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N
Strong Evidence

Autism Assessment

Understanding what a proper autism assessment involves, the diagnostic criteria used, and what to expect from the process.

DSM-5-TR Diagnostic Criteria
The current international standard for autism diagnosis. ICD-11 criteria are similar.

Autism Spectrum Disorder diagnosis requires meeting criteria in both Domain A (social communication) and Domain B (restricted/repetitive patterns), plus additional requirements about timing and impairment.

Domain A: Social Communication & Interaction
Persistent deficits in social communication and social interaction across multiple contexts.

Social-emotional reciprocity

  • Difficulty with back-and-forth conversation
  • Reduced sharing of interests or emotions
  • Difficulty initiating or responding to social interactions

Nonverbal communication

  • Difficulty integrating verbal and nonverbal communication
  • Atypical eye contact and body language
  • Difficulties understanding and using gestures
  • Limited or atypical facial expressions

Relationships

  • Difficulty adjusting behaviour to social contexts
  • Difficulty sharing imaginative play or making friends
  • Reduced interest in peers

Must meet ALL 3 criteria

Domain B: Restricted, Repetitive Patterns
Restricted, repetitive patterns of behaviour, interests, or activities.

Stereotyped movements, speech, or object use

  • Motor stereotypies (hand flapping, spinning)
  • Echolalia (repeating words/phrases)
  • Idiosyncratic use of phrases
  • Lining up objects

Insistence on sameness

  • Distress at small changes
  • Rigid thinking patterns
  • Greeting rituals
  • Need to take same route

Highly restricted interests

  • Strong attachment to unusual objects
  • Excessively focused interests
  • Perseverative topics of conversation

Sensory reactivity

  • Apparent indifference to pain/temperature
  • Adverse response to specific sounds or textures
  • Excessive smelling or touching of objects
  • Visual fascination with lights or movement

Must meet at least 2 of 4 criteria

Additional diagnostic requirements

C

Symptoms present in early developmental period

May not fully manifest until social demands exceed capacity, or may be masked.

D

Symptoms cause clinically significant impairment

In social, occupational, or other important areas of current functioning.

E

Not better explained by intellectual disability or global developmental delay

Though autism and intellectual disability can co-occur.

Assessment tools

These are the main tools clinicians use. Not all will be used in every assessment.

ADOS-2
Direct assessment
Autism Diagnostic Observation Schedule, 2nd Edition

Gold-standard structured observation. Creates opportunities to observe social communication and play.

Highly trained administrator required. Not a "test" to pass or fail - it's an observation framework.

ADI-R
Parent interview
Autism Diagnostic Interview - Revised

Detailed structured interview covering developmental history and current functioning.

Takes 2-3 hours. Very thorough but time-intensive.

3Di
Parent interview
Developmental, Dimensional and Diagnostic Interview

Computerised structured interview covering autism symptoms and development.

Shorter than ADI-R. Often used in UK services.

DISCO
Parent interview
Diagnostic Interview for Social and Communication Disorders

Comprehensive interview that also assesses broader difficulties.

Good for complex presentations or when broader profile needed.

Note:

Screening is not diagnosis. Screening tools (M-CHAT, SCQ, online questionnaires) indicate who should be assessed further - they cannot diagnose autism. A positive screen means "consider assessment", not "has autism".

The assessment process

1

Referral

Initial concerns raised, referral accepted by assessment service.

Service reviews referral information, may request additional details, places on waiting list.

2

Information gathering

Questionnaires and background information collected.

Parents complete developmental history forms. School provides observations. Medical records reviewed.

3

Assessment appointment(s)

Direct assessment and interviews with clinician(s).

May be single session or multiple. Includes parent interview, observation/interaction with child.

4

Multidisciplinary discussion

Team reviews all information (in MDT models).

Different professionals share observations, reach consensus on diagnosis.

5

Feedback

Results shared with family.

Diagnosis explained, questions answered, next steps discussed.

6

Report

Written documentation provided.

Detailed report with history, findings, diagnostic conclusions, and recommendations.

Challenging presentations

Some autistic people are harder to diagnose. This doesn't mean they're "less autistic" - it means standard approaches may not capture their experience.

Girls and women

Challenges:

  • May camouflage/mask social difficulties
  • May have learned social scripts
  • Interests may be more typical (though intense)
  • Friendship difficulties may be subtle

Approach: Look beyond surface. Ask about effort required. Consider impact of masking.

High IQ / "high functioning"

Challenges:

  • May compensate with intelligence
  • Difficulties may emerge later (secondary school)
  • May be dismissed as "quirky but fine"
  • Often delayed diagnosis

Approach: Compare to cognitive peers. Look for hidden struggles. Consider internal experience.

Co-occurring ADHD

Challenges:

  • ADHD can mask autism features
  • Social difficulties attributed to impulsivity
  • Hyperactivity can obscure repetitive behaviours
  • Shared features complicate assessment

Approach: Assess both thoroughly. Consider staged assessment.

Language delay

Challenges:

  • Autism features may be attributed to language delay
  • Communication difficulties affect assessment
  • May need adapted assessment approaches

Approach: Use appropriate tools. Focus on nonverbal communication. Involve speech therapy.

The key insight

Autism assessment is clinical judgement, not a test. There's no blood test or brain scan for autism. Diagnosis is made by trained clinicians integrating information from multiple sources to form a clinical opinion.

A good assessment considers not just whether criteria are met, but how autism presents in your specific child, what support they need, and what their strengths are.