Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by: (1) persistent impairments in reciprocal social communication and social interaction, and (2) restricted, repetitive patterns of behaviour, interests, or activities. The manifestations and functional impact of the disorder vary greatly depending on the severity of the autistic symptoms, developmental level, and chronological age. Thus, the term spectrum is used in the diagnosis.
Persistent deficits in social communication and social interaction across multiple contexts, as
manifested by all
of the following, currently or by history (examples are illustrative and not exhaustive, see DSM-5 text for more examples[6]):
Criterion A
severity is based on the severity level table below.
Restricted, repetitive patterns of behaviour, interests, or activities, as manifested by at least 2
of the following, currently or by history (examples are illustrative and not exhaustive; see text[7]):
Criterion B severity is based on the severity level table below.
Symptoms must be present in the early developmental period (but may not become fully manifest until social demands exceed limited capacities, or may be masked by learned strategies in later life).
Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.
These disturbances are not better explained by intellectual disability (intellectual developmental disorder) or global developmental delay. Intellectual disability and autism spectrum disorder frequently co-occur; to make co-morbid diagnoses of autism spectrum disorder and intellectual disability, social communication should be below that expected for general developmental level.
Severity (Level) | Social Communication (Criterion A) | Restricted, Repetitive Behaviours (Criterion B) |
---|---|---|
Requiring very substantial support (Level 3) | Severe deficits in verbal and nonverbal social communication skills cause severe impairments in functioning, very limited initiation of social interactions, and minimal response to social overtures from others. For example, a person with few words of intelligible speech who rarely initiates interaction and, when he or she does, makes unusual approaches to meet needs only and responds to only very direct social approaches. | Inflexibility of behaviour, extreme difficulty coping with change, or other restricted/repetitive behaviours, markedly interfere with functioning in all spheres. Great distress/difficulty changing focus or action. |
Requiring substantial support (Level 2) | Marked deficits in verbal and nonverbal social communication skills; social impairments apparent even with supports in place; limited initiation of social interactions; and reduced or abnormal responses to social overtures from others. For example, a person who speaks simple sentences, whose interaction is limited to narrow special interests, and who has markedly odd nonverbal communication. | Inflexibility of behaviour, difficulty coping with change, or other restricted/repetitive behaviours appear frequently enough to be obvious to the casual observer and interfere with functioning in a variety of contexts. Distress and/or difficulty changing focus or action. |
Requiring support (Level 1) | Without supports in place, deficits in social communication cause noticeable impairments. Difficulty initiating social interactions, and clear examples of atypical or unsuccessful responses to social overtures of others. May appear to have decreased interest in social interactions. For example, a person who is able to speak in full sentences and engages in communication but whose to-and-fro conversation with others fails, and whose attempts to make friends are odd and typically unsuccessful. | Inflexibility of behaviour causes significant interference with functioning in one or more contexts. Difficulty switching between activities. Problems of organization and planning hamper independence. |
If there is an accompanying intellectual impairment, indicate this in the diagnosis. Understanding the intellectual profile of a child or adult with autism spectrum disorder is important for interpreting diagnostic features. Separate estimates of verbal and nonverbal skill are necessary (e.g. - using untimed nonverbal tests to assess potential strengths in individuals with limited language).
If there is accompanying language impairment, the current level of verbal functioning should be recorded (e.g. - “with accompanying language impairment—no intelligible speech” or “with accompanying language impairment—phrase speech”).
Record “autism spectrum disorder associated with (name of condition or factor).” This can be a known genetic disorder (e.g. - Rett syndrome, Fragile X syndrome, Down syndrome), a medical disorder (e.g. - epilepsy), or a history of environmental exposure (e.g. - valproic acid, fetal alcohol syndrome, low birth weight).
Record autism spectrum disorder associated with (name of disorder) (e.g. - autism spectrum disorder associated with tic disorder).
If catatonia is present, record separately as “catatonia associated with autism spectrum disorder.”
Symptoms of autism are typically recognized during the second year of life (12-24 months of age), and can be reliably diagnosed by age 14 months.[8]
Standardized behavioural diagnostic instruments with good psychometric properties, including caregiver interviews, questionnaires and clinician observation measures can improve the reliability of diagnosis.
Less than 1 percent of non-syndromic cases of autism are due to mutations in a single gene. The environment (ranging from chemical changes in gene expression, to the absorption of nutrients in the womb) is also thought to play a factor.[11]