What Are the 5 Different Types of Autism?

Autism spectrum disorder (ASD) includes the word ‘spectrum’ for a reason, since autism can manifest in very different ways that are measured along a  spectrum. The autism spectrum marks the degrees of severity with which an adult or child is affected by their ASD diagnosis.

Today, the term ASD is broadly used to refer to any person who falls along this spectrum. But in