Autism is a lifelong neurodevelopmental difference that influences how a person communicates, interacts with others, processes sensory information and experiences the world.
Because autism is a spectrum, it does not look the same in every person. Some Autistic people communicate through speech and live independently, while others use alternative communication and require extensive daily assistance. A person may also have significant needs in one area and fewer needs in another.
Understanding the diagnostic criteria and the three autism support levels can help families make sense of an assessment. However, these levels should never be used to define a person’s intelligence, personality, potential or value.
How Is Autism Diagnosed?
In Australia, autism assessments should follow a comprehensive and evidence informed process. Clinicians commonly refer to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision, known as the DSM 5 TR.
There is no blood test, brain scan or single questionnaire that can diagnose autism. An assessment may consider:
- Developmental and medical history
- Communication and social interaction
- Behaviour, routines and interests
- Sensory experiences
- Daily functioning
- Information from parents, caregivers, educators or partners
- Direct observation and standardised assessment tools
- Possible alternative or co occurring conditions
A qualified clinician uses professional judgement to determine whether the person meets all required criteria. A screening result or a collection of individual traits is not enough to confirm a diagnosis.
The Two Main Areas of the Diagnostic Criteria
The DSM 5 TR organises the central characteristics of autism into two areas.
Area A: Social Communication and Social Interaction
To meet the diagnostic criteria, differences must be present in all three of the following areas.
1. Social and emotional reciprocity
This refers to the natural exchange that occurs during social interaction.
A person may find it difficult to begin or maintain conversations, share interests, respond to another person’s emotions or participate in the usual back and forth flow of interaction.
This does not mean that Autistic people lack emotions or empathy. They may express interest, affection and concern in ways that others do not immediately recognise.
2. Nonverbal communication
A person may experience differences in eye contact, facial expressions, gestures, body language or the coordination of spoken and nonverbal communication.
Some people may use few gestures, while others may use learned expressions or eye contact that feels uncomfortable or requires considerable effort.
3. Developing and understanding relationships
This can include difficulty adjusting behaviour across different social settings, understanding unwritten social expectations, developing friendships or participating in imaginative and cooperative play.
The person may want relationships but find social situations confusing, tiring or unpredictable.
Area B: Restricted or Repetitive Patterns
A person must demonstrate characteristics in at least two of the following four areas.
1. Repetitive movement, speech or use of objects
Examples may include repeating words or phrases, arranging objects, rocking, hand movements or using toys in consistent ways.
Repetitive movement, sometimes called stimming, may help a person regulate emotions, express excitement or manage sensory input. Harmless stimming should not automatically be treated as a problem.
2. Preference for sameness and predictability
A person may rely on familiar routines, become distressed by unexpected changes or prefer activities to happen in a particular order.
Predictability may help the person feel safe and understand what will happen next.
3. Highly focused interests
An Autistic person may develop strong and detailed interests in particular subjects, objects or activities.
These interests can provide enjoyment, emotional regulation, connection and pathways to education or employment. They become clinically relevant when their intensity or focus forms part of the broader diagnostic picture.
4. Sensory differences
A person may be particularly sensitive or less responsive to sound, light, touch, taste, smell, temperature, pain or movement.
For example, everyday sounds may feel overwhelming, certain clothing may be uncomfortable or the person may seek movement and pressure to feel regulated.
Additional Diagnostic Requirements
The DSM 5 TR also requires that:
- The characteristics were present during the early developmental period, even if they became noticeable later
- The characteristics have a clinically significant effect on social, educational, occupational or other important areas of life
- The presentation is not better explained by intellectual disability or global developmental delay alone
Some people are identified later because they learned to mask their differences or because their environment previously placed fewer demands on them. Girls, women, adults and culturally diverse people have historically been more likely to be overlooked.
What Are the 3 Levels of Autism?
The levels describe the amount of support a person may require in two areas: social communication and restricted or repetitive patterns.
A clinician may assign different levels to these two areas. For example, a person might require substantial support with social communication but only some support with flexibility and routines.
Level 1: Requiring Support
A person at Level 1 may communicate using full sentences and manage many daily activities independently. However, they may experience difficulty initiating interaction, interpreting social information, changing between activities or organising everyday responsibilities.
Their needs may be less visible, particularly if they mask or perform well academically. This does not mean their difficulties are minor. Maintaining the appearance of coping can require significant effort and may contribute to exhaustion, anxiety or burnout.
Level 2: Requiring Substantial Support
At Level 2, differences in social communication and flexibility are generally more noticeable, even when support is available.
The person may use fewer words, communicate in an individual way or require support to participate in conversations and social activities. Changes, transitions, sensory demands or interruptions to routines may cause significant distress and interfere with daily participation.
Regular, individualised support may be required across home, education, employment and community settings.
Level 3: Requiring Very Substantial Support
A person at Level 3 experiences significant differences that affect daily functioning. They may use limited spoken language or communicate through gestures, pictures, signs or a communication device.
The person may experience intense distress when routines change and may require extensive assistance with communication, personal care, safety, emotional regulation and community participation.
A need for very substantial support does not mean a person cannot learn, form relationships, make choices or enjoy a meaningful life.
Autism Levels Are Not Fixed Labels
Support needs can change over time and across environments. A person may cope well at home but require substantial support at school, work or in unfamiliar settings. Illness, stress, sensory overload and major life changes may also affect functioning.
The diagnostic level does not describe every part of the person. It does not measure intelligence, empathy, talent or future potential. It also does not automatically determine eligibility for the NDIS, which considers functional impairment and individual circumstances.
Terms such as “high functioning” and “low functioning” can hide important needs or overlook abilities. Describing the person’s actual strengths and support requirements is usually more accurate.
The Most Important Message
The diagnostic criteria provide a structured way to identify autism, while the three levels offer a general description of support needs.
A diagnosis should lead to greater understanding, not limitation. The most useful question is not simply, “What level is this person?” It is, “What are their strengths, what barriers are they experiencing and what support will help them communicate, participate and live well?”
Sources
Autism CRC: National Guideline for the Assessment and Diagnosis of Autism in Australia
Healthdirect Australia: Autism
Centers for Disease Control and Prevention: Clinical Testing and Diagnosis for Autism
National Autistic Society: Criteria and Tools Used in an Autism Assessment
