Parabacteroides, and higher relative abundance of Faecalibacterium, Bacteroides, and Clostridium when compared with controls. These results suggest that these indicators may be a potential biomarker panel for the diagnosis or determining therapeutic targets of ASD. Furthermore, large, sample-based, and randomized controlled trials are needed to confirm these results.

The tryptophan catabolite or kynurenine pathway in autism spectrum disorder; a systematic review and meta-analysis

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social communication and interaction, as well as rigid and unchanging interests and behaviors. Several studies have reported that activated immune-inflammatory and nitro-oxidative pathways are accompanied by depletion of plasma tryptophan (TRP), increased competing amino acid (CAAs) levels, and activation of the TRP catabolite (TRYCAT) pathway. This study aims to systematically review and meta-analyze data on peripheral TRP, CAAs, TRYCAT pathway activity, and individual TRYCATs, including kynurenine (KYN) and kynurenic acid (KA) levels, in the blood and urine of ASD patients. After extensively searching PubMed, Google Scholar, and SciFinder, a total of 25 full-text papers were included in the analysis, with a total of 6653 participants (3557 people with ASD and 3096 healthy controls). Our results indicate that blood TRP and the TRP/CAAs ratio were not significantly different between ASD patients and controls (standardized mean difference, SMD = -0.227, 95% confidence interval, CI: -0.540; 0.085, and SMD = 0.158, 95% CI: -0.042; 0.359), respectively. The KYN/TRP ratio showed no significant difference between ASD and controls (SMD = 0.001, 95% CI: -0.169; 0.171). Blood KYN and KA levels were not significantly changed in ASD. Moreover, there were no significant differences in urine TRP, KYN, and KA levels between ASD and controls. We could not establish increases in neurotoxic TRYCATs in ASD. In conclusion, this study demonstrates no abnormalities in peripheral blood TRP metabolism, indoleamine 2,3-dioxygenase enzyme (IDO) activity, or TRYCAT production in ASD. Reduced TRP availability and elevated neurotoxic TRYCAT levels are not substantial contributors to ASD's pathophysiology.

The efficacy and safety of some new GABAkines for treatment of depression: A systematic review and meta-analysis from randomized controlled trials

Positive allosteric modulators of γ-aminobutyric acid-A (GABAA) receptors, or GABAkines, play important roles in the treatment of depression, epilepsy, insomnia, and other disorders. Recently, some new GABAkines (zuranolone and brexanolone) have been administrated to patients with major depressive disorder (MDD) or postpartum depression (PPD) in randomized controlled trials (RCTs). This study aims to systematically review and examine the efficacy and safety of zuranolone or brexanolone for treatment of depression. A systematic literature retrieval was conducted through August 20, 2023. RCTs evaluating the efficacy and safety of zuranolone or brexanolone for treatment of depression were included. Eight studies (nine reports) were identified in the study. The percentages of patients with PPD achieving Hamilton Depression Rating Scale (HAM-D) response and remission were significantly higher after brexanolone or zuranolone administration compared with placebo at different points. The percentages of patients with MDD achieving HAM-D response and remission were significantly increased during the zuranolone treatment period compared with placebo. In addition, zuranolone caused more adverse events in patients with MDD compared with placebo. Our findings support the effects of brexanolone on improving the core symptoms of depression in patients with PPD, and the potential of zuranolone in treating patients with MDD or PPD.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

The feasibility and efficiency for constructing arteriovenous fistula with <2 mm vein-a systematic review and meta-analysis

Background

Autogenous arteriovenous fistula (AVF) is an efficient hemodialysis access for patients with end-stage kidney disease (ESKD). The specific threshold of vein diameter still not reached a consensus.

Method

We conducted a comprehensive search in PubMed, Embase, and Web of Science databases for articles which comparing the treatment outcomes of AVF with 2 mm as vein diameter threshold. Fixed and random effect model were used for synthesis of results. Subgroup analysis was designed to assess the risk of bias.

Result

Eight high-quality articles were included finally. Among a total of 1,075 patients (675 males and 400 females), 227 and 809 patients possessed <2 mm and ≥2 mm vein respectively. Apart from gender and coronary artery disease (P < 0.05), there was no significant difference in age, diabetes, hypertension or radial artery between maturation and non-maturation groups. The functional maturation rate was lower in patients with <2 mm vein according to fixed effect model [OR = 0.19, 95% CI (0.12, 0.30), P < 0.01]. There was no significant difference in primary [OR = 0.63, 95% CI (0.12, 3.25), P = 0.58] or cumulative patency rates [OR = 0.40, 95% CI (0.13, 1.19), P = 0.10].

