Asperger syndrome (AS) was first described by Hans Asperger in 1944, as the behavioral characterization of individuals who have difficulties in communication and social interaction.[1] Since then, AS has always been a topic of significant interest and debate. Although AS was introduced as a discrete diagnostic category in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-4, 1994), almost 20 years later, its diagnostic label was removed in the Diagnostic and Statistical Manual of Mental Disorders (DSM–5), and it was encompassed in a more general category of autism spectrum disorders (ASD).[2] According to the DSM-5, there are varying degrees of ASD that are categorized based on the severity of symptoms and the required levels of support, and what was formerly called Asperger syndrome shall now be regarded as ASD.[3] Autism spectrum disorders (ASD) include a group of neurodevelopmental abnormalities with broadly varying degrees and manifestations, usually begin in early childhood, and characterized by problems in social communication and interaction, along with behavioral problems such as restricted interests and repetitive behaviors.[4][5] DSM-5 changes on ASD classification led to some controversy about the loss of the unique Asperger identity,[6] and literature continue to debate about AS and its formulation within ASD.[7] Due to Asperger syndrome's extensive history, rich semiology, and relatively characteristic clinical presentations, specialists continue to use this diagnosis as a subtype of ASD with no language delay and a normal or superior IQ.[6] In this topic review, we will describe the essential aspects of autism spectrum disorder and Asperger syndrome. For greater transparency, we refer to (1) Asperger syndrome (AS) as a subpopulation of pervasive developmental disorders (PDD) according to DSM-IV-TR, (2) ASD according to DSM-5, and (3) Autism spectrum disorder of an Asperger syndrome type (ASD-AS) as a subpopulation that is included in the DSM-5 as ASD of level 1 severity without intellectual impairment.
Historical Perspective
In 1944, and about a year after Leo Kanner described infantile autism, Hans Asperger introduced autistic psychopathy in the form of a case report. In 1980, the American Psychiatric Association (APA) recognized autism as a distinct category in the DSM-3 and introduced it as infantile autism. In 1981, Wing L. restarted Asperger researches and renamed autistic psychopathy as Asperger syndrome. A few years later and in 1989, the first diagnostic criteria for AS was proposed,[7] and the 10th Revision of the International Classification of Diseases (ICD-10) was the first major classification system that recognized AS (1993). Finally, in 1994, AS was introduced in DSM-4 as a specific entity along with autistic disorder, within pervasive developmental disorders (PDD). While during this period, researches were focused on the development of measures with the ability to diagnose AS and differentiate it from high functioning autism (HFA), the DSM-5 removed the diagnostic category of AS in 2013.[5] The World Health Organization (WHO) also followed a similar approach in ICD-11, which will come into effect in 2022.[2]
DSM Classification
The systematic description of psychiatric disorders is quite complicated, particularly in child and adolescent psychiatry. Asperger syndrome was included in the DSM-IV-TR in the large family of pervasive developmental disorders (PDD). PDD had five subtypes: Autistic disorder. Asperger syndrome. Childhood disintegrative disorder. Pervasive developmental disorder-not otherwise specified (PDD-NOS). Rett syndrome. Symptoms and clinical specifiers for autistic disorder of PDD were described to fall into three broad categories in DSM IV-TR: (1) social interaction, (2) communication, and (3) restricted, repetitive behavior.[8] The diagnosis of AS required:[7]: At least two symptoms of social interaction impairment and at least one each from symptoms of communication and restricted, repetitive behavior (RRB). Delays or abnormal functioning in at least one of the areas of (1) social interaction, (2) language as used in social communication, or (2) symbolic or imaginative play with onset prior to age 3 years. Diagnostic criteria for autistic disorder (or another specific PDD) should not be met (otherwise, the AS diagnosis is excluded, and autistic disorder diagnosis should have precedence). AS contrasted from autistic disorder in:[9]: Absence of diagnostic criteria in the communication domain. Absence of a requirement for onset before age 3. Addition of criteria specifying the absence of a language delay. Addition of criteria specifying the absence of a deficit in cognitive development. This classification suggested a differential diagnosis between AS and the type of Autistic disorder associated with normal cognitive functioning, also known as high functioning autism (HFA). As a result, it sparked substantial debate over uncertainty in defining AS criteria and the clinical overlap between AS and HFA, which has appeared in literature with contradictory results. Although there has been a considerable number of researches showing some fine differences between the two disorders, most studies have emphasized the meaningful similarities between AS and HFA. Ultimately, the DSM-5 removed PDD and its categorization and merged four of its subtypes into one unifying category with the concept of a continuum named autistic spectrum disorders (ASD). This major alteration was mostly due to the assumption that PDD subgroups cannot be differentiated from one another certainly and reliably.[7] These changes include the following:[2][8] Another major alteration was the inclusion of social communication and social interaction related deficits in one criterion and exclusion of deficit specifically related to spoken language. Elimination of PDD and its subtypes. Creation of a new diagnostic category called autistic spectrum disorders (ASD), encompassing autistic disorder, Asperger syndrome, childhood disintegrative disorder, and PDD-NOS. Addition of three levels of severity, and clinical specifiers about the presence of cognitive and language impairment, to better characterize the diagnosis. Changing from previous PDD 3-domain criteria to ASD 2-domain criteria, composed of impaired social communication/interaction and restricted, repetitive behavior, interest, and activities (merging domains of social interaction and communication). Addition of sensory symptoms in the RRB component of diagnostic criteria. Changing the specification of the age of onset from age 3 to "early childhood.". Creation of a new diagnostic category called "social communication disorder" (SCD) to include individuals who have difficulties in social communication/interaction but do not meet RRB criteria found in ASD. Removal of Rett syndrome from the classification, on the basis of recent genetic data.
Controversy over the New Classification of ASD
The new classification of ASDs has been criticized in the literature in different ways. Some authors have suggested that the new classification will narrow the criteria for ASD; thus, some patients may no longer meet the criteria for ASD, in particular, cognitively able individuals and individuals diagnosed with AS and PDD-NOS. In short, the argument is although this reduced sensitivity is associated with higher specificity, it has the potential to exert negative effects on the service eligibility, as well as the ability of researchers to integrate information and data from researches conducted under these criteria.[9][6] Other authors claim that the elimination of the specific diagnostic category for Asperger syndrome will increase stigma towards individuals previously diagnosed with AS, based on the assumption that autism-phobic societies perceive autism as a significant disability, whereas AS is associated with the more positive stereotypes.[10][2] In addition, previous research has demonstrated the association of autism with disability and dysfunction, and the association of AS with positive features. Thus, the new inclusion of AS in the category of ASD may have a negative effect on the identity of the individuals who have adopted this label as an identity. However, the literature on the potential impact of the DSM-5 changes on individuals previously diagnosed with AS is limited, and the results can be categorized into those who are supportive, those who are opposed, and those who express mixed feelings concerning the changes.[2]