Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition defined by two core domains: persistent deficits in social communication and social interaction, and restricted, repetitive patterns of behaviour, interests, or activities. DSM-5-TR classifies it under Neurodevelopmental Disorders. The term "spectrum" reflects wide variation in symptom severity, intellectual ability, and functional level - from individuals who need full-time support to those who live independently with minimal accommodation. References: DSM-5-TR, StatPearls (NCBI Bookshelf).

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition defined by two core domains: persistent deficits in social communication and social interaction, and restricted, repetitive patterns of behaviour, interests, or activities. DSM-5-TR classifies it under Neurodevelopmental Disorders. The term "spectrum" reflects wide variation in symptom severity, intellectual ability, and functional level - from individuals who need full-time support to those who live independently with minimal accommodation. DSM-5 merged previously separate diagnoses (autistic disorder, Asperger syndrome, pervasive developmental disorder-not otherwise specified) into a single ASD diagnosis with severity specifiers. ASD is a lifelong condition present from early development, though symptoms may not become fully apparent until social demands exceed capacity. It is not caused by vaccines, parenting style, or psychological trauma. Current CDC prevalence stands at approximately 1 in 36 children. This information is for psychoeducation only.

Domain A - Social communication and interaction deficits (all three subcriteria required for diagnosis): (1) Deficits in social-emotional reciprocity: The individual may not spontaneously share enjoyment, interests, or achievements (e.g., not showing or bringing objects to others, not pointing to share interest). There is often failure to initiate social interaction or to respond appropriately to others' attempts to engage (e.g., one-sided conversation, not answering when called by name). Social approach may be abnormal: standing too close or too far, speaking in a monotone or with unusual prosody, or making comments that do not fit the context. Back-and-forth conversation is reduced: the person may lecture on a favourite topic, give overly literal answers, or not ask reciprocal questions. In young children: limited or absent social smiling, reduced response to peek-a-boo, little interest in other children, not bringing toys to show parents. (2) Deficits in nonverbal communicative behaviours: Verbal and nonverbal communication are poorly integrated (e.g., saying "yes" while shaking head "no"). Eye contact may be absent, fleeting, or unusually intense/staring. Body language is limited or odd: little use of gestures to communicate (waving, pointing, nodding), flat or incongruent facial expressions, unusual posture or body orientation. Understanding of others' gestures and tone of voice is impaired (e.g., missing sarcasm, taking figurative language literally). In young children: delayed or absent pointing to request or share (protodeclarative and protoimperative pointing), limited use of gaze to check others' reactions, not following a point.

