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Autism
Spectrum Disorder

A neurodevelopmental condition characterized by persistent differences in social communication, restricted interests, repetitive behaviors, and atypical sensory processing. Presents across a spectrum of support needs.

  • 1 in 31
    Prevalence
  • ~18mo
    Onset Age
  • 3.4:1
    Ratio

DSM-5-TR Diagnostic Criteria

  • Criterion A: Social Communication & Interaction Deficits

    Persistent deficits across multiple contexts. All three required:

    • • Social-Emotional Reciprocity (Abnormal social approach, reduced sharing of interests/emotions, failure to initiate/respond to social interactions)
    • • Nonverbal Communication (Poorly integrated verbal/nonverbal communication, abnormal eye contact and body language, deficits in understanding/using gestures)
    • • Relationships (Difficulty adjusting behavior to social contexts, challenges in sharing imaginative play, difficulty making friends, absence of interest in peers)

  • Criterion B: Restricted, Repetitive Behaviors

    2+ required:

    • • Stereotyped/Repetitive Motor Movements or Speech (Hand flapping, rocking, echolalia, idiosyncratic phrases)
    • • Insistence on Sameness (Inflexible routines, ritualized patterns, extreme distress at changes)
    • • Highly Restricted, Fixated Interests (Abnormal in intensity or focus)
    • • Atypical Sensory Responses (Hyper/hypo-reactivity, unusual sensory interests, adverse response to textures/sounds)

  • Criterion C & D: Development & Function

    Onset and impact requirements:

    • • Criterion C: Symptoms must be present in early childhood
    • • Criterion D: Symptoms cause clinically significant impairment in social, occupational, or other areas

  • Specifiers

    Additional diagnostic information:

    • • With or without intellectual impairment
    • • With or without language impairment
    • • Associated with known genetic/medical condition
    • • Level of support required (Level 1, 2, or 3)

Assessment Protocols

Validated tools for screening and severity tracking

  • ADOS-2

    Autism Diagnostic Observation Schedule, Second Edition

    Criterion-standard semi-structured assessment using standardized activities to observe social-communication and restricted/repetitive behaviors.

    Scoring:

    Comparison scores (1-10); scores ≥8 suggest autism, 4-7 autism spectrum; module selected by age/language level

    Time:40-60 minutes

  • ADI-R

    Autism Diagnostic Interview-Revised

    Detailed parent/caregiver interview covering developmental history and current behaviors; complements ADOS-2.

    Scoring:

    Algorithm scores for social interaction, communication, and restricted/repetitive behaviors

    Time:90-150 minutes

  • M-CHAT-R/F

    Modified Checklist for Autism in Toddlers, Revised with Follow-Up

    Parent questionnaire for screening toddlers (16-30 months); includes follow-up interview to reduce false positives.

    Scoring:

    Low, medium, high risk based on critical items; high risk warrants immediate diagnostic evaluation

    Time:5 minutes (screener), 5-10 minutes (follow-up)

  • SRS-2

    Social Responsiveness Scale, Second Edition

    Quantitative measure of autistic traits across social awareness, cognition, communication, motivation, and restricted/repetitive behaviors.

    Scoring:

    T-scores: ≥76 severe, 66-75 moderate, 60-65 mild deficits in social interaction

    Time:15-20 minutes

Causes & Etiology

  • Neurobiological

    • Atypical brain connectivity (reduced long-range, increased local)
    • Brain volume changes in early childhood
    • Abnormalities in temporal cortex, amygdala, cerebellum
    • Altered excitatory/inhibitory (E/I) balance

  • Genetic

    • Heritability: 70-90%
    • Polygenic architecture: 100+ genes
    • De novo mutations (SHANK3, NLGN, NRXN)
    • Copy number variants (16p11.2 deletion, 15q duplication)

  • Environmental

    • Advanced parental age
    • Prenatal exposure to valproate
    • Maternal immune activation
    • Extreme prematurity and low birth weight

  • Neuropsychological

    • Theory of Mind deficits
    • Weak central coherence
    • Executive function impairments
    • Atypical sensory processing

Common Comorbidities

  • Intellectual Disability

    30-50%

    Ranges from mild to profound; significantly impacts adaptive functioning and treatment planning

  • ADHD

    ~28%

    Pooled estimate; higher in clinical samples; dual diagnosis allowed since DSM-5

  • Anxiety Disorders

    ~20%

    Pooled estimate, higher in clinical samples; OCD about 9%; sensory and predictability needs can contribute

  • Epilepsy/Seizure Disorders

    ~10%

    About 21% with intellectual disability vs 8% without; refer for neurological assessment if suspected

  • Gastrointestinal Issues

    Common

    Chronic constipation, diarrhea, abdominal pain; may affect behavior and communication

  • Sleep Disorders

    13% diagnosed

    Sleep problems are reported far more often than diagnosed sleep-wake disorders; insomnia and irregular sleep-wake patterns common

Evidence-Based Treatments

  • Applied Behavior Analysis (ABA)

    First-line

    Intensive behavioural intervention using reinforcement principles to teach communication, social, adaptive, and academic skills.

