Atypical autism: what is it and what subgroups exist?

Diagnostic classifications categorize autism spectrum disorders in different ways. Thus, the DSM-5 eliminates the distinction between Kanner's or classic autism, Asperger's syndrome, of Rett and childhood disintegrative disorder present in the fourth edition of the manual, while ICD-10 includes the diagnosis of "atypical autism".

In this article we will explain the basic characteristics of this variant of autistic disorder. The diagnostic category is used primarily to describe forms of autism in which symptoms are mild, uncommon, or simply not present in all areas, or the age of onset does not correspond to the classical one.

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autism spectrum disorders

Autism spectrum disorders are characterized by deficits in communication and social interaction and alterations in behavior patterns; Specifically, repetitive behaviors and restricted interests tend to occur. Intellectual functional diversity, developmental delays, and sensory problems also appear frequently.

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is used as a reference by many clinical psychologists but has received a great deal of criticism, redefined the pervasive developmental disorders described in the DSM-IV in a single category: Autism Spectrum Disorder.

Both the DSM-IV and the tenth edition of the International Classification of Diseases (ICD-10) divide autism spectrum disorders or disorders Pervasive developmental disorders in different diagnoses: childhood autism or autistic disorder, Asperger and Rett syndromes, and disintegrative childhood.

Both classifications also include an extra category; in the case of the DSM-IV it is the catchall “Pervasive developmental disorder not otherwise specified”, which roughly corresponds to the diagnosis of “atypical autism” described in the ICD-10. Let's see what this disorder consists of.

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What is atypical autism?

ICD-10 defines atypical autism as a pervasive developmental disorder that does not meet diagnostic criteria for autism; this includes cases in which symptoms and deficits manifest after the age of 3 or do not occur at all three classic areas of autism: social interaction, communication, and restricted, repetitive, or stereotyped.

According to this manual, atypical autism appears above all in people with severe intellectual deficits whose low level of functioning prevents them from certain behaviors, as well as in others with severe language disorders receptive. As we will see later, the research suggests that these cases can be classified into three distinct subgroups.

There is some debate about the specific characteristics of this form of autism. While some experts describe it as a mild variant of classic autism, others consider that its clinical characteristics and the relationship with other alterations make atypical autism deserve to be considered as a differentiated disorder.

In general, it seems that the studies indicate that the average severity of the cases of atypical autism would be between that of classic autism and that of Asperger syndrome, which is associated with better social functioning and cognitive. However, given its diagnostic characteristics, atypical autism is an entity made up of very diverse cases.

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Atypical Autism Subgroups

A study by Walker et al. (2004) published in the Journal of the American Academy of Child & Adolescent Psychiatry” compared the level of functioning of children with autistic disorder, Asperger syndrome and autism atypical.

This research team identified three distinct subgroups who met the diagnostic criteria for classic autism, in addition to finding that in general it is a mild variant of classic autism.

1. With limited stereotypes

The most common subgroup of atypical autism, encompassing more than 50% of cases, is girls and boys who meet all the diagnostic criteria for autistic disorder but present with reduced signs in the area of ​​repetitive behaviors. This means that the social deficits are much more significant than the stereotypes and the restriction of interests.

2. Incomplete Autism Criteria

According to this research, 25% of people with atypical autism present symptoms and signs in the three areas relevant to the diagnosis (communication, interaction and stereotyped behaviors), although they are not marked enough to meet the criteria. This subgroup would include many cases of autism with severe intellectual deficit.

3. high functioning

The third set of cases bears similarities to Asperger syndrome: characterized by relatively normal language functioning, but cannot be performed this diagnosis because there is a delay in linguistic development and/or cognitive deficits relevant. The proportion of this subtype is also about 25%.

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