(3) Deficits in developing, maintaining, and understanding relationships: Behaviour does not adjust to social context (e.g., same style with peers, teachers, and strangers). There is difficulty understanding social rules, friendship boundaries, and what behaviour is expected in different settings. Shared imaginative play is reduced or absent: may engage in repetitive play scripts alone rather than cooperative pretend play. Making and keeping friends is difficult; the person may desire friendships but lack the skills, or show little apparent interest in peers. Understanding of relationships (e.g., different roles of parent vs. friend vs. stranger) may be limited. In adolescents and adults: difficulty with romantic relationships, reading social cues in dating, or navigating workplace social norms. Domain B - Restricted, repetitive patterns of behaviour, interests, or activities (at least two of four required): (1) Stereotyped or repetitive motor movements, object use, or speech: Motor stereotypies include hand flapping, finger flicking, body rocking, spinning, toe walking, and complex whole-body movements. Object use may be repetitive: lining up toys, spinning wheels, opening and closing doors. Speech patterns include echolalia (immediate or delayed repetition of others' words), scripted speech (repeating lines from videos or books), pronoun reversal, idiosyncratic or neologistic phrases, and unusual prosody (flat, sing-song, or robotic). Some individuals have verbal rituals (e.g., repeating a phrase a set number of times before continuing). (2) Insistence on sameness, inflexible adherence to routines, ritualised patterns: Small changes can cause extreme distress (e.g., a different route to school, a change in furniture placement). There may be rigid thinking ("we always do it this way") and difficulty with transitions. Daily routines become ritualised: same foods, same order of activities, same clothing. Anxiety or meltdowns occur when routines are disrupted. Questions may be asked repeatedly to gain predictability. Some individuals insist on strict rules and become upset when others do not follow them. (3) Highly restricted, fixated interests abnormal in intensity or focus: Preoccupation with narrow topics (e.g., train schedules, dinosaurs, a specific TV character, numbers, maps) that dominate conversation and time. The interest may be longstanding and unusually intense compared with typical hobbies. Unusual attachments to objects (e.g., carrying a specific item everywhere). In older individuals, interests may appear more "normal" (e.g., computers, science) but the intensity and one-sidedness remain. Difficulty shifting attention away from the interest when required. (4) Hyper- or hypo-reactivity to sensory input or unusual sensory interests: Hyperreactivity (over-responsiveness): distress or avoidance of everyday sounds (vacuum, hand dryers, chewing), textures (tags in clothing, certain foods, sticky substances), lights, or smells; covering ears, gagging, or fleeing. Hyporeactivity (under-responsiveness): apparent indifference to pain or temperature, high pain threshold, not responding to name being called, seeking intense movement (spinning, jumping). Unusual sensory interests: excessive smelling or touching of objects or people, visual fascination with lights or spinning objects, mouthing non-food items, seeking deep pressure or tight clothing. These patterns contribute to restricted diets, clothing preferences, and avoidance of crowded or noisy environments. Additional features commonly seen (not required for diagnosis): Language delay or disorder in ~25-30%; ~25% remain nonverbal or minimally verbal. Motor: clumsiness, poor coordination, unusual gait, difficulty with handwriting. Eating:

strong food preferences, texture aversions, ARFID (avoidant/restrictive food intake). Sleep: ~50-80% have difficulty falling asleep, staying asleep, or early waking. GI: constipation, diarrhoea, abdominal pain in ~30-50%. Behavioural: meltdowns or shutdowns when overwhelmed by sensory input, change, or social demands; these are often misinterpreted as "tantrums" but reflect overload. Emotional dysregulation and anxiety are very common.

Genetic: heritability estimated at ~80% from twin studies; concordance rate ~77% for monozygotic twins vs. ~31% for dizygotic twins. Family history of ASD increases risk ~10 fold for siblings; broader autism phenotype (subclinical traits) present in ~20% of first-degree relatives. Over 100 genes implicated, including SHANK3, CHD8, SCN2A, NRXN1, and PTEN. Sex: male:female ratio approximately 4:1. Females may be underdiagnosed due to "camouflaging" - consciously masking social difficulties to fit in. Females more often present with internalising symptoms and fewer overt repetitive behaviours. Prenatal/perinatal: advanced parental age (both maternal and paternal, risk increases ~5-10% per 10-year increase); valproic acid exposure in utero (risk increased ~3-5 fold); maternal infections (rubella, CMV) during pregnancy; gestational diabetes; maternal obesity; extreme prematurity (<26 weeks); low birth weight. Copy number variants (CNVs): deletions and duplications at 16p11.2, 15q11-13, and 22q11.2 each account for ~1% of ASD cases. Vaccines do NOT cause ASD. Multiple large-scale epidemiological studies (total sample sizes exceeding 1 million children) have conclusively refuted any link between vaccines (including MMR) and ASD.

