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Clinical Condition Guide

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 36
    Prevalence
  • ~18mo
    Onset Age
  • 4:1
    Ratio
  • 70-90%
    Response Rate

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

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.

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

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