Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 3 complete abstracts (864 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
Wide continuum of associated cognitive and neurobehavioral disorders, including, but not limited to, three core-defining features: impairments in socialization, impairments in verbal and nonverbal communication, and restricted and repetitive patterns of behaviors. (from dsm-v)
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Autistic Spectrum Disorder; Autistic Spectrum Disorders; Disorder, Autistic Spectrum; Autism Spectrum Disorders.
Where it fits in the MeSH classification
- Broader topics
- Child Development Disorders, Pervasive
- Narrower topics
- Asperger Syndrome; Autistic Disorder
Related concepts
- Dsm-V
Research landscape
PubMed indexes 53,831 records tagged with the MeSH heading “Autism Spectrum Disorder” (counts retrieved 2026-10-31). 23,683 of them (44.0%) were published from 2020 onward, and the busiest period so far is 2020 onward with 23,683 records.
Reviews account for 8,097 records (15.0%) and meta-analyses for 1,047. Randomized controlled trials number 1,435 (2.7%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 4,543 |
| 2000-2009 | 7,617 |
| 2010-2019 | 17,988 |
| 2020 onward | 23,683 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 8,097 | 15.0% |
| Meta-analyses | 1,047 | 1.9% |
| Randomized controlled trials | 1,435 | 2.7% |
Method: PubMed query "Autism Spectrum Disorder"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in psychiatry and psychology
Research on mental health and behaviour relies on questionnaires, interviews and rating scales rather than physical measurements, so how a condition was defined and measured shapes every result. Many studies are observational or small, placebo responses can be large, and findings in one group or culture may not carry over to another. Nothing on this page is advice about diagnosis or treatment; anyone worried about their mental health should talk to a qualified clinician. Check how outcomes were measured, who took part and how long they were followed.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Prenatal Air Pollution Exposure and Autism Spectrum Disorder in the ECHO Consortium | 2026 | Research article Design not recorded in structured metadata | 3 | cc by PMID 42428257 · DOI · PMC13347653 |
| Developing a consensus research definition for profound autism using a modified Delphi method | 2026 | Research article Design not recorded in structured metadata | 2 | cc by PMID 42380932 · DOI · PMC13326320 |
| Functional Heterogeneity of the Autism Spectrum Disorder-Associated Gut Microbial Ecosystem Revealed by Fecal Lipopolysaccharides and Bacterial Proteomic Profiling | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42809586 · DOI · PMC13623111 |
Prenatal Air Pollution Exposure and Autism Spectrum Disorder in the ECHO Consortium [1]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundThe relationship between prenatal exposure to low-level air pollution and child autism spectrum disorder (ASD) is unclear.
- Closing excerpt
- DiscussionAssociations with ASD outcomes were present even at low levels of air pollutants.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (300 words)
BackgroundThe relationship between prenatal exposure to low-level air pollution and child autism spectrum disorder (ASD) is unclear.ObjectiveTo examine associations of prenatal air pollution exposure with autism.MethodsWe analyzed data from 8,035 mother-child pairs from 44 United States cohorts in the Environmental influences on Child Health Outcomes (ECHO) Cohort. Fine particulate matter (PM2.5), nitrogen dioxide (NO2), and 8-h-max ozone (O3) levels were estimated at residential addresses during pregnancy. Parents rated children's autism-related traits using the Social Responsiveness Scale (SRS) (mean age 9.4 years, SD = 3.6) and reported physician-diagnosed ASD. We examined associations of the three air pollutants with SRS scores (10th, 50th, and 90th quantiles) using quantile regression and with ASD diagnosis using logistic regression. Models were run within census divisions, and coefficients were pooled in a meta-analysis.ResultsAverage (SD) pregnancy exposures were 9.3 μg/m3 (2.7) for PM2.5, 21.8 ppb (8.8) for NO2, and 40.3 ppb (5.5) for O3, with variations across census divisions. The median SRS T-score was 46 (IQR = 41 to 52), and 444 children (5.5%) had an ASD diagnosis. Higher PM2.5 was associated with higher SRS scores at the 10th quantile (β = 0.74, 95% CI: 0.09, 1.40) but not at the median or highest quantile. The association between PM2.5 and ASD diagnosis was highly heterogeneous, with associations present in the South Central, Mountain, and Pacific census divisions. Heterogeneity was also high in the association between NO2 and SRS at the median and only in the mid-Atlantic, West North Central, and South Atlantic census divisions. Higher O3 was associated with higher SRS scores at the median (β per IQR increment = 0.83, 95% CI: 0.05, 1.61) and highest quantile (β = 2.19, 95% CI: 0.06, 4.32) in the meta-analysis. Higher O3 also was associated with ASD.DiscussionAssociations with ASD outcomes were present even at low levels of air pollutants.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42428257 · DOI · PMC13347653
Developing a consensus research definition for profound autism using a modified Delphi method [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundThe diagnostic term, autism spectrum disorder, encompasses the full range of impairments associated with the autism spectrum, a significant change from earlier DSM definitions that identified various subtypes of autism.