ASD has a strongly genetic basis but is aetiologically heterogeneous. About 10-20% of ASD cases have a known genetic cause: single-gene disorders (Fragile X syndrome accounts for ~2-3% of ASD; tuberous sclerosis complex for ~1-4%; Rett syndrome; PTEN hamartoma syndrome); chromosomal abnormalities (Down syndrome, 22q11.2 deletion); and de novo mutations (present in ~10% of simplex cases). The remaining ~80-90% involve polygenic risk: hundreds of common variants each contribute small effects. GWAS studies have identified risk loci near genes involved in synaptic function (synapse formation, neurotransmitter signalling) and chromatin remodelling (gene regulation during brain development). Neurobiologically, ASD involves atypical development of cortical connectivity. Early brain overgrowth in the first 2 years of life (enlarged head circumference, increased cortical surface area) is followed by a plateau, potentially reflecting excess local connectivity and reduced long-range connectivity. The "intense world" theory proposes that hyperreactive neural circuits produce overwhelming sensory/emotional experiences, driving social withdrawal. Neurotransmitter findings: elevated blood serotonin (hyperserotonemia) in ~25-30% of individuals with ASD; disrupted GABAergic inhibitory signalling; altered oxytocin/vasopressin systems (implicated in social behaviour). No single neurotransmitter deficit explains ASD.

CDC ADDM Network (2023): prevalence of ASD among 8-year-olds is approximately 1 in 36 (2.8%), up from 1 in 150 in

in girls, minority children, and those without intellectual disability. Sex ratio: ~3.8:1 male:female in children. The ratio drops with co-occurring intellectual disability (closer to 2:1), suggesting that ASD in females is more often recognised when accompanied by cognitive impairment. Intellectual ability: ~33% of individuals with ASD have co-occurring intellectual disability (IQ <70); ~25% are nonverbal or minimally verbal; ~44% have average or above-average intelligence. Racial/ethnic distribution: ASD is now diagnosed at similar rates across racial and ethnic groups in the USA, though historically Black and Hispanic children were diagnosed later and less often. Socioeconomic disparities in age of diagnosis persist. Co-occurring conditions: ADHD (~30-60%); anxiety disorders (~40-50%); epilepsy (~20-30%, higher with intellectual disability); depression (~12-70% of adults); sleep disorders (~50-80%); GI problems (~30-50%). Global prevalence estimates range from ~0.4% to >2% depending on country and methodology.

Cognitive theories: (1) Theory of mind (ToM) deficit: difficulty inferring others' mental states, intentions, and emotions. Tests such as the Sally-Anne task demonstrate this in children with ASD as young as age 4. (2) Weak central coherence: preference for local/detail-focused processing over global/gestalt processing - explaining both strengths (pattern detection, systemising) and difficulties (missing the "big picture" in social contexts). (3) Executive dysfunction: impaired cognitive flexibility, planning, and working memory, overlapping with ADHD symptoms. Neuroanatomy: early brain overgrowth (total brain volume ~5-10% larger than controls in ages 2-4) followed by normalisation or slight reduction by adolescence. The amygdala shows early enlargement, potentially contributing to social anxiety and avoidance. The fusiform face area shows reduced activation during face processing. Reduced Purkinje cell count in the cerebellum is one of the most replicated post-mortem findings. Connectivity: DTI studies show altered white matter integrity in the superior longitudinal fasciculus, uncinate fasciculus, and corpus callosum - tracts connecting frontal, temporal, and parietal regions involved in social cognition and language. The "underconnectivity" theory proposes that reduced long-range cortical-cortical connections impair integration of complex social and linguistic information. Neuroinflammation: microglial activation and elevated pro-inflammatory cytokines (IL-6, TNF-alpha) have been found in post-mortem brain tissue and cerebrospinal fluid of individuals with ASD.

regions. This can affect how information is integrated: the brain may focus very well on details and patterns but have more difficulty combining social cues (faces, tone of voice, body language) into a coherent picture. The amygdala (involved in emotional and social processing) may be enlarged or overactive, contributing to anxiety and sensory sensitivity. Brain regions involved in understanding others' thoughts and feelings ("theory of mind") can show reduced activation. ASD is strongly genetic and present from early development; it is not caused by vaccines or parenting. These brain differences are part of who the person is; supports and therapies aim to help them thrive with their unique wiring.

