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What is Autism Spectrum Disorder?

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects how people interact with others, communicate, learn, and behave (National Institute of Mental Health, 2022). As the name suggests, ASD is a spectrum and clinical presentations vary from one person to another. As the medical and psychological communities learn more about ASD, the diagnostic criteria have been updated to help improve identifying and diagnosing ASD. ASD can be diagnosed at any age and in many patients, it’s diagnosed in the first few years of life as symptoms generally appear in the first two years of life. However, many individuals are now being diagnosed in adulthood, especially women, whose symptoms may have been overlooked or previously misdiagnosed in the past.

ASD is diagnosed using the DSM-5 criteria set forth by the American Psychiatric Association’s Diagnostic and Statistical Manual. Meeting the criteria for an ASD diagnosis requires persistent deficits in the following three areas of social communication and interaction (section A), and additionally, at least two of four types of restricted, repetitive behaviors (section B):

Section A

  • Persistent deficits in social communication and social interaction across multiple contexts, as manifested by the following, currently or by history (examples are illustrative, not exhaustive; see text):

    • Deficits in social-emotional reciprocity, range, for example, from abnormal social approach and failure of normal back-and-forth conversation; to reduced sharing of interests, emotions, or affect; to failure to initiate or respond to social interactions.

    • Deficits in nonverbal communicative behaviors used for social interaction, ranging, for example, from poorly integrated verbal and nonverbal communication; to abnormalities in eye contact and body language or deficits in understanding and use of gestures; to a total lack of facial expressions and nonverbal communication.

    • Deficits in developing, maintaining, and understanding relationships, ranging, for example, from difficulties adjusting behavior to suit various social contexts; to difficulties in sharing imaginative play or in making friends; to absence of interest in peers.

Section B

  • Restricted, repetitive patterns of behavior, interests, or activities, as manifested by at least two of the following, currently or by history (examples are illustrative, not exhaustive; see text):

    • Stereotyped or repetitive motor movements, use of objects, or speech (e.g., simple motor stereotypes, lining up toys or flipping objects, echolalia, idiosyncratic phrases).

    • Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior (e.g., extreme distress at small changes, difficulties with transitions, rigid thinking patterns, greeting rituals, need to take the same route or eat the same food every day).

    • Highly restricted, fixated interests that are abnormal in intensity or focus (e.g., strong attachment to or preoccupation with unusual objects, excessively circumscribed or perseverative interests).

    • Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment (e.g. apparent indifference to pain/temperature, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement).

Specification of Severity

Severity is based on social communication impairments and restricted, repetitive patterns of behavior.

  1. 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).

  2. Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.

  3. 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 comorbid diagnoses of autism spectrum disorder and intellectual disability, social communication should be below that expected for general developmental level.

Additional Specifications

  • With or without accompanying intellectual impairment, with or without accompanying language impairment

  • Associated with a known medical or genetic condition or environmental factor

  • Associated with another neurodevelopmental, mental, or behavioral disorder

  • With catatonia (refer to the criteria for catatonia associated with another mental disorder)

Note on Asperger’s Syndrome

Asperger’s syndrome is technically not a diagnosis anymore. However, individuals who were previously diagnosed with Asperger’s syndrome are now assigned the diagnosis of ASD.

Resources for Adult Screening of ASD:


American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013.

Autism Spectrum Disorder. National Institute of Mental Health (NIMH). (2022). Retrieved 23 March 2022, from

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