Caution: The following text is extracted from the ICD-11 definition of Autism Spectrum Disorder (ASD). It is provided for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Please note that this summary may not reflect the most up-to-date version of the ICD-11. The official and current listing can be found on the World Health Organization’s website: ICD-11: Autism Spectrum Disorder.

Autism Spectrum Disorder

Foundation URI: http://id.who.int/icd/entity/437815624

Code: 6A02

Description

Autism spectrum disorder is characterised by persistent deficits in the ability to initiate and to sustain reciprocal social interaction and social communication, and by a range of restricted, repetitive, and inflexible patterns of behaviour, interests or activities that are clearly atypical or excessive for the individual’s age and sociocultural context. The onset of the disorder occurs during the developmental period, typically in early childhood, but symptoms may not become fully manifest until later, when social demands exceed limited capacities. Deficits are sufficiently severe to cause impairment in personal, family, social, educational, occupational or other important areas of functioning and are usually a pervasive feature of the individual’s functioning observable in all settings, although they may vary according to social, educational, or other context. Individuals along the spectrum exhibit a full range of intellectual functioning and language abilities.

Diagnostic Requirements

Essential (Required) Features:

• Persistent deficits in initiating and sustaining social communication and reciprocal social interactions that are outside the expected range of typical functioning given the individual’s age and level of intellectual development. Specific manifestations of these deficits vary according to chronological age, verbal and intellectual ability, and disorder severity. Manifestations may include limitations in the following:
• Understanding of, interest in, or inappropriate responses to the verbal or non-verbal social communications of others.
• Integration of spoken language with typical complimentary non-verbal cues, such as eye contact, gestures, facial expressions and body language. These non-verbal behaviours may also be reduced in frequency or intensity.
• Understanding and use of language in social contexts and ability to initiate and sustain reciprocal social conversations.
• Social awareness, leading to behaviour that is not appropriately modulated according to the social context.
• Ability to imagine and respond to the feelings, emotional states, and attitudes of others.
• Mutual sharing of interests.
• Ability to make and sustain typical peer relationships.
• Persistent restricted, repetitive, and inflexible patterns of behaviour, interests, or activities that are clearly atypical or excessive for the individual’s age and sociocultural context. These may include:
• Lack of adaptability to new experiences and circumstances, with associated distress, that can be evoked by trivial changes to a familiar environment or in response to unanticipated events.
• Inflexible adherence to particular routines; for example, these may be geographic such as following familiar routes, or may require precise timing such as mealtimes or transport.
• Excessive adherence to rules (e.g., when playing games).
• Excessive and persistent ritualized patterns of behaviour (e.g., preoccupation with lining up or sorting objects in a particular way) that serve no apparent external purpose.
• Repetitive and stereotyped motor movements, such as whole body movements (e.g., rocking), atypical gait (e.g., walking on tiptoes), unusual hand or finger movements and posturing. These behaviours are particularly common during early childhood.
• Persistent preoccupation with one or more special interests, parts of objects, or specific types of stimuli (including media) or an unusually strong attachment to particular objects (excluding typical comforters).
• Lifelong excessive and persistent hypersensitivity or hyposensitivity to sensory stimuli or unusual interest in a sensory stimulus, which may include actual or anticipated sounds, light, textures (especially clothing and food), odors and tastes, heat, cold, or pain.
• The onset of the disorder occurs during the developmental period, typically in early childhood, but characteristic symptoms may not become fully manifest until later, when social demands exceed limited capacities.
• The symptoms result in significant impairment in personal, family, social, educational, occupational or other important areas of functioning. Some individuals with Autism Spectrum Disorder are able to function adequately in many contexts through exceptional effort, such that their deficits may not be apparent to others. A diagnosis of Autism Spectrum Disorder is still appropriate in such cases.