Developmental surveillance at every well-child visit. The AAP recommends ASD-specific screening at 18 and 24 months using the Modified Checklist for Autism in Toddlers, Revised with Follow-Up (M-CHAT-R/F). Red flags triggering immediate evaluation: no babbling by 12 months; no pointing or gesturing by 12 months; no single words by 16 months; no 2-word spontaneous phrases by 24 months; loss of previously acquired language or social skills at any age. Comprehensive diagnostic evaluation includes: (1) Detailed developmental history from caregivers, covering social communication milestones, play patterns, and repetitive behaviours across settings. (2) Direct behavioural observation using standardised tools (ADOS-2). (3) Cognitive/developmental testing (Mullen Scales, Bayley-III, or Wechsler scales depending on age and ability). (4) Adaptive behaviour assessment (Vineland-3). (5) Speech-language evaluation. (6) Sensory profile assessment. Physical exam: measure head circumference (macrocephaly in ~15-20%); check for dysmorphic features suggesting a genetic syndrome; Wood's lamp for hypopigmented macules (tuberous sclerosis); neurological exam for hypotonia, motor stereotypies, and gait abnormalities.

DSM-5-TR criteria: (A) Persistent deficits in social communication and social interaction across multiple contexts, manifested by all three subcriteria (social-emotional reciprocity, nonverbal communication, relationships). (B) Restricted, repetitive patterns of behaviour, interests, or activities, manifested by >=2 of four subcriteria. (C) Symptoms present in the early developmental period (though may not manifest fully until social demands exceed limited capacities, or may be masked by learned strategies). (D) Symptoms cause clinically significant impairment in current functioning. (E) Not better explained by intellectual disability or global developmental delay (though the two frequently co-occur). Severity levels: Level 1 - "requiring support" (can speak in full sentences but has difficulty initiating social interactions; inflexibility causes significant interference); Level 2 - "requiring substantial support" (marked deficits in verbal and nonverbal social communication; restricted interests are obvious to casual observers); Level 3 - "requiring very substantial support" (severe deficits in verbal and nonverbal communication; very limited initiation and minimal response to social overtures). Specifiers: with or without accompanying intellectual impairment; with or without accompanying language impairment; associated with a known medical/genetic condition or environmental factor; associated with another neurodevelopmental, mental, or behavioural disorder; with catatonia. ICD-11 code: 6A02. ICD-11 similarly consolidates prior subtypes into a single spectrum diagnosis.

Gold-standard diagnostic instruments: the Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2) - a semi-structured, standardised assessment of communication, social interaction, play, and imagination, administered directly with the individual. The Autism Diagnostic Interview-Revised (ADI-R) - a structured caregiver interview covering early development, social communication, repetitive behaviours, and onset. Additional tools: Social Responsiveness Scale (SRS-2) - a 65-item rating scale measuring the severity of social communication deficits; Childhood Autism Rating Scale (CARS-2) - clinician-rated; Repetitive Behavior Scale-Revised (RBS-R). Medical workup for aetiology: chromosomal microarray analysis (CMA) is the first-tier genetic test, identifying clinically significant CNVs in ~10% of cases. Fragile X DNA testing (FMR1 gene). Whole exome sequencing when CMA is unrevealing and dysmorphic features or intellectual disability are present. Metabolic testing if regression, seizures, or specific clinical features suggest an inborn error of metabolism. EEG if seizures are suspected (~20-30% of individuals with ASD have epilepsy). Lead screening. Hearing assessment to rule out hearing loss as a contributor to communication delay.

Social (Pragmatic) Communication Disorder: social communication deficits without restricted/repetitive behaviours. This diagnosis cannot be given if ASD criteria are met. Language disorders: specific language impairment or mixed receptive-expressive language disorder can mimic the communication component but lack the restricted/repetitive behaviour domain. Intellectual Disability: social communication may be impaired in proportion to cognitive level; ASD requires social communication below that expected for general developmental level. ADHD: inattention and impulsivity may impair social functioning, but the social motivation and theory of mind deficits in ASD are qualitatively different. ASD and ADHD can be co-diagnosed (permitted since DSM-5). Reactive Attachment Disorder: arises from severe early neglect; social approach and attachment behaviour improve with appropriate caregiving, unlike ASD. Selective Mutism: social withdrawal limited to specific settings; the child communicates normally in comfortable environments. Schizophrenia: hallucinations and delusions are not features of ASD; onset of psychosis is typically in late adolescence/adulthood. Social anxiety disorder: avoidance stems from fear of negative evaluation, not from difficulty processing social cues. Obsessive-compulsive disorder: repetitive behaviours in OCD are ego-dystonic (unwanted), while those in ASD are typically ego-syntonic (comforting or preferred).