    Evidence

    Low-quality evidence of IQ and adaptive behaviour gains with early intensive programs (20-40 hrs/week)

    In practice

    Naturalistic developmental approaches (e.g., PRT, ESDM) emphasize child-led play

  • Speech-Language Therapy

    First-line

    Targets expressive/receptive language, pragmatic communication, and use of augmentative/alternative communication (AAC) if nonverbal.

    Evidence

    Supports communication development; earlier support is associated with better language outcomes

    In practice

    Coordinate with schools; may use visual supports, PECS, or speech-generating devices

  • Occupational Therapy

    First-line

    Addresses sensory processing difficulties, fine/gross motor skills, self-care, and adaptive functioning.

    Evidence

    May improve daily living skills and sensory-related distress; evidence quality is mixed

    In practice

    Sensory integration therapy controversial; focus on functional outcomes

  • Social Skills Training

    Adjunct

    Group or individual instruction in perspective-taking, conversation skills, emotional recognition, and friendship development.

    Evidence

    Moderate evidence for skill acquisition; generalization remains challenge

    In practice

    Structured programs (e.g., PEERS, Secret Agent Society) show promise

  • Medication (Targeted Symptoms)

    Adjunct

    Risperidone/aripiprazole (FDA-approved for irritability/aggression), SSRIs (anxiety/OCD), stimulants (ADHD), melatonin (sleep).

    Evidence

    No medication treats core autism symptoms; targets comorbid conditions and interfering behaviors

    In practice

    Careful monitoring; autistic individuals may have atypical medication responses

  • Parent/Caregiver Training

    Essential

    Teaches families to implement ABA principles, use visual supports, manage challenging behaviors, and promote generalization.

    Evidence

    Parent training reduced disruptive behaviour vs parent education in a large RCT (RUBI)

    In practice

    Parent-mediated programs (e.g., Project ImPACT) have a growing evidence base

Try it with one client

Send a PHQ-9 or GAD-7 by secure link and read the scored result before the session.

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Autism Spectrum Disorder questions

  • What is Autism Spectrum Disorder?

    Autism Spectrum Disorder (ASD) is a neurodevelopmental condition defined in DSM-5-TR (ICD-10 code F84.0) by persistent differences in social communication and interaction across multiple contexts, accompanied by restricted, repetitive patterns of behavior, interests, or activities. Atypical sensory processing is a recognized feature. Symptoms must be present in early developmental period and produce clinically significant impairment. Severity is rated across three levels reflecting the degree of support needed.

  • What are the symptoms of autism?

    Core symptoms span two DSM-5-TR criteria domains. Social communication differences include challenges with social-emotional reciprocity, nonverbal communication (eye contact, gestures, facial expressions), and developing or maintaining relationships. Restricted, repetitive behaviors include stereotyped motor movements (hand flapping, rocking), insistence on sameness, highly restricted fixated interests, and atypical sensory responses (hypersensitivity or hyposensitivity to sounds, textures, lights). Many autistic individuals also have differences in language development, cognitive profiles, and co-occurring conditions like ADHD or anxiety.

  • How is autism diagnosed?

    Diagnosis is made by a trained clinician (developmental pediatrician, child psychiatrist, neuropsychologist, or psychologist) using DSM-5-TR criteria informed by structured assessment. The ADOS-2 (Autism Diagnostic Observation Schedule) is the criterion-standard observational measure; the ADI-R (Autism Diagnostic Interview-Revised) is the parent interview companion. M-CHAT-R/F is the standard early childhood screener (16 to 30 months). Diagnostic workup typically includes developmental history, direct observation, cognitive and language assessment, and ruling out hearing impairment or other conditions.

  • What causes autism?

    Autism has a strong genetic basis, with heritability estimates of 80 to 90 percent. Hundreds of genes are implicated, including SHANK3, MECP2, and FMR1, with both common variants and rare de novo mutations contributing. Neurobiological models propose atypical neural connectivity, with increased local and reduced long-range connectivity in cortical networks. Environmental contributors include advanced parental age, prenatal valproate exposure, and certain pregnancy and birth complications. Vaccines do not cause autism; large studies have consistently found no link.

Scientific Sources

Evidence-Based

  • ADOS-2 Validation

    Lord C, Rutter M, et al. Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) Manual. Western Psychological Services. 2012.

  • DSM-5-TR Criteria

    American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). 2022.

  • Early Intensive Behavioural Intervention

    Dawson G, Rogers S, et al. Randomized, controlled trial of an intervention for toddlers with autism: the Early Start Denver Model. Pediatrics. 2010;125(1):e17-23.

  • Genetic Architecture of Autism

    Grove J, Ripke S, et al. Identification of common genetic risk variants for autism spectrum disorder. Nat Genet. 2019;51(3):431-444.

  • Neurobiology of Autism

    Geschwind DH, Levitt P. Autism spectrum disorders: developmental disconnection syndromes. Curr Opin Neurobiol. 2007;17(1):103-111.

  • M-CHAT-R/F Screening Tool

    Robins DL, Casagrande K, et al. Validation of the Modified Checklist for Autism in Toddlers, Revised with Follow-up (M-CHAT-R/F). Pediatrics. 2014;133(1):37-45.