Diagnostic Procedure

Autism spectrum disorders (ASD): diagnosis according to ICD-11/DSM-V

The ICD (International Statistical Classification of Diseases and Related Health Problems of the World Health Organization (WHO)) and the DSM (Diagnostic and Statistical Manual of Mental Disorders, currently 5th version “DSM-V”) are classification systems in which clear and unambiguous criteria for ASD are described. At the beginning of 2022 the German version of the ICD-11 was published, however in the authorities and hospital everyday life the ICD-10 is still valid.

Autism spectrum disorders (ASD) are classified in ICD-10 in Chapter V (Mental and behavioral disorders; F00-F99) under code F84 as profound developmental disorders.

“The terminology of Profound Developmental Disorders was intended to make clear that it is an enduring, severe, multiple domain disorder, thus affecting the entire developmental course.” (Freitag et al., 2017, p. 4)

Not all of the profound developmental disorders listed are part of an autism spectrum disorder. In ICD-10, the following groupings map to ASD:

F84.0 Early childhood autism
F84.1 Atypical autism
F84.5 Asperger syndrome

The ICD-11 refrains from such a clear-cut subdivision, as it was made in the ICD-10, due to the fluid boundaries within the autistic spectrum.

In the DSM-V, which is mainly used in English-speaking countries, autism is already classified under the code 299.00 as an autism spectrum disorder without subgroups. In addition, different degrees of severity of the occurring symptoms are described. The eleventh version of the ICD follows this approach.

In the ICD-11, autism spectrum disorders are classified under the code 6A02. Further information about the classification of an ASD in the ICD-11 can be found under the following link:

https://icd.who.int/browse11/l-m/en#/http%3a%2f%2fid.who.int%2ficd%2fentity%2f437815624

In order to explain the disorder pattern of an ASD, the three-part structure from the ICD-10 is still suitable:

Early childhood autism:

Impaired development before the age of three
Abnormalities in social interaction
Abnormalities in communication
Stereotypical, repetitive behavior patterns and interests

Asperger’s Syndrome:

No language or cognitive developmental delay
Abnormalities in social interaction
Stereotypical and repetitive behavior patterns and interests

Atypical autism:

Impaired development before/at/after the age of three
Abnormalities in social interaction and/or
Abnormalities in communication and/or
Stereotyped, repetitive behavior patterns and interests

The diagnosis of “atypical autism” is problematic from a professional point of view, because it also includes people who do not fulfill the core criteria of autism; it often represents a misdiagnosis.

For a more in-depth discussion of the topic, we recommend the interdisciplinary S3 guidelines of the DGKJP and the DGPPN as well as those of the participating professional societies, professional associations and patient organizations (AWMF 2016). https://www.awmf.org/leitlinien/detail/ll/028-018.html

Implementation of diagnostics

In the diagnostic process, various examinations, screening instruments and clinical test procedures are used. The performance of a differential diagnosis is of particular importance in order to be able to distinguish ASD from other developmental disorders. This means that in addition to the actual examination to diagnose autism, some complementary and adjacent examinations are performed for further clarification and to rule out other explanations for the symptoms and behaviors.

The diagnostic process usually includes the following steps:

medical diagnostics (vision and hearing tests, physical examinations, and human genetic testing if necessary)
anamnesis/psychological examination from the time before birth to current time (autism-specific test procedures, general psychopathology, interviews, disorder-specific diagnostics if necessary)
intelligence/developmental diagnostics (language development tests if necessary)

Medical diagnostics

Since autism often occurs with other disorders or clinical pictures (‘comorbidities’), additional medical examinations may be necessary. These include, for example, the recording of brain waves by EEG, imaging procedures (such as CT and MRI) or chromosome examinations. Possible comorbidities, some of which occur in combination with ASD, are epilepsy, ADHD, obsessive-compulsive disorder, depression, social phobias and intelligence impairment. In some cases these are also differential diagnoses.

Autism-specific diagnostics

In the context of autism-specific diagnostics, standardized test procedures are used as the so-called “gold standard” in addition to the clinical-psychiatric examination. This primarily refers to the ADI-R and ADOS-2. The ADI-R is a very comprehensive diagnostic interview for autism, in which relatives describe the behavior of the affected person, while the ADOS-2 is a diagnostic observation scale for autistic disorders, which describes the behavior in certain situations that differ from the ADOS depending on the age group. (Further Information under Screening Instruments)

Intelligence and developmental diagnostics

In addition to autism-specific diagnostics, supplementary developmental and intelligence tests as well as other specific observation and testing procedures are used. For example, IQ tests such as the WPPSI-III, the HAWIK-IV, or the K-ABC can be used. In the case of non-verbal persons, IQ testing with the SON-R can be used. IQ test scores may be biased in individuals with ASD, particularly due to the following characteristics:

Lack of understanding of instruction and/or language
Lack of reaction and readiness due to unfamiliar environment and new/unpleasant stimuli (overload), such as smells, sounds, light conditions, etc.

If severe irritation or overload is suspected, testing should be discontinued if necessary and repeated at a later time.

Was tun bei Verdacht auf eine Autismus-Spektrum--Störung (ASS)

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