Treatment of Autism Spectrum Disorder (ASD) is multidisciplinary and individualised, focusing on improving functional abilities, reducing core symptom impact, and supporting quality of life across the lifespan. Applied Behaviour Analysis (ABA): ABA is the most extensively studied behavioural intervention for ASD. It applies principles of learning (reinforcement, prompting, shaping, generalisation) to increase adaptive behaviours and reduce those that interfere with learning or safety.

Key approaches within ABA include: (1) Discrete Trial Training (DTT): skills are broken into small steps, taught in structured trials with clear antecedents and consequences; often used for early language, imitation, and academic readiness. (2) Naturalistic teaching (incidental teaching, natural environment teaching): instruction is embedded in play and daily routines, with the child's motivation driving teaching opportunities; promotes generalisation. (3) Verbal Behaviour (VB) approach: based on Skinner's analysis of language; teaches communication by function (manding/requesting, tacting/labeling, intraverbals/conversation). (4) Pivotal Response Treatment (PRT): targets "pivotal" areas (motivation, response to multiple cues, self-management, social initiations) so that improvement in these produces broad collateral gains. (5) Early Start Denver Model (ESDM): a naturalistic developmental behavioural intervention for toddlers/preschoolers; combines ABA with developmental, relationship-based approaches in play-based sessions. Early Intensive Behavioural Intervention (EIBI), typically 20-40 hours per week of one-to-one ABA started before age 4, has been shown in multiple studies to produce gains in IQ, language, and adaptive behaviour (e.g., Vineland scores) in many children; effect sizes are largest when intervention starts early and is delivered with fidelity. ABA is also used to address challenging behaviour (functional behaviour assessment and behaviour support plans), self-care skills, and social skills. Duration and intensity are individualised; some children benefit from 15-25 hours weekly, others from more intensive programmes. Note: some autistic adults have raised concerns about historical ABA practices (e.g., suppressing stimming, rigid compliance training); contemporary ABA increasingly emphasises assent, naturalistic contexts, and quality-of-life outcomes. Occupational Therapy (OT): OT for ASD focuses on participation in daily activities (activities of daily living, education, play, social participation) by addressing sensory processing, motor skills, and self-regulation. Assessment typically includes: sensory profiles (e.g., Sensory Profile-2, Adolescent/Adult Sensory Profile) to identify over- and under-responsivity, seeking, and registration patterns; fine and gross motor testing; and observation of self-care (dressing, feeding, grooming, toileting). Intervention goals often include: (1) Fine motor and visual-motor skills: handwriting, cutting, manipulation of small objects, bilateral coordination; (2) Gross motor skills: balance, coordination, motor planning (praxis), participation in PE and play; (3) Self-care: breaking down dressing, feeding, and toileting into teachable steps; use of visual schedules and adaptive equipment; (4) Adaptive functioning: organisation, sequencing, time management, and independence in routines. OT is delivered in clinic, school, or home; frequency is typically 1-2 sessions per week with carryover activities for families. Evidence supports OT for improving motor outcomes and participation; effects on sensory-related behaviours are reported but study quality varies. Sensory Integration (SI) Therapy: Sensory integration, as developed by A. Jean Ayres, refers to the brain's ability to organise and interpret sensory input (tactile, vestibular, proprioceptive, visual, auditory) for adaptive responses. Many autistic individuals show differences in sensory processing: over-responsivity (e.g., distress to sounds or textures), under-responsivity (e.g., high pain threshold, seeking intense input), or sensory seeking (e.g., spinning, crashing, chewing). Sensory integration therapy is typically delivered by OTs trained in Ayres Sensory Integration (ASI). It takes place in a specially equipped gym with equipment such as swings, crash pads, tactile bins, and climbing structures. Sessions are child-directed: the therapist offers sensory-rich activities that challenge the child's ability to integrate input and respond adaptively, with the goal of improving sensory processing, self-regulation, and participation.

