Autism spectrum disorder

Background

Epidemiology

• About 1% of the population in developed countries

Diagnosis

DSM-5 Criteria

• A. Persistent deficits in social communication and social interaction across multiple contexts, as manifested by the following:
  • Deficits in social-emotional reciprocity, ranging, for example, from abnormal social approach and failure of normal back-and-forth conservation; to reduced sharing of interests, emotions, or affect; to fialure to initiate or respond to social interactions.
  • Deficits in nonverbal communicative behaviours 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 behaviour to suit various social contexts; to difficulties in sharing imaginative play or in making friends; to absence of interest in peers.
  • (Specify current severity.)
• B. Restricted, repetitive patterns of behaviour, interests, or activities, as manifested by at least two of the following:
  • Stereotyped or repetitive motor movements, use of objects, or speech (e.g. simple motor stereotypies, lining up toys or flipping objects, echolalia, idiosyncratic phrases).
  • Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behaviour (e.g. extreme distress at small changes, difficulties with transitions, rigid thinking patterns, greeting rituals, need to take same route or eat 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)
  • (Specific current severity.)
• C. 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).
• D. Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.
• E. 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.
• Specify if:
  • 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 behavioural disorder
  • With catatonia
• Severity levels:
  • Level 1 (requiring support)
  • Level 2 (requiring substantial support)
  • Level 3 (requiring very substantial support)

Differential Diagnosis

• Rett syndrome
• Selective mutism
• Language disorders and social communication disorder
• Intellectual disability without autism spectrum disorder
• Stereotypic movement disorder
• Attention-deficit/hyperactivity disorder
• Schizophrenia