Conclusion

Vein diameter less than 2 mm has a negative impact on the functional maturation rate of AVF, while it does not affect the primary and cumulative patency rates (12 months).

A leaky gut dysregulates gene networks in the brain associated with immune activation, oxidative stress, and myelination in a mouse model of colitis

The gut and brain are increasingly linked in human disease, with neuropsychiatric conditions classically attributed to the brain showing an involvement of the intestine and inflammatory bowel diseases (IBDs) displaying an ever-expanding list of neurological comorbidities. To identify molecular systems that underpin this gut-brain connection and thus discover therapeutic targets, experimental models of gut dysfunction must be evaluated for brain effects. In the present study, we examine disturbances along the gut-brain axis in a widely used murine model of colitis, the dextran sodium sulfate (DSS) model, using high-throughput transcriptomics and an unbiased network analysis strategy coupled with standard biochemical outcome measures to achieve a comprehensive approach to identify key disease processes in both colon and brain. We examine the reproducibility of colitis induction with this model and its resulting genetic programs during different phases of disease, finding that DSS-induced colitis is largely reproducible with a few site-specific molecular features. We focus on the circulating immune system as the intermediary between the gut and brain, which exhibits an activation of pro-inflammatory innate immunity during colitis. Our unbiased transcriptomics analysis provides supporting evidence for immune activation in the brain during colitis, suggests that myelination may be a process vulnerable to increased intestinal permeability, and identifies a possible role for oxidative stress and brain oxygenation. Overall, we provide a comprehensive evaluation of multiple systems in a prevalent experimental model of intestinal permeability, which will inform future studies using this model and others, assist in the identification of druggable targets in the gut-brain axis, and contribute to our understanding of the concomitance of intestinal and neuropsychiatric dysfunction.

Effects of melatonin against acute kidney injury: A systematic review and meta-analysis

INTRODUCTION

Melatonin is a hormone synthesized by the pineal gland, and has antioxidative effects in reducing acute kidney injury (AKI). In the past three years, an increasing number of studies have evaluated whether melatonin has a protective effect on AKI. The study systematically reviewed and assessed the efficacy and safety of melatonin in preventing AKI.

MATERIAL AND METHODS

A systematic literature search was conducted in the PubMed, Embase, and Web of Science databases on February 15, 2023. Eligible records were screened according to the inclusion and exclusion criteria. The odds ratio and Hedges' gwith the corresponding 95% confidence intervals were selected to evaluate the effects of melatonin on AKI. We pooled extracted data using a fixed- or random-effects model based on a heterogeneity test.

RESULTS

There were five studies (one cohort study and four randomized controlled trials) included in the meta-analysis. Although the glomerular filtration rate (GFR) may be significantly improved by melatonin, the incidence of AKI was not significantly decreased in the melatonin group compared with the control group in randomized controlled trials (RCTs).

CONCLUSIONS

In our study, the present results do not support a direct effect of melatonin use on the reduction of AKI. More well-designed clinical studies with larger sample size are required in the future.

Evaluation of procalcitonin and C-reactive protein levels in children with autism spectrum disorder and attention deficit hyperactivity disorder

Inflammation is thought to play a role in the etiopathogenesis of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Procalcitonin (PCT) is an inflammatory biomarker released by thyroid parafollicular cells. CRP is systemic biomarker of inflammation. In this study, the hypothesis that PCT and C-reactive protein (CRP) might be indicators of increased inflammatory response was tested. For this purpose, PCT and CRP as well as other simple inflammatory markers were evaluated in children with ASD and ADHD. A total of 33 ASD, 36 ADHD, and 31 healthy controls were included in the study, who were similar in terms of gender and age. PCT, CRP, sedimentation and hemogram parameters (Neutrophil Lymphocyte Ratio) were measured in children aged 5-15 years. PCT and CRP values were found to be statistically significantly higher in ASD and ADHD children compared to healthy controls (p < 0.05). A positive correlation was found between PCT and CRP values (r: 0.358; p < 0.001). No significant correlations were found between disorder severity scale scores and PCT and CRP values (p > 0.05 for both). Accordingly, it is suggested that inflammation plays a role in the etiopathogenesis of these disorders. PCT and CRP may be used as inflammation markers.