A "sensory diet" (individualised schedule of sensory activities throughout the day) may be used at home and school to help maintain regulation. Evidence: some randomised trials and systematic reviews report positive effects of SI therapy on outcomes such as socialisation, behaviour, and sensory processing; other reviews note limited or inconsistent evidence. Many families and clinicians report subjective benefit; individual response varies. Alternatives or adjuncts include: environmental modifications (reducing noise, offering quiet spaces, weighted blankets with caution), accommodations at school (e.g., movement breaks, fidget tools), and teaching self-advocacy for sensory needs. Speech and Language Therapy: Targets communication development, including augmentative and alternative communication (AAC) - picture exchange communication systems (PECS), speech-generating devices, sign language - for nonverbal or minimally verbal individuals. Pragmatic language intervention addresses social communication difficulties such as conversational turn-taking, topic maintenance, and understanding figurative language. Co-occurring Depression: Depression is one of the most common co-occurring mental health conditions in autistic individuals. Prevalence estimates in adults with ASD range from ~12% to ~70% (higher in clinic samples and those without intellectual disability). Depression is often underdetected because: (1) Atypical presentation - autistic individuals may show more irritability, agitation, withdrawal, or regression in skills rather than clearly stated low mood; (2) Overlap with ASD traits - reduced social motivation, flat affect, and withdrawal can be attributed to ASD; (3) Communication difficulties - some individuals cannot easily describe internal states; (4) Camouflaging - effort to appear "normal" may mask distress until burnout or crisis. Risk factors for depression in ASD include: social isolation and bullying, unmet support needs, autistic burnout, co-occurring anxiety, and transition periods (e.g., leaving school, job loss). Screening: use of standard tools (e.g., PHQ-9, GAD-7) with awareness that items may need interpretation in light of ASD (e.g., "little interest" may reflect ASD profile). Ask directly about mood, sleep, energy, and suicidal ideation; involve caregivers when appropriate. Treatment: (1) Psychological - adapted CBT (e.g., addressing black-and-white thinking, social comparison, bullying; longer sessions, visual supports, concrete examples) and mindfulness-based approaches have some support; (2) Pharmacological - SSRIs (sertraline, fluoxetine, escitalopram) are first-line; start low, go slow; monitor for activation or increased anxiety (autistic individuals may be more sensitive). No medication is FDA-approved specifically for depression in ASD. (3) Environmental - reduce overload, support rest, address bullying or unmet needs. Suicidality: autistic adults have elevated rates of suicidal ideation and suicide attempts; assess routinely and ensure crisis resources are available. Pharmacotherapy (other): No medication treats the core social communication or restricted/repetitive behaviour features of ASD. Medications target co-occurring symptoms: Irritability and aggression: risperidone (FDA-approved for ASD-related irritability in ages 5-16; start 0.25mg, typical dose 0.5-3mg) and aripiprazole (FDA-approved for ASD-related irritability in ages 6-17; start 2mg, typical dose 5-15mg). Both carry metabolic side effects (weight gain, glucose elevation). ADHD symptoms: methylphenidate (response rate ~50% in ASD vs. ~70% in ADHD alone; higher side effect sensitivity); guanfacine; atomoxetine. Anxiety: SSRIs may help in adolescents and adults; evidence is weaker than in neurotypical anxiety. Sleep disturbance: melatonin (3-10mg at bedtime) improves sleep onset latency and total sleep time with an excellent safety profile.

Family Support: Parent training, respite care, sibling support, and connecting families with community resources and advocacy organisations are essential. Transition planning for adolescents and adults addresses employment, independent living, and ongoing support needs.

ASD is a lifelong condition. Outcomes vary enormously across the spectrum. Approximately 10-20% of individuals diagnosed in early childhood achieve "optimal outcome" (no longer meeting diagnostic criteria by late childhood or adulthood), typically those with higher initial IQ, early language development, and intensive early intervention. Among adults with ASD: ~15-20% live independently; ~25-40% live semi-independently with some support; ~40-60% require substantial daily support. Employment rates are low: only ~15-30% of autistic adults maintain competitive employment, making ASD one of the lowest employment-rate disability categories. Early intervention (before age 3-4) substantially improves long-term outcomes in language, adaptive behaviour, and IQ - with average gains of 15-20 IQ points in some EIBI studies. Higher IQ, functional language by age 5, and absence of co-occurring intellectual disability are the strongest positive prognostic indicators. Life expectancy is reduced by an estimated 16-20 years on average, driven by epilepsy-related mortality, accidents (especially drowning in children), and suicide in higher-functioning individuals. Autistic adults without intellectual disability have a suicide rate ~9 times higher than the general population.

Mental health: anxiety disorders (~40-50% prevalence across the lifespan); depression (~12-70% in adults, often underdetected due to atypical presentation); suicidality (estimated 30% of autistic adults experience suicidal ideation); eating disorders (especially ARFID - avoidant/restrictive food intake disorder, and anorexia nervosa in autistic females). Epilepsy: ~20-30% develop seizures, with peaks in early childhood and adolescence; risk is highest in those with co-occurring intellectual disability. Autistic burnout: chronic exhaustion, increased sensitivity, and loss of previously acquired skills from prolonged masking and coping demands, increasingly recognised as a distinct phenomenon. Sleep disorders: ~50-80% experience chronic sleep difficulties, affecting daytime functioning and behaviour. GI problems: constipation, diarrhoea, and abdominal pain in ~30-50%. Wandering/elopement: ~50% of children with ASD wander from safe settings; drowning is a leading cause of death in ASD children under 15. Social isolation and victimisation: children with ASD are bullied at 3-4 times the rate of neurotypical peers. Caregiver burden: parents of children with ASD report higher rates of depression, anxiety, and marital stress.

No primary prevention for ASD exists. Risk reduction: adequate folate supplementation before and during pregnancy; avoiding valproic acid during pregnancy when possible; managing gestational diabetes and maternal obesity. Genetic counselling is appropriate for families with a child with ASD, given the ~10-20% recurrence risk for subsequent siblings. Early detection is the single most impactful intervention. Screening at 18 and 24 months identifies children who benefit from early intervention during peak brain plasticity. Parents should be educated about developmental milestones and red flags.

Key messages for families: ASD is a neurodevelopmental condition, not caused by parenting or vaccines. It is a difference in brain development, not a disease to be cured. Many autistic individuals prefer identity-first language ("autistic person" rather than "person with autism"). Strengths - attention to detail, pattern recognition, honesty, and deep expertise in areas of interest - should be recognised alongside challenges. Evidence-based interventions (ABA, speech therapy, OT) produce meaningful gains, especially when started early. Co-occurring conditions (anxiety, ADHD, sleep problems, GI issues) are treatable and should be assessed. Community resources: parent training programmes, respite services, special education advocacy, adult services for supported employment and housing.

1911: Eugen Bleuler coined "autism" (from Greek autos, "self") to describe social withdrawal in schizophrenia. 1943: Leo Kanner described 11 children with "early infantile autism" - characterised by autistic aloneness, insistence on sameness, and language abnormalities. 1944: Hans Asperger independently described children with social deficits but normal or superior language and intelligence. 1960s-70s: Bruno Bettelheim's "refrigerator mother" theory falsely blamed cold parenting; this was debunked but caused lasting damage. 1980: DSM-III introduced "infantile autism" under Pervasive Developmental Disorders. 1994: DSM-IV included autistic disorder, Asperger disorder, Rett disorder, childhood disintegrative disorder, and PDD-NOS. 1998: Andrew Wakefield published a fraudulent study claiming a link between MMR vaccine and autism; the study was retracted in 2010 and Wakefield lost his medical licence. Multiple large studies involving over 1 million children found no vaccine-autism link. 2013: DSM-5 consolidated all subtypes into Autism Spectrum Disorder with severity levels, dropped Asperger syndrome as a separate diagnosis, and permitted co-diagnosis with ADHD.

The neurodiversity movement, originating in the late 1990s, frames autism as a natural variation in human neurology rather than a disorder to be cured. Many autistic self-advocates reject the idea that ASD needs "treatment" in the sense of elimination, while acknowledging that co-occurring conditions (anxiety, epilepsy, sleep problems) and specific skill deficits benefit from intervention. Language preferences are contested: many autistic adults prefer identity-first language ("autistic person"), viewing autism as inseparable from identity. Some parents and professionals prefer person-first language ("person with ASD"). Clinicians should ask and respect individual preferences. Organisations like the Autistic Self Advocacy Network (ASAN) advocate for inclusion, while parent-led organisations like Autism Speaks have shifted toward acceptance-based messaging. Controversies persist around ABA (some autistic adults describe historical ABA practices as harmful), functioning labels (the high/low-functioning binary oversimplifies), and the search for genetic "causes" (perceived by some as eugenics-adjacent). Employment discrimination and underemployment remain widespread. Several technology companies (SAP, Microsoft, Google) have launched autism hiring programmes targeting strengths in systemising, pattern recognition, and quality assurance. The estimated lifetime cost of supporting an individual with ASD ranges from $1.4 million (without intellectual disability) to $2.4 million (with intellectual disability) in the USA.

Genetics: whole genome sequencing studies continue to identify rare variants with large effects and common variants with small effects. The SPARK consortium (Simons Foundation) has enrolled >300,000 individuals for the largest ASD genetic study. Gene-therapy approaches targeting monogenic forms (e.g., Rett syndrome via MECP2 gene replacement) are in clinical trials. Biomarkers: eye-tracking studies detect reduced attention to social stimuli (faces, eyes) as early as 2-6 months of age, potentially enabling pre-symptomatic identification. EEG-based biomarkers (differences in event-related potentials to social stimuli) are under investigation. Machine learning applied to electronic health records identifies children at elevated ASD risk before clinical diagnosis. Pharmacotherapy: oxytocin intranasal trials have produced inconsistent results for social communication; bumetanide (a loop diuretic that shifts GABA from excitatory to inhibitory) showed modest benefit in some European trials but failed primary endpoints in larger studies. Arbaclofen (GABA-B agonist) and balovaptan (vasopressin V1a receptor antagonist) have been tested with mixed results. Intervention science: telehealth-delivered parent coaching (RUBI, Project ImPACT) has demonstrated effectiveness and expanded access in rural and underserved communities. AI-powered wearable devices (e.g., Superpower Glass) that provide real-time facial emotion recognition feedback to children with ASD are in development.

APA. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.; DSM-5-TR). APA Publishing. Sadock BJ, Sadock VA, Ruiz P. (Eds.). (2024). Kaplan & Sadock's Comprehensive Textbook of Psychiatry (11th ed.). Wolters Kluwer. StatPearls [Internet]. Autism Spectrum Disorder. NCBI Bookshelf. StatPearls Publishing. WHO. (2022). ICD-11 for Mortality and Morbidity Statistics. Geneva: World Health Organization. CDC ADDM Network. (2023). Prevalence and Characteristics of Autism Spectrum Disorder. MMWR.

StatPearls: https://www.ncbi.nlm.nih.gov/books/NBK525976/ CDC Autism: https://www.cdc.gov/autism/ NIMH Autism: https://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd Autistic Self Advocacy Network: https://autisticadvocacy.org SPARK for Autism (Simons Foundation): https://sparkforautism.org WHO ICD-11 code 6A02: https://icd.who.int Crisis: 988 (US Suicide & Crisis Lifeline); Text HOME to 741741 (Crisis Text Line) Note: Educational only. Not a substitute for professional care.