Specifiers for characterizing features within the Autism Spectrum:

These specifiers enable the identification of co-occurring limitations in intellectual and functional language abilities, which are important factors in the appropriate individualization of support, selection of interventions, and treatment planning for individuals with Autism Spectrum Disorder. A qualifier is also provided for loss of previously acquired skills, which is a feature of the developmental history of a small proportion of individuals with Autism Spectrum Disorder.

Co-occurring Disorder of Intellectual Development

Individuals with Autism Spectrum Disorder may exhibit limitations in intellectual abilities. If present, a separate diagnosis of Disorder of Intellectual Development should be assigned, using the appropriate category to designate severity (i.e., Mild, Moderate, Severe, Profound, Provisional). Because social deficits are a core feature of Autism Spectrum Disorder, the assessment of adaptive behaviour as a part of the diagnosis of a co-occurring Disorder of Intellectual Development should place greater emphasis on the intellectual, conceptual, and practical domains of adaptive functioning than on social skills.

If no co-occurring diagnosis of Disorder of Intellectual Development is present, the following qualifier for the Autism Spectrum Disorder diagnosis should be applied:

• without Disorder of Intellectual Development

If there is a co-occurring diagnosis of Disorder of Intellectual Development, the following qualifier for the Autism Spectrum Disorder diagnosis should be applied, in addition to the appropriate diagnostic code for the co-occurring Disorder of Intellectual Development:

• with Disorder of Intellectual Development

Degree of Functional Language Impairment

The degree of impairment in functional language (spoken or signed) should be designated with a second qualifier. Functional language refers to the capacity of the individual to use language for instrumental purposes (e.g., to express personal needs and desires). This qualifier is intended to reflect primarily the verbal and non-verbal expressive language deficits present in some individuals with Autism Spectrum Disorder and not the pragmatic language deficits that are a core feature of Autism Spectrum Disorder.

The following qualifier should be applied to indicate the extent of functional language impairment (spoken or signed) relative to the individual’s age:

• with mild or no impairment of functional language
• with impaired functional language (i.e., not able to use more than single words or simple phrases)
• with complete, or almost complete, absence of functional language

Table 6.5 Diagnostic Codes for Autism Spectrum Disorder

Table 6.5 shows the diagnostic codes corresponding to the categories that result from the application of the specifiers for Co-occurring Disorder of Intellectual Development and Degree of Functional Language Impairment.

Note: The ICD-11 and DSM-5 classify Autism Spectrum Disorder differently. The ICD-11 uses diagnostic codes with specifiers, while the DSM-5 emphasises support levels.

In the DSM-5, criteria span two domains:

• Social Communication: Persistent deficits in social communication and interaction
• RRBs: Restricted, repetitive patterns of behaviour, interests, or activities

Each domain is rated according to support needs:

• Level 1: Requiring support
• Level 2: Requiring substantial support
• Level 3: Requiring very substantial support

Loss of Previously Acquired Skills

A small proportion of individuals with Autism Spectrum Disorder may present with a loss of previously acquired skills. This regression typically occurs during the second year of life and most often involves language use and social responsiveness. Loss of previously acquired skills is rarely observed after 3 years of age. If it occurs after age 3, it is more likely to involve loss of cognitive and adaptive skills (e.g., loss of bowel and bladder control, impaired sleep), regression of language and social abilities, as well as increasing emotional and behavioural disturbances.

There are two alternative specifiers, to denote whether or not loss of previously acquired skills is an aspect of the clinical history, where x corresponds to the final digit shown in Table 6.5:

Additional Clinical Features:

• Common symptom presentations of Autism Spectrum Disorder in young children are parental or caregiver concerns about intellectual or other developmental delays (e.g., problems in language and motor coordination). When there is no significant impairment of intellectual functioning, clinical services may only be sought later (e.g., due to behaviour or social problems when starting school). In middle childhood, there may be prominent symptoms of anxiety, including Social Anxiety Disorder, school refusal, and Specific Phobia. During adolescence and adulthood, Depressive Disorders are often a presenting feature.
• Co-occurrence of Autism Spectrum Disorder with other Mental, Behavioural or Neurodevelopmental Disorders is common across the lifespan. In a substantial proportion of cases, particularly in adolescence and adulthood, it is a co-occurring disorder that first brings an individual with Autism Spectrum Disorder to clinical attention.
• Pragmatic language difficulties may manifest as an overly literal understanding of others’ speech, speech that lacks normal prosody and emotional tone and therefore appears monotonous, lack of awareness of the appropriateness of their choice of language in particular social contexts, or pedantic precision in the use of language.
• Social naiveté, especially during adolescence, can lead to exploitation by others, a risk that may be enhanced by the use of social media without adequate supervision.
• Profiles of specific cognitive skills in Autism Spectrum Disorder as measured by standardized assessments may show striking and unusual patterns of strengths and weaknesses that are highly variable from individual to individual. These deficits can affect learning and adaptive functioning to a greater extent than would be predicted from the overall scores on measures of verbal and non-verbal intelligence.
• Self-injurious behaviours (e.g., hitting one’s face, head banging) occur more often in individuals with co-occurring Disorder of Intellectual Development.
• Some young individuals with Autism Spectrum Disorder, especially those with a co-occurring Disorder of Intellectual Development, develop epilepsy or seizures during early childhood with a second increase in prevalence during adolescence. Catatonic states have also been described. A number of medical disorders such as Tuberous Sclerosis, chromosomal abnormalities including Fragile X Syndrome, Cerebral Palsy, early onset epileptic encephalopathies, and Neurofibromatosis are associated with Autism Spectrum Disorder with or without a co-occurring Disorder of Intellectual Development. Genomic deletions, duplications and other genetic abnormalities are increasingly described in individuals with Autism Spectrum Disorder, some of which may be important for genetic counselling. Prenatal exposure to valproate is also associated with an increased risk of Autism Spectrum Disorder.
• Some individuals with Autism Spectrum Disorder are capable of functioning adequately by making an exceptional effort to compensate for their symptoms during childhood, adolescence or adulthood. Such sustained effort, which may be more typical of affected females, can have a deleterious impact on mental health and well-being.

Boundary with Normality (Threshold):

• Social interaction skills: Typically developing individuals vary in the pace and extent to which they acquire and master skills of reciprocal social interaction and social communication. A diagnosis of Autism Spectrum Disorder should only be considered if there is marked and persistent deviation from the expected range of abilities and behaviours in these domains given the individual’s age, level of intellectual functioning, and sociocultural context. Some individuals may exhibit limited social interaction due to shyness (i.e., feelings of awkwardness or fear in new situations or with unfamiliar people) or behavioural inhibition (i.e., being slow to approach or to ‘warm up’ to new people and situations). Limited social interactions in shy or behaviourally inhibited children, adolescents, or adults are not indicative of Autism Spectrum Disorder. Shyness is differentiated from Autism Spectrum Disorder by evidence of adequate social communication behaviours in familiar situations.
• Social communication skills: Children vary widely in the age at which they first acquire spoken language and the pace at which their speech and language become firmly established. Most children with early language delay eventually acquire similar language skills as their same-age peers. Early language delay alone is not strongly indicative of Autism Spectrum Disorder unless there is also evidence of limited motivation for social communication and limited interaction skills. An essential feature of Autism Spectrum Disorder is persistent impairment in the ability to understand and use language appropriately for social communication.
• Repetitive and stereotyped behaviours: Many children go through phases of repetitive play and highly focused interests as a part of typical development. Unless there is also evidence of impaired reciprocal social interaction and social communication, patterns of behaviour characterized by repetition, routine, or restricted interests are not by themselves indicative of Autism Spectrum Disorder.

