Autism spectrum in ICD-11 - what has changed

The autism spectrum as a single category

Autism spectrum disorder is a pervasive neurodevelopmental disorder (that is, one linked to brain development from the earliest years) that affects social communication as well as patterns of behaviour and interests. In the ICD-11 classification (the eleventh revision of the International Classification of Diseases prepared by the World Health Organization) it is listed under the code 6A02.

The most important change from the previous version is the merging of several formerly separate diagnoses into a single category. Earlier, the ICD-10 classification distinguished, among others, childhood autism, atypical autism, Asperger syndrome and other pervasive developmental disorders as separate entities. ICD-11 treats these clinical pictures as variants of a single spectrum.

The notion of a spectrum reflects the fact that autism presents in very different ways. It encompasses people who are fully independent and use rich language, as well as people who require constant support and have limited speech. Instead of artificially dividing this continuum into separate diagnoses, the ICD-11 classification describes it through a single category supplemented with additional qualifiers.

Why Asperger syndrome disappeared

One of the most widely discussed changes is that Asperger syndrome is no longer a separate diagnostic entity. This does not mean that people who received such a diagnosis have stopped being autistic - they are now included within the general category of autism spectrum disorder.

The reason for abandoning the separate category was practical difficulty. Research showed that the boundary between Asperger syndrome and so-called high-functioning autism was indistinct, and that different clinicians gave different diagnoses for a similar clinical picture. The distinction also did not translate into clearly different therapeutic needs.

In ICD-11, the clinical picture formerly described as Asperger syndrome usually corresponds to autism spectrum disorder without disorder of intellectual development and with intact or only mildly impaired functional language. The information that was previously contained in the name is now conveyed more precisely through qualifiers.

Two main domains of criteria

ICD-11 describes autism spectrum disorder through two main domains of difficulty. The first is deficits in social communication and social interaction, present across a wide range of situations. The second is restricted, repetitive and inflexible patterns of behaviour, interests or activities.

In the domain of social communication, the difficulties may include limited understanding of social cues, difficulty reading other people's intentions and emotions, atypical eye contact, and a reduced ability to hold a conversation and build age-appropriate relationships. This is not an absence of the wish for contact, but a different way of processing social information.

In the domain of behaviour patterns, there may be repetitive movements or activities, a strong need for sameness and predictability, marked discomfort with changes to routine, intense and narrow interests, and atypical responses to sensory input such as sounds, light, touch or textures. A diagnosis requires features from both domains.

Onset in the developmental period

The third condition for a diagnosis is the onset of difficulties in the developmental period. Autism features are usually present in early childhood, although their full intensity may only become apparent later, when social demands exceed the individual person's capacities.

ICD-11 takes into account an important clinical observation: in some people, especially those with good cognitive abilities, the difficulties may be masked or compensated for over many years. Learned coping strategies allow them to function in simpler conditions, and clear problems appear only in situations with greater social demands.

For this reason the classification also permits a diagnosis of autism in adolescents and adults, if the developmental history points to the presence of features since childhood. This is a significant practical change that makes diagnosis easier for people who have gone many years without a diagnosis, including women, in whom autism is sometimes recognised later.

Qualifiers - intellectual abilities and language

Since autism is now a single category, a way was needed to describe the enormous diversity within the spectrum. ICD-11 addresses this through qualifiers, that is, additional designations that refine the 6A02 diagnosis.

The first qualifier concerns the co-occurrence of disorder of intellectual development - the diagnosis indicates whether or not the autism is accompanied by reduced intellectual abilities. The second qualifier describes the degree of impairment of functional language, that is, the ability to use speech for everyday communication: from no significant difficulty, through mild impairment, to an absence of functional language.

Combining these qualifiers gives a far richer picture than the former names did. It makes it possible to distinguish, among others, an autistic person without disorder of intellectual development and with intact language from a person who requires constant support, has limited speech and a co-occurring disorder of intellectual development, which in ICD-11 has its own code 6A00.

Autism and the level of support

Although ICD-11 does not use a formal scale of support levels, the description of the category itself and its qualifiers make it possible to capture how much help a given person needs in everyday life. The clinician describes the real impact of the difficulties on functioning across different domains.

For some people, support consists mainly of adjusting the environment, for example a predictable routine, reducing excess stimulation or clear communication. Others need constant, intensive help with communication, independence and safety. The same diagnostic criteria cover both of these situations.

This approach emphasises that a diagnosis of autism does not in itself tell us what a given person's life will look like. It describes a way of processing social information and organising behaviour, whereas the need for support depends on the individual profile, the environment and co-occurring difficulties.

Co-occurring disorders

Autism very often co-occurs with other disorders, and ICD-11 makes it easier to diagnose them alongside one another. This applies above all to anxiety disorders, mood disorders and attention deficit hyperactivity disorder (code 6A05), which in the ICD-11 classification may be diagnosed together with autism.

In autistic people, more often than in the general population, there are also difficulties with sleep, feeding disorders linked among other things to food selectivity, and disorders of intellectual development. Co-occurring problems can strongly affect well-being and functioning, sometimes more than the autistic features themselves.

Recognising co-occurring conditions is of great practical importance. It makes it possible to provide the patient with broader support and to avoid reducing every difficulty to a single label. In ICD-11 diagnosis it is important to ask not only whether autism is present, but also what else needs attention and help.

Differential diagnosis from other disorders

Some features of autism may resemble other disorders, which is why careful differential diagnosis is an important part of the diagnostic process. Difficulties in social communication must be distinguished from developmental speech and language disorders, in which the core problem is language itself rather than a broader pattern of social functioning.

Repetitive behaviours and rigid routines may resemble obsessive-compulsive disorder. The difference is that in autism the repetitiveness is often a source of regulation and a sense of safety, whereas in obsessive-compulsive disorder the activities are usually experienced as a distressing compulsion. Rigid patterns of behaviour are also sometimes confused with features of personality disorder (code 6D10), which, however, has a different course and basis.

Social withdrawal and limited expression of emotion, in turn, need to be distinguished from schizophrenia spectrum disorders and from the effects of neglect during the developmental period. The key lies in the overall clinical picture and its course from early childhood. Careful differential diagnosis guards against both missing autism and over-diagnosing it.

What the change means in practice

For autistic people and their families, merging the former categories into a single spectrum has several practical consequences. The diagnosis is more consistent across clinicians, and a change in the clinical picture over time does not require a change of the diagnostic entity itself - it is enough to update the qualifiers.

For clinicians, the new model means they must describe the patient's profile precisely instead of choosing one of several similar labels. This calls for a thorough developmental history, observation and consideration of functioning across different situations. ICD-11 diagnosis therefore emphasises individual description rather than fitting the person to a ready-made category.

The change also has a social dimension. The disappearance of the name Asperger syndrome is difficult for some people, because it had been part of their identity. At the same time, a single shared concept of the autism spectrum makes communication, the organisation of support and scientific research into the varied presentations of autism easier.

Summary

ICD-11 brings order to the diagnosis of autism by merging the former separate diagnoses into a single category, autism spectrum disorder, with the code 6A02. The diagnosis rests on three elements: deficits in social communication, restricted and repetitive patterns of behaviour, and onset in the developmental period.

The diversity of autistic people is captured by qualifiers concerning intellectual abilities and functional language, and the attention given to co-occurring disorders and to differential diagnosis makes the assessment more complete. The new model better reflects clinical knowledge and makes it easier to provide support to people of every age. This material is for informational purposes and does not replace a consultation with a specialist.

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