- Closing excerpt
- Adoption of this definition could improve comparability across research studies, enhance the impact and generalizability of results, and better target interventions and supports for this high-needs group.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (381 words)
BackgroundThe diagnostic term, autism spectrum disorder, encompasses the full range of impairments associated with the autism spectrum, a significant change from earlier DSM definitions that identified various subtypes of autism. However, the majority of autism-related research and cultural representations in recent years has focused on autistic individuals with strong language and cognitive abilities. In 2021, the administrative term Profound Autism (PA) was proposed by a Lancet Commission to draw attention to autistic people whose impairments require lifelong, round-the-clock care. The initial definition of PA included a minimum age and requiring 24/7 access to an adult to ensure safety, and suggested considering IQ, and verbal ability when defining this group. However, researchers have subsequently utilized widely varying criteria in studies of this group, producing results that are difficult to compare and limit the potential for the identification of this group to advance knowledge about their strengths and needs.MethodsTo address the need for studies that use comparable samples and increase clarity in communication and interpretation of results, we carried out a systematic, multi-stage Delphi consensus study with over 70 participants who identified as researchers, caregivers, autistic individuals, and clinicians, to measure consensus on components of a research definition of PA. A series of questions was developed for the primary domains of interest.ResultsAfter two rounds of review and voting, 76% of the respondents agreed on a research definition of PA of: adaptive functioning well below age level, requiring adult supervision to ensure physical and mental health, safety and well-being, being at least 8 years old, diagnosed with ASD, and having severely impaired cognitive abilities (reflected by IQ score below 50) and/or not verbally communicating other than single words or fixed phrases used predominantly to have their basic needs met.LimitationsVariations in access to measurement tools, as well as access to services across the world, limit the utility of this definition outside research practices, and a response rate of 58% yielded a final round sample size of 78 that may underrepresent portions of the stakeholder community and was overwhelmingly composed of respondents from the United States.ConclusionsBased on these findings, a new working research definition of profound autism is proposed. Adoption of this definition could improve comparability across research studies, enhance the impact and generalizability of results, and better target interventions and supports for this high-needs group.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42380932 · DOI · PMC13326320
Functional Heterogeneity of the Autism Spectrum Disorder-Associated Gut Microbial Ecosystem Revealed by Fecal Lipopolysaccharides and Bacterial Proteomic Profiling [3]
Abstract reading summary — source excerpts
- Opening excerpt
- The etiology of pediatric autism spectrum disorder (ASD) has been increasingly linked to alterations in the gut-brain axis, highlighting the intricate bidirectional communication between gut microbiota and central nervous system.
- Closing excerpt
- These findings suggest that gut microbiota in ASD children are associated with a functionally heterogeneous microbial ecosystem characterized by altered immunostimulatory molecular outputs despite the absence of massive taxonomic shifts, with potential relevance for neuroimmune dysregulation.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (183 words)
The etiology of pediatric autism spectrum disorder (ASD) has been increasingly linked to alterations in the gut-brain axis, highlighting the intricate bidirectional communication between gut microbiota and central nervous system. The molecular mechanisms of this communication are poorly understood. Here we investigated whether ASD-associated gut microbiota could exhibit altered inflammatory molecular outputs by integrating chemistry-driven profiling of fecal lipopolysaccharides (LPS), functional bacterial proteomics, and neuroimmune cellular assays. Structural analyses revealed that LPS from non-autistic healthy donors (NASD) displayed highly conserved carbohydrate and lipid A signatures dominated by hypo-acylated mono-phosphorylated species typically associated with immunomodulatory Bacteroides-derived LPS. In contrast, LPS from ASD children exhibited increased structural heterogeneity. These molecular alterations were functionally reflected in human HMC3 microglial cells, where ASD-derived fecal LPS induced stronger IL-6 and IL-8 release compared with NASD-derived LPS, indicating enhanced neuroinflammatory potential. Functional proteomic profiling disclosed broadly comparable microbial compositions but marked metabolic divergence. These findings suggest that gut microbiota in ASD children are associated with a functionally heterogeneous microbial ecosystem characterized by altered immunostimulatory molecular outputs despite the absence of massive taxonomic shifts, with potential relevance for neuroimmune dysregulation.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42809586 · DOI · PMC13623111
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Age at onset of mental disorders worldwide: large-scale meta-analysis of 192 epidemiological studies [4]
- Research article Rare coding variation provides insight into the genetic architecture and phenotypic context of autism [5]
- Research article The global prevalence of autism spectrum disorder: a comprehensive systematic review and meta-analysis [6]
- Research article The Effects of Exercise Interventions on Executive Functions in Children and Adolescents with Autism Spectrum Disorder: A Systematic Review and Meta-analysis [7]
- Research article Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis [8]
- Research article Mortality in Persons With Autism Spectrum Disorder or Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-analysis [9]
Full-text reviews on EvidenceLib
Open-access review articles about this topic, reproduced in full with authors, licence and references.
