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Understanding autism
Understanding autism

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2.2 DSM-5, ICD-10 and ICD-11

Diagnosis, whether of a physical or psychological condition, involves comparing an individual’s symptoms with diagnostic criteria which specify which symptoms must be present for a specific diagnosis to be appropriate, together with any criteria that rule out this particular diagnosis.

There are two main official sources for autism diagnosis, the Diagnostic and Statistical Manual of Mental Disorders (DSM) (published by the American Psychiatric Association), and the International Classification of Diseases (ICD) (published by the World Health Organisation). DSM is favoured in the USA while ICD is widely used in Europe, although the DSM criteria are also influential in Europe. Both systems are also used in many other parts of the world. However, the appropriateness of western-oriented criteria for diagnosis in different cultures is questionable, as will be discussed later on.

As you learned in Weeks 1 and 2, autism involves ‘social’ and ‘non-social’ characteristics. How these are used as the basis for diagnosis depends on which diagnostic system is used. ICD-10 (the tenth version of the ICD) was introduced in 1992 (WHO, 1992) and reflects thinking about the autism spectrum at that time, including some ideas that may be familiar, such as considering Asperger syndrome a separable sub-type of autism. DSM-5 (the fifth version of the manual) was introduced in 2013 and reflects more recent thinking, including the removal of Asperger syndrome as a separable sub-type. It is important to understand the evolution from ICD-10 to DSM-5. At the time of finalising this module, both remain in operation. The details of ICD-11 were released in June 2018. After presentation to WHO member states in 2019, it will come into use in 2022. It will mirror DSM-5 in most key respects but includes some different features which are being viewed as improvements (Zeldovich, 2017). Table 1 summarises the key differences between ICD-10 and DSM-5, with some additional notes on ICD-11. For all autism diagnoses, an overarching criterion is whether the observed symptoms are sufficient to undermine the individual’s functioning in everyday life. A clinician may decide, for instance, that a person’s mild problems of social communication, and slightly repetitive behaviours and interests are not sufficiently disruptive to merit diagnosis.

Differences between ICD-10 and DSM-5, with explanatory notes
What are the possible diagnoses?

Three different autism subtypes:

Childhood autism; Asperger syndrome; Pervasive developmental disorder – unspecified (information insufficient to diagnose autism or Asperger syndrome).

A single diagnosis:

Autism spectrum disorder.

In ICD-10, the ‘spectrum’ is divided into three subtypes. DSM-5 has relinquished subtypes such as Asperger in favour of a single continuous spectrum, reflecting the variability of symptoms and how they are expressed. ICD-11 mirrors this DSM-5 approach, but does differentiate autism with and without intellectual disability.
What are the main types of symptom?


Problems in:

1) communication

2) social interaction

3) restrictive, repetitive activities and interests (RRBIs).


Problems in:

1) social communication

2) restrictive, repetitive activities and interests; sensory difficulties.

DSM-5 and ICD-11 both merge communication and social interaction into one social communication symptom cluster. Clinicians had found it hard to categorise symptoms as either, as the difficulties are interrelated. For instance, if a child has limited language (a communication problem) this will almost inevitably limit social interaction.
By what age must symptoms have appeared for diagnostic criteria to be met?For childhood autism (but not for Asperger syndrome) ‘functional impairment’ in social interaction, or in language use for communication, must have appeared by age 3 years. Social communication difficulties and RRBIs must have been present in early childhood; however, ‘functional impairment’ need not be apparent till later.DSM-5 criteria accommodate cases where early childhood symptoms only become apparent later than 3 years of age. This allows for what was formerly Asperger syndrome within a continuum of different developmental profiles.
Sensory problems are common in autism: how are these represented in the criteria?The ICD-10 criteria do not include sensory problems as a formal criterion.DSM-5 includes sensory hyper/hyposensitivities as part of the ‘non-social’ RRBI cluster of symptoms.The evidence that sensory difficulties occur in a majority of autistic people, convinced the DSM-5 working groups to include them as a diagnostic criterion. ICD-11 has done the same.
How are differences in symptoms and severity represented in diagnosis?

Mainly through use of the three sub-diagnoses.

Evaluation of severity (level 1, 2 and 3) is an integral part of the diagnosis.

The DSM-5 severity scores should help clinicians to avoid the confusing informal terms ‘high-functioning’ and ‘low-functioning’.
How are additional problems beyond the main symptom clusters represented?In ICD-10, problems such as epilepsy or dyslexia would be noted as clinical features beyond the main diagnosis.

In DSM-5, problems such as epilepsy, dyslexia or intellectual disability are combined with the individual’s diagnosis as ‘specifiers’ – additional problems which help to characterise the individual's case.

The aim of the DSM-5 specifiers is to make each diagnosis as precise and specific as possible to the individual person. ICD-11 adopts similar principles, but treats autism with and without intellectual disability as distinct sub-diagnoses.

Activity 2 Additional symptoms with significance

Timing: Allow about 5 minutes

From the feedback to Activity 1, can you identify one or more behaviours highlighted by parents but not included within the ICD-10 or DSM-5 core diagnostic criteria?

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Several parents report their children’s sleep problems. Charlotte, George’s mother, mentions his precocious motor development and exceptional memory for words and phrases.