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Autism Subtypes: Understanding the Spectrum

October 2, 2023

Your autistic child’s behavior may not conform to “classic” characteristics described by doctors and research. Does the spectrum have subtypes meaning autism may manifest uniquely according to differing categories? This used to be the case, until an umbrella term, autism spectrum disorders, was introduced.

Autism Subtypes: Understanding the Spectrum

The spectrum nature of autism makes it difficult to diagnose; it also means it is difficult to categorize. Perhaps realizing this, the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM–5; American Psychiatric Association, 2013) merged the subtypes into a single diagnosis called autism spectrum disorders (ASD). While some feel the subtypes were flawed, others feel a single diagnosis of autism spectrum disorders may exclude borderline cases of autism.

Before the DSM-5 replaced the subcategories with a single diagnosis, a patient could be diagnosed with five independent disorders according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000). The subtypes listed under Pervasive Developmental Disorders were: autistic disorder, asperger’s disorder, childhood disintegrative disorder, pervasive developmental disorder not otherwise specified, and Rett syndrome.

Even though these terms are no longer officially used, parents often ask about the subtypes, (particularly asperger’s) as teachers, clinicians, and the media sometimes refer to these categories. A quick description of each subtype will be provided, followed by a discussion of the single diagnosis of autism spectrum disorder and its implications.

Autistic disorder

This category, or subtype, correlates with what was once considered “classic autism.”

Characterized by severe socio-communication challenges and restricted/repetitive behaviors, this was in some cases the most recognizable presentation of autism. 

But how did this classic category differ from the other subtypes? A review of the empirical evidence examining similarities and differences between autistic disorder and asperger’s disorder found few qualitative differences between the two—the findings were consistent with the view (at the time of the review) that both disorders belong on the autism spectrum (Macintosh & Dissanayake, 2004). Opinions and autism research, like this review, helped inform the eventual decision of a single autism diagnosis. For many, however, the disappearance of distinct subtypes of autism proved controversial, this was especially true for the next subtype, asperger’s syndrome.

Asperger’s syndrome

Aspergers lost its status as an official diagnosis when it was absorbed into ASD in 2013. Before that, it was a distinct, official diagnosis often differentiated from other “types” of autism because patients showed no intellectual and verbal delay. Social interaction challenges, however, were present in addition to restricted interests and insistence on sameness. Individuals diagnosed with asperger’s syndrome often displayed impressive strengths in addition to the core characteristics of “classic” autism—remarkable memory feats were frequently reported for this population.

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Many individual’s saw asperger’s as more than a diagnosis, it was and remains an identity. Aspies, or individuals with asperger’s syndrome, were (and still are) part of supportive communities, sharing special interests and offering support. Identifying and finding pride in community should not be dependent on medical labels, many in the autism community still prefer the term aspergers—it implies much more than a diagnosis.

Diagnosing autism with no language delay or intellectual disability

Sometimes autism may be missed in children with high or normal intelligence, the kids previously diagnosed with aspergers, especially those with exceptional verbal skills. These kids may mask their symptoms for social acceptance, camouflaging symptoms by mimicking neurotypical peers. Often these children are only diagnosed later on, or misdiagnosed with related conditions like obsessive compulsive disorder or anxiety. 

Although every child on the spectrum will have different symptoms, some experts believe providing the general characteristics of aspergers may help parents identify autism “red flags” in children who seem to cope with the neurotypical world, at least temporarily. Some of these traits, along with social interaction difficulties and restricted/repetitive behaviors, include:

  • Speaking in a monotone voice, sometimes too loud or too soft, with unusual prosody. Many children with asperger’s syndrome possess normal or exceptional verbal abilities, but for some, concentrating on what they are saying may be prioritized over the way they say it
  • Atypical gait may be observed, in addition to differences in head and trunk posturing (Rinehart et al., 2006)
  • Sensory processing difficulty particularly auditory processing deficits (Dunn et al., 2002)
  • Special interests may be especially intense in this group (Anthony et al., 2013)

The next category, pervasive developmental disorder not otherwise specified, seemed to occupy a space somewhere between autistic disorder and aspergers on the spectrum.

Pervasive developmental disorder not otherwise specified (PDD-NOS)

Autism research found children with PDD-NOS displayed “levels of functioning” somewhere between kids with classic autism and those with asperger’s syndrome—interestingly, the research showed those with PDD-NOS had fewer repetitive stereotyped behaviors than children in the other two groups (Walker et al., 2004).

This category (PDD-NOS) did not have specific criteria, this may be the reason it became a catch-all diagnosis for children who did not fit neatly into any of the other subtypes or autism categories (Filipek et al., 1999). This subtype confirms why a single autism diagnosis, with symptoms on a wide spectrum, needed to be considered. On the other hand, a catch-all category probably ensured children with unusual presentations of autism received support and appropriate intervention.

