DSM, Fifth edition criteria – According to the DSM, Fifth edition Text Revision (DSM-5-TR) criteria, a diagnosis of ASD requires all of the following [
30]:
•Persistent deficits in social communication and social interaction in multiple settings; demonstrated by deficits in all three of the following (either currently or by history):
-Social-emotional reciprocity (eg, failure to produce mutually enjoyable and agreeable conversations or interactions because of a lack of mutual sharing of interests, lack of awareness or understanding of the thoughts or feelings of others)
-Nonverbal communicative behaviors used for social interaction (eg, difficulty coordinating verbal communication with its nonverbal aspects [eye contact, facial expressions, gestures, body language, and/or prosody/tone of voice])
-Developing, maintaining, and understanding relationships (eg, difficulty adjusting behavior to social setting, lack of ability to show expected social behaviors, lack of interest in socializing, difficulty making friends even when interested in having friendships)
•Restricted, repetitive patterns of behavior, interests, or activities; demonstrated by ≥2 of the following (either currently or by history):
-Stereotyped or repetitive movements, use of objects, or speech (eg, stereotypies such as rocking, flapping, or spinning; echolalia [repeating parts of speech]; repeating scripts from movies or prior conversations; ordering toys into a line)
-Insistence on sameness, unwavering adherence to routines, or ritualized patterns of verbal or nonverbal behavior (eg, difficulty with transitions, greeting rituals, need to eat the same food every day)
-Highly restricted, fixated interests that are abnormal in strength or focus (eg, preoccupation with certain objects [trains, vacuum cleaners, or parts of trains or vacuum cleaners]); perseverative interests (eg, excessive focus on a topic such as dinosaurs or natural disasters)
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-Increased or decreased response to sensory input or unusual interest in sensory aspects of the environment (eg, adverse response to particular sounds; apparent indifference to temperature; excessive touching/smelling of objects)
•The symptoms must impair function (eg, social, academic, completing daily routines).
•The symptoms must be present in the early developmental period. However, they may become apparent only after social demands exceed limited capacity; in later life, symptoms may be masked by learned strategies.
•The symptoms are not better explained by intellectual disability or global developmental delay.
ASD may occur with or without medical, genetic, neurodevelopmental, mental, or behavioral problems (eg, intellectual impairment, language impairment, epilepsy, fetal
valproate or alcohol exposure). The presence or absence of these problems are specified as part of the DSM-5-TR diagnosis of ASD (eg, ASD with accompanying intellectual impairment, ASD without accompanying language impairment) [
30]. Some accompanying conditions are identified during the comprehensive evaluation; others may require additional testing. (See
'Evaluation for associated conditions' below.)
The clinical features of ASD, including examples of deficits and abnormal functioning in these domains, are discussed separately. (See
"Autism spectrum disorder in children and adolescents: Clinical features".)
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ICD 11th Revision criteria – The ICD 11th Revision (ICD-11) criteria for the diagnosis of ASD are provided in
ICD-11 for Mortality and Morbidity Statistics [
31].
Assessment of severity — In conjunction with an adaptive scale (eg, Vineland Adaptive Behavior Scale, Adaptive Behavior Assessment System), we use the DSM-5-TR classification to specify the severity level of ASD, recognizing that severity may vary with context and over time [
30]. Severity should be assessed separately for each domain, as indicated below. Co-occurring intellectual impairment often accounts for the differences in levels of severity.