Note: Members of the autism spectrum disorder (ASD) community have different preferences on the use of person-first (“person with ASD”) and identity-first (“autistic person”) language. For this article, we have used a mix of person-first and identity-first language.
What are the diagnostic criteria for ASD?
There is no single blood test or X-ray that is used to diagnose autism spectrum disorder (ASD). The diagnosis of ASD relies on standard criteria included in a manual called the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition Text Revision (DSM-5-TR).
The DSM-5-TR criteria were developed to provide standards for health-care professionals to diagnose a range of disorders and conditions.
DSM-5-TR diagnostic criteria for ASD
| Domains | Subcriteria |
|---|---|
|
1. Impairment in social interaction and communication (all three subcriteria required) |
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2. Abnormal and restricted, repetitive behaviours, interests, and activities (two of four subcriteria required) |
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| 3. Signs or symptoms must be present during early development, but they may not be fully evident until later, when social demands exceed limited capacities, or they may be masked by learned strategies. | |
| 4. Symptoms interfere with everyday functioning. | |
| 5. Symptoms are not better explained by intellectual disability or global developmental delay. | |
| 6. ASD may occur with or without medical, genetic, neurodevelopmental, mental or behavioural disorders, or an intellectual or language impairment. | |
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7. Level of severity for each of the two domains may be used to refine diagnosis:
These levels may be difficult to determine at the initial time of diagnosis with very young children. |
Examples of signs and symptoms of ASD
In a toddlers and younger children, sometimes signs of ASD can be more subtle, and it is only as children grow that it becomes clearer that a child has social difficulties and behaviour differences. Below are examples of signs and symptoms of ASD for younger and older children. They are organized by the two main diagnostic domains for ASD: 1) Social communication differences and 2) Repetitive behaviours, focused interests and need for sameness.
Toddlers or young children
Social communication differences:
- Delayed language milestones
- Spoken words may be mimicked, repetitive and out of context
- Losing words previously spoken
- Limited use of gestures (e.g., waving, clapping, pointing, nodding)
- Using another person’s hand as a tool (e.g., placing a parent’s hand on an object)
- Reduced eye contact
- Reduced response to name
- Sharing less enjoyment or facial expressions with others
Repetitive behaviours, focused interests and need for sameness:
- Repetitive spoken words or phrases (e.g., copied from TV shows, movies)
- Repetitive movements (e.g., hand flapping, body rocking)
- Repetitive play with toys (e.g., lining things up, playing with the same objects)
- Sensory differences (e.g., examining objects at unique angles, being particularly sensitive to noise, difficulties with eating certain foods, preference for wearing only certain clothing, high pain tolerance)
- Distress if route to daycare/preschool is changed
- Wearing the same clothes every day (or only one colour)
- Eating the same foods every day
Older children and teenagers (in addition to the above signs)
Social communication differences:
- Different tone and pitch to their voice (e.g., less variation in speech than expected, mimicking others)
- Difficulty with back-and-forth conversations
- Difficulty understanding social cues, including facial expressions
- Facial expressions that may not match how they feel
- Challenges with maintaining peer relationships
- May not change behaviour based on environment and social expectations
- Difficulty engaging in imaginative play with peers
Repetitive behaviours, focused interests and need for sameness:
- Speaks about the same topic repeatedly
- Very strong and specific interests that may not be common amongst peers
- Shows a need to follow specific routines every day
- Have strong preferences to keep things the same way
- Difficulty with changes and transitions
How is a diagnosis of ASD made?
Diagnosing ASD requires a thorough assessment of a child, including a detailed history of their development and behaviour, direct observation and physical examination. The assessment may take place over several visits. There are several screening tools that are used to gather information and identify children who require more in-depth assessment. Along with the DSM-5-TR criteria, there are several diagnostic tools that are used by health-care providers to diagnose ASD.
Who can make a diagnose of ASD?
A health-care provider familiar with using the diagnostic tools for ASD, such as a pediatrician, psychologist or a psychiatrist, can make a diagnosis of ASD. They may work with other allied health providers, such as social workers, speech-language pathologists and occupational therapists. In some regions across Canada, there are centralized hubs for diagnostic assessment of children. Speak to your child’s health-care provider to get a referral for an autism diagnostic assessment.
For more information about ASD, visit the Autism Spectrum Disorder Learning Hub.