The association between maternal prenatal folic acid and multivitamin supplementation and autism spectrum disorders in offspring: An umbrella review
Biruk Beletew Abate, Biruk Shalmeno Tusa, Ashenafi Kibret Sendekie et al. · PLOS One 2025 · CC BY 4.0
Early non-social behavioural indicators of autism spectrum disorder (ASD) in siblings at elevated likelihood for ASD: a systematic review
Daniela Canu, Sara Van der Paelt, Ricardo Canal-Bedia et al. · European Child & Adolescent Psychiatry 2021 · CC BY 4.0
Migration or ethnic minority status and risk of autism spectrum disorders and intellectual disability: systematic review
Maki Morinaga, Dheeraj Rai, Anna-Clara Hollander et al. · The European Journal of Public Health 2021 · CC BY 4.0
Composition of Gut Microbiota in Children with Autism Spectrum Disorder: A Systematic Review and Meta-Analysis
Lucía Iglesias-Vázquez, Georgette Van Ginkel Riba, Victoria Arija et al. · Nutrients 2020 · CC BY 4.0
The Promising Role of Probiotics in Managing the Altered Gut in Autism Spectrum Disorders
Basma Abdellatif, Clare McVeigh, Ghizlane Bendriss et al. · International Journal of Molecular Sciences 2020 · CC BY 4.0
References
- Ghassabian A, Dickerson AS, Wang Y, Braun JM, Bennett DH, Croen LA, et al.. Prenatal Air Pollution Exposure and Autism Spectrum Disorder in the ECHO Consortium. . 2026. PMID 42428257 · DOI · PMC13347653
- Siegel M, Lord CL, Tager-Flusberg H, Ursitti J, Halladay A, Singer AT. Developing a consensus research definition for profound autism using a modified Delphi method. . 2026. PMID 42380932 · DOI · PMC13326320
- De Chiara S, Di Somma A, Mazziotti V, Coppola S, Oglio F, Tammaro L, et al.. Functional Heterogeneity of the Autism Spectrum Disorder-Associated Gut Microbial Ecosystem Revealed by Fecal Lipopolysaccharides and Bacterial Proteomic Profiling. . 2026. PMID 42809586 · DOI · PMC13623111
- Solmi M, Radua J, Olivola M, Croce E, Soardo L, Salazar de Pablo G, et al.. Age at onset of mental disorders worldwide: large-scale meta-analysis of 192 epidemiological studies. Mol Psychiatry. 2022. PMID 34079068 · DOI · PMC8960395
- Fu JM, Satterstrom FK, Peng M, Brand H, Collins RL, Dong S, et al.. Rare coding variation provides insight into the genetic architecture and phenotypic context of autism. Nat Genet. 2022. PMID 35982160 · DOI · PMC9653013
- Salari N, Rasoulpoor S, Rasoulpoor S, Shohaimi S, Jafarpour S, Abdoli N, et al.. The global prevalence of autism spectrum disorder: a comprehensive systematic review and meta-analysis. Ital J Pediatr. 2022. PMID 35804408 · DOI · PMC9270782
- Liang X, Li R, Wong SHS, Sum RKW, Wang P, Yang B, et al.. The Effects of Exercise Interventions on Executive Functions in Children and Adolescents with Autism Spectrum Disorder: A Systematic Review and Meta-analysis. Sports Med. 2022. PMID 34468951 · DOI
- Kallitsounaki A, Williams DM. Autism Spectrum Disorder and Gender Dysphoria/Incongruence. A systematic Literature Review and Meta-Analysis. J Autism Dev Disord. 2023. PMID 35596023 · DOI · PMC10313553
- Catalá-López F, Hutton B, Page MJ, Driver JA, Ridao M, Alonso-Arroyo A, et al.. Mortality in Persons With Autism Spectrum Disorder or Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-analysis. JAMA Pediatr. 2022. PMID 35157020 · DOI · PMC8845021
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.