Course Features:

• Although Autism Spectrum Disorder can present clinically at all ages, including during adulthood, it is a lifelong disorder the manifestations and impact of which are likely to vary according to age, intellectual and language abilities, co-occurring conditions and environmental context.
• Restricted and repetitive behaviours persist over time. Specifically, repetitive sensorimotor behaviours appear to be common, consistent, and potentially severe. During the school age years and adolescence, these repetitive sensorimotor behaviours begin to lessen in intensity and number. Insistence on sameness, which is less prevalent, appears to develop during preschool and worsen over time.

Developmental Presentations:

• Infancy: Characteristic features may emerge during infancy although they may only be recognized as indicative of Autism Spectrum Disorder in retrospect. It is usually possible to make the diagnosis of Autism Spectrum Disorder during the preschool period (up to 4 years), especially in children exhibiting generalized developmental delay. Plateauing of social communication and language skills and failure to progress in their development is not uncommon. The loss of early words and social responsiveness, i.e., a true regression, with an onset between 1 and 2 years, is unusual but significant and rarely occurs after the third year of life. In these cases, the qualifier ‘with loss of previously acquired skills’ should be applied.
• Preschool: In preschool children, indicators of an Autism Spectrum Disorder diagnosis often include avoidance of mutual eye contact, resistance to physical affection, a lack of social imaginary play, language that is delayed in onset or is precocious but not used for social conversation; social withdrawal, obsessive or repetitive preoccupations, and a lack of social interaction with peers characterized by parallel play or disinterest. Sensory sensitivities to everyday sounds, or to foods, may overshadow the underlying social communication deficits.
• Middle Childhood: In children with Autism Spectrum Disorder without a Disorder of Intellectual Development, social adjustment difficulties outside the home may not be detected until school entry or adolescence when social communication problems lead to social isolation from peers. Resistance to engage in unfamiliar experiences and marked reactions to even minor change in routines are typical. Furthermore, excessive focus on detail as well as rigidity of behaviour and thinking may be significant. Symptoms of anxiety may become evident at this stage of development.
• Adolescence: By adolescence, the capacity to cope with increasing social complexity in peer relationships at a time of increasingly demanding academic expectations is often overwhelmed. In some individuals with Autism Spectrum Disorder, the underlying social communication deficits may be overshadowed by the symptoms of co-occurring Mental and Behavioural Disorders. Depressive symptoms are often a presenting feature
• Adulthood: In adulthood, the capacity for those with Autism Spectrum Disorder to cope with social relationships can become increasingly challenged, and clinical presentation may occur when social demands overwhelm the capacity to compensate. Presenting problems in adulthood may represent reactions to social isolation or the social consequences of inappropriate behaviour. Compensation strategies may be sufficient to sustain dyadic relationships, but are usually inadequate in social groups. Special interests, and focused attention, may benefit some individuals in education and employment. Work environments may have to be tailored to the capacities of the individual. A first diagnosis in adulthood may be precipitated by a breakdown in domestic or work relationships. In Autism Spectrum Disorder there is always a history of early childhood social communication and relationship difficulties, although this may only be apparent in retrospect.

Culture-Related Features:

• Cultural variation exists in norms of social communication, reciprocal social interactions, as well as interests and activities. Therefore, signs of impairment in functioning may differ depending on cultural context. For example, in some societies it may be normative for children may avoid direct eye contact out of deference, which should not be misinterpreted as impairment in social interaction.

Sex- and/or Gender-Related Features:

• Males are four times more likely than females to be diagnosed with Autism Spectrum Disorder.
• Females diagnosed with Autism Spectrum Disorder are more frequently diagnosed with co-occurring Disorders of Intellectual Development, suggesting that less severe presentations may go undetected as compared to males. Females tend to demonstrate fewer restricted, repetitive interests and behaviours than males.
• During middle-childhood, gender differences in presentation differentially affect functioning. Boys may act out with reactive aggression or other behavioural symptoms when challenged or frustrated. Girls tend to withdraw socially, and react with emotional changes to their social adjustment difficulties.