Childhood disintegrative disorder

Also referred to as Heller’s syndrome and disintegrative psychosis, the disorder was characterized by a period of normal development in all areas—at least two years—followed by a period of irreversible loss of such acquired skills leading to significant intellectual disability (Charan, 2012).

Regression has always been associated with autism, but for this subtype it is the defining characteristic. There is some debate whether childhood disintegrative disorder (CDD) differs from autism with regression. Literature does suggest later onset of CDD in comparison to autism, this and other differences may be the reason many experts feel the disorder merits a separate diagnosis. It is currently incorporated under the larger developmental disorder category, autism spectrum disorder, along with the other subtypes.

Rett syndrome

Rett syndrome is a progressive and rare neurological and developmental disorder primarily affecting girls. The genetic disorder affects brain development, causing physical and intellectual disability. Symptoms appear around 6-18 months; many of these symptoms like lack of eye contact, social withdrawal and communication impairments are similar to symptoms displayed by children on the autism spectrum. 

The disorder was probably included in the DSM-4 because of its many autistic features. But since the genetic cause has been established for Rett syndrome, the disorder has become a distinct entity, no longer specifically included in the DSM-5 as an ASD. Children with Rett syndrome will therefore have to meet the DSM-5 diagnostic criteria to be diagnosed with autism. 

Autism Spectrum Disorders

After much debate and controversy, the subtypes were collapsed into autism spectrum disorders in 2013. The umbrella term, or single diagnostic label, emphasizes the significance of the spectrum. 

Each individual with autism will present symptoms differently, a wide spectrum means variability in manifestation can be accommodated. Furthermore, if a child does not fit into a specific subtype, but displays the core characteristics of autism (social communication difficulties and restricted/repetitive behaviors) they could still receive a diagnosis and appropriate support.

The width of the spectrum promotes inclusivity, but some feel defined categories of autism translate to more focused research and appropriate support for individuals with distinct needs. While most advocates agree “high and low functioning” descriptors should be abandoned, they do share the hope of studies and specific, scientifically backed intervention for those with specific support needs, for example, communication support for the nonspeaking pediatric population. 

Whether parents refer to symptoms listed in subtypes of autism in the DSM-IV-TR (DSM-4) or core characteristics of ASD according to the DSM-5, any red flags should prompt an immediate consultation with a pediatrician or child psychiatrist. Wherever a child falls on the spectrum, early intervention and support will contribute to parents ultimate goal for their child, the best possible quality of life.


American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author.

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596

Anthony, L. G., Kenworthy, L., Yerys, B. E., Jankowski, K. F., James, J. D., Harms, M. B., Martin, A., & Wallace, G. L. (2013). Interests in high-functioning autism are more intense, interfering, and idiosyncratic than those in neurotypical development. Development and psychopathology, 25(3), 643–652. https://doi.org/10.1017/S0954579413000072.

Charan S. H. (2012). Childhood disintegrative disorder. Journal of pediatric neurosciences, 7(1), 55–57. https://doi.org/10.4103/1817-1745.97627.

Dunn, Winnie & Myles, Brenda & Orr, Stephany. (2002). Sensory Processing Issues Associated With Asperger Syndrome: A Preliminary Investigation. The American journal of occupational therapy : official publication of the American Occupational Therapy Association. 56. 97-102. 10.5014/ajot.56.1.97.

Filipek, P. A., Accardo, P. J., Baranek, G. T., Cook, E. H., Jr, Dawson, G., Gordon, B., Gravel, J. S., Johnson, C. P., Kallen, R. J., Levy, S. E., Minshew, N. J., Ozonoff, S., Prizant, B. M., Rapin, I., Rogers, S. J., Stone, W. L., Teplin, S., Tuchman, R. F., & Volkmar, F. R. (1999). The screening and diagnosis of autistic spectrum disorders. Journal of autism and developmental disorders, 29(6), 439–484. https://doi.org/10.1023/a:1021943802493.

Macintosh, K. E., & Dissanayake, C. (2004). Annotation: The similarities and differences between autistic disorder and Asperger’s disorder: a review of the empirical evidence. Journal of child psychology and psychiatry, and allied disciplines, 45(3), 421–434. https://doi.org/10.1111/j.1469-7610.2004.00234.x.

Rinehart, N. J., Tonge, B. J., Bradshaw, J. L., Iansek, R., Enticott, P. G., & McGinley, J. (2006). Gait function in high-functioning autism and Asperger’s disorder : evidence for basal-ganglia and cerebellar involvement?. European child & adolescent psychiatry, 15(5), 256–264. https://doi.org/10.1007/s00787-006-0530-y

Walker, D. R., Thompson, A., Zwaigenbaum, L., Goldberg, J., Bryson, S. E., Mahoney, W. J., Strawbridge, C. P., & Szatmari, P. (2004). Specifying PDD-NOS: a comparison of PDD-NOS, Asperger syndrome, and autism. Journal of the American Academy of Child and Adolescent Psychiatry, 43(2), 172–180. https://doi.org/10.1097/00004583-200402000-00012.

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