Neuronal C-Reactive Protein/FcγRI Positive Feedback Proinflammatory Signaling Contributes to Nerve Injury Induced Neuropathic Pain

Neuropathic pain is difficult to treat in clinical practice, and the underlying mechanisms are insufficiently elucidated. Previous studies have demonstrated that the neuronal Fc-gamma-receptor type I (FcγRI) of the dorsal root ganglion (DRG) mediates antigen-specific pain. However, the mechanisms of neuronal FcγRI in neuropathic pain remain to be explored. Here, it is found that the activation of FcγRI-related signals in primary neurons induces neuropathic pain in a rat model. This work first reveals that sciatic nerve injury persistently activates neuronal FcγRI-related signaling in the DRG, and conditional knockout (CKO) of the FcγRI-encoding gene Fcgr1 in rat DRG neurons significantly alleviates neuropathic pain after nerve injury. C-reactive protein (CRP) is increased in the DRG after nerve injury, and CRP protein of the DRG evokes pain by activating neuronal FcγRI-related signals. Furthermore, microinjection of naive IgG into the DRG alleviates neuropathic pain by suppressing the activation of neuronal FcγRI. These results indicate that the activation of neuronal CRP/FcγRI-related signaling plays an important role in the development of neuropathic pain in chronic constriction injury (CCI) rats. The findings may provide novel insights into the neuroimmune responses after peripheral nerve injury and suggest potential therapeutic targets for neuropathic pain.

Deciduous tooth biomarkers reveal atypical fetal inflammatory regulation in autism spectrum disorder

Atypical regulation of inflammation has been proposed in the etiology of autism spectrum disorder (ASD); however, measuring the temporal profile of fetal inflammation associated with future ASD diagnosis has not been possible. Here, we present a method to generate approximately daily profiles of prenatal and early childhood inflammation as measured by developmentally archived C-reactive protein (CRP) in incremental layers of deciduous tooth dentin. In our discovery population, a group of Swedish twins, we found heightened inflammation in the third trimester in children with future ASD diagnosis relative to controls (n = 66; 14 ASD cases; critical window: -90 to -50 days before birth). In our replication study, in the US, we observed a similar increase in CRP in ASD cases during the third trimester (n = 47; 23 ASD cases; -128 to -21 days before birth). Our results indicate that the third trimester is a critical period of atypical fetal inflammatory regulation in ASD.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

Systemic inflammatory biomarkers in DSM-5 defined disorders and COVID-19: Evidence from published meta-analyses

On March 11, 2020, the World Health Organization declared the outbreak of the novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) as a global pandemic. At the center of SARS-CoV-2 is the activation of inflammatory markers; remarkably, interleukin 6 and C-reactive protein seem to be consistently elevated in patients with SARS-CoV-2. Here, we showed that increased systemic C-reactive protein and interleukin 6 are common biomarkers of both severe COVID-19 and DSM-5-defined disorders. However, it is not known whether patients with psychiatric disorders with preexisting increased interleukin 6 and C-reactive protein are more vulnerable to severe complications of COVID-19 because of the additive inflammatory processes.

Association Between Peripheral Blood Levels of Vitamin A and Autism Spectrum Disorder in Children: A Meta-Analysis

Vitamin A is an essential fat-soluble micronutrient that plays important roles in a surprisingly wide variety of biological processes from early growth and development to brain maintenance. Numerous clinical studies have been conducted to explore the relationship between peripheral vitamin A levels and autism spectrum disorder (ASD), but the results of these studies are controversial. Therefore, we assessed the association between peripheral vitamin A levels and ASD in the present meta-analysis. Relevant records were retrieved through the Embase, Web of Knowledge and PubMed databases up to 13 November 2020. Reference lists were also searched and analyzed. Hedges' g with its corresponding 95% confidence interval (CI) was used to assess the association between peripheral vitamin A levels and ASD. A fixed or random effects model was selected according to a heterogeneity test in overall and subgroup analyses. Five records (six studies) with 935 ASD children and 516 healthy children were included in the present study. Significantly decreased peripheral vitamin A concentrations were observed in ASD children compared with healthy children (Hedges' g = -0.600, 95% CI -1.153 to -0.048, P = 0.033). A similar result was also obtained after removing the studies identified by Galbraith plots. In addition, no obvious publication bias was found in the meta-analysis. The findings of our meta-analysis suggested decreased peripheral vitamin A levels in ASD children compared with healthy children. Further investigations into the effects of vitamin A on the development of ASD are warranted.