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Autism Spectrum Disorder (ASD) is a developmental disorder spectrum characterized by difficulties with social communication and interaction, and by restricted and/or repetitive behaviours, interests or activities. Although initial descriptions of autism emphasized a restricted profile of symptoms, current scientific research recognizes ASD as a spectrum encompassing individuals with a large variety of strengths, challenges and support needs. This article talks about the epidemiology of ASD, explores our current understanding of ASD’s etiology, describes diagnostic and intervention strategies, discusses continued challenges in research and care for individuals with ASD, and proposes next steps to improve the lives of people with ASD and their families.
ASD is formally defined in the DSM-5 as a single spectrum diagnosis that includes autism, Asperger’s syndrome, and pervasive developmental disorder–not otherwise specified (PDD-NOS). Core features include:
• Persistent deficits in social-emotional reciprocity (e.g., abnormal social approach or failure to start and carry on normal conversations)
• Lack of nonverbal communicative behavior (e.g., eye contact, gestures) to regulate interaction.
• Problems related to establishing, maintaining, and comprehending relationships
• Repetitive and restricted patterns of behavior, interests, or activities (e.g., stereotyped movements, routine, ritualistic behavior)
Severity is given on two scales-(1) social communication, and (2) restricted and repetitive behaviors-based on the level of support needed. Presentation varies widely, some people are nonverbal and require help with almost everything, while others have average language and intellectual abilities but struggle with subtle social cues.
Leo Kanner’s 1943 seminal account of “early infantile autism” and Hans Asperger’s concurrent work in Vienna consolidated autism as a separate diagnosis. For many years, ASD was conceptualized with narrow behavior-based criteria for diagnosis, and was frequently mistaken or ignored in persons without cognitive impairment. The introduction of the concept of the autism spectrum in the DSM-5 (2013) represented a dimensional approach that highlighted similar underlying constructs across traditional subtypes and streamlined the diagnostic process.
The estimated occurrence of ASD has increased progressively in the past few decades. In the US, prevalence was around 1.1% of children in 2008, and by 2018 had risen to 2.3% [^1]. The increase is probably related to expanded diagnostic criteria, improved screening tools, increased public and professional awareness and increased availability of services, among other things. How common ASD is varies worldwide, from around 0.4% in a few low-income regions to more than 3% in high-income countries, indicating disparities in recognition and distribution of resources.
Genetic Factors
Twin and family studies reveal the heritability of ASD ranges from 50% to 90%. Hundreds of these risk genes have been implicated, each with small effects. Rare, de novo mutations (e.g., CHD8, SHANK3) may be associated with significant risk; copy-number variants also play a role. Polygenic risk scores are being used more and more often to predict the likelihood of ASD, though their clinical utility is still experimental.
Environmental Influences
No single environmental factor causes ASD; though prenatal exposure to certain medications (eg, valproate) and advanced parental age, low birth weight, and preterm delivery have modest associations. Research into maternal metabolic conditions such as diabetes and obesity have proposed that inflammatory pathways might interact with gene susceptibility.
Neuroimaging studies have show atypical brain connectivity patterns (hypo- as well as hyperconnectivity) across distributed neural networks. Altered synaptic pruning, excitation and inhibition imbalance, and differences in minicolumn architecture could underlie core features. The diversity in results highlights the heterogeneity of ASD and suggests that several neurodevelopmental pathways may lead to common behavioural manifestations.
Early identification is important; reliable screening is possible at 18–24 months. Universal screening at 18 and 24 months is recommended during. pediatric visits; positive screens prompt a comprehensive evaluation.
The diagnostic evaluations are performed by a multidisciplinary team that often includes developmental pediatricians, psychologists, speech/language pathologists, and occupational therapists. The gold standards still are the Autism Diagnostic Observation Schedule (ADOS) and Autism Diagnostic Interview–Revised (ADI-R). It also includes cognitive testing, assessment of adaptive functioning, and screening for co-occurring conditions (e.g., ADHD, epilepsy).
Early, intensive interventions can be highly effective in improving developmental outcomes. Evidence-based early interventions include Applied Behavior Analysis (ABA), developmental social-pragmatic interventions such as the Early Start Denver Model, and parent-mediated treatments.
Behavioral based therapies, particularly ABA, teach functional skills through reinforcement. Learning models of development highlight social interaction and learning in context. In schools, Individualized Education Programs (IEPs) design academic and social support that focuses on inclusion and generalization of skills.
Because of difficulty with communication, speech language therapy frequently serves the purpose of enhancing expressive and receptive language. Augmentative and Alternative Communication (AAC) devices like picture exchange or speech-generating devices are used to assist children who are nonverbal or minimally verbal.
Occupational therapy addresses daily living skills (e.g., dressing, feeding) and sensory processing differences. Sensory integration techniques aim to modulate responses to tactile, auditory, or vestibular input, but the quality of evidence is mixed.
There are no drugs that treat the core symptoms of ASD. Pharmacotherapeutically, however, co-morbid conditions may be addressed:
SSRIs: SSRIs are occasionally used for anxiety or repetitive behaviors, and the benefits that they provide vary and aren’t consistent.
Irritability and aggression in children is alleviated by risperidone and aripiprazole [^2].
ADHD symptoms can be relieved with a stimulant or non-stimulant.
Some families try diet changes (eg, gluten-casein–free diets), dietary supplements, or neural-feedback. Evidence is lacking for the majority of complementary modalities and underscoring the need for cautious, evidence-based guidance.
One thing with treatment planning for ASD: if something works for one person, it might not work for another. Individualized approaches, guided by genotype–phenotype correlations and the presence of comorbidities, are necessary but are in the early stage of development.
Early identification and service provision continue to lag. Diagnoses for kids in rural or underserved areas lag behind those for their urban peers by as much as three years. There are also racial and socioeconomic disparities that contribute to limited access to quality care and early intervention.
While services for autistic children have been growing, those for adults with ASD lag behind. Employment rate is low and feelings around mental health, like anxiety and depression, are widespread. Lifespan perspectives, with its focus on vocational training, housing and social support, is key but underresourced.
Public awareness of autism has grown and will continue to grow, but misconceptions persist — from discredited vaccine theories to the stereotype of “intellectual genius.” Promoting accurate neurodiversity affirming narratives is essential to reducing stigma and promoting inclusion.
Ongoing research is seeking objective biomarkers (e.g., EEG/clinical patterns, metabolomic profiles) to augment behavioral assignment behavioral diagnosis. Precision medicine strategies seek to tailor interventions to each person’s biological profiles.
Digital told — including virtual reality social skills training and AI language apps — provide scalable, engaging platforms for therapy. Telehealth has extended the reach of services, particularly in underserved geographies, though long-term data on effectiveness are still coming out.
Long term studies following individuals from childhood into older adulthood will provide insight on pathways of adaptive functioning and comorbidities. Cross-cultural research will help identify universal and culture-specific aspects of ASD, and guide tailored interventions around the world.
Advocacy has spurred legislative gains (e.g., insurance coverage of autism services), but comprehensive policies concerning adult services, inclusive education, and workplace accommodations are still priorities. Partnerships among researchers, clinicians, self-advocates, and policymakers can have potential for creating real change.
Autism Spectrum Disorder emphasizes the difficulties and possibilities of understanding neurodiversity. Advances in genetics and neurobiology, and new approaches to early identification and intervention, have changed the prospects for many autistic people. But persistent gaps, in personalized care, equitable access and adult supports — call for continued research, policy innovation and community engagement. By embracing the complexity of ASD and endorsing neurodiversity-affirming strategies, we can continue to improve quality of life and societal inclusion for individuals with autism throughout their life.
Citation Sheet
[^1] “Autism Spectrum Disorder: A Review.” JAMA Network, 2024, https://jamanetwork.com/journals/jama/fullarticle/2800182.
[^2] Shaw, Kelly A., et al. “Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years—Autism and Developmental Disabilities Monitoring Network, 16 Sites, United States, 2022.” MMWR Morbidity and Mortality Weekly Report, vol. 74, no. SS-2, April 2025, pp. 1–22, https://www.cdc.gov.
[^6] American Psychological Association. “Autism Spectrum Disorder.” APA Dictionary of Psychology, 2024, https://www.apa.org/topics/autism-spectrum-disorder.