Atypical autism: what is it and what subgroups of this disorder are there?

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

In this article, we will explain the basic characteristics of this variant of autism disorder. The diagnostic category is particularly useful for describing forms of autism in which symptoms are mild, rare, or just do not appear in all areas, Or the age of onset does not correspond to the classic.

    Autism spectrum disorders

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

    The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is used as a benchmark by many clinical psychologists but has received much criticism, redefined the prevalent developmental disorders described in DSM-IV a only one category: autism spectrum disorders.

    The DSM-IV and the tenth edition of the International Classification of Diseases (ICD-10) divide autism spectrum disorders or generalized developmental disorders into different diagnoses: childhood autism or autism disorder, Asperger’s syndromes and disintegration disorder. Rett and childhood.

    Both classifications also include an additional category; in the case of the DSM-IV it is the tailor’s drawer “Generalized developmental disorder not specified”, which corresponds broadly to the diagnosis of “atypical autism” described in ICD-10. Let’s see what this disorder is.

      What is atypical autism?

      The ICD-10 defines atypical autism as a common developmental disorder that does not meet diagnostic criteria for autism; this includes cases where symptoms and deficits appear after the age of 3 or do not appear in the three classic areas of autism: social interaction, communication, and restricted, repetitive or stereotypical behavior.

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

      There is a debate around the specific characteristics of this form of autism. while some experts describe it as a mild variant of classical autism, others consider its clinical features and its relationship to other disorders to make atypical autism worthy of being considered a differentiated disorder.

      Overall, it seems that studies indicate that the average severity of atypical autism cases is between that of classic autism and that of Asperger’s syndrome, which is associated with better social and cognitive functioning. However, given its diagnostic characteristics, atypical autism is an entity made up of a wide variety of cases.

        Atypical autism subgroups

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

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

        1. With limited stereotypes

        The most common subgroup of atypical autism, encompassing more than 50% of cases, are girls and boys who meet all diagnostic criteria for autism disorder but have reduction of signs in the area of ​​repetitive behavior. This means that the social deficits are much more important than the stereotypes and the restriction of interests.

        2. Incomplete autism criteria

        According to this research, 25% of people with atypical autism have it symptoms and signs in the three areas relevant to the diagnosis (Communication, interaction and stereotypical behaviors), although they are not sufficiently marked to meet the criteria. This subgroup would include many cases of autism with severe intellectual disability.

        3. High performance

        The third set of cases has similarities to Asperger’s syndrome: It is characterized by a relatively normal functioning of the language, but this diagnosis cannot be made because there is a delay in the development of the language and / or relevant cognitive deficits. The proportion of this subtype is also around 25%.

          Bibliographical references:

          • American Psychiatric Association (2002). DSM-IV-TR Diagnostic and Statistical Manual. Barcelona: Masson.
          • American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders: DSM-5. Washington, DC: American Psychiatric Association.
          • World Health Organization (2003). CIE-10. Clinical descriptions and diagnostic guidelines. Madrid: mediator.
          • Walker, DR, Thompson, A., Zwaigenbaum, L., Goldberg, J., Bryson, SE, Mahoney, WJ & Szatmari, P. (2004). PDD-NOS specification: a comparison of PDD-NOS, Asperger’s syndrome, and autism. Journal of the American Academy of Child and Adolescent Psychiatry, 43 (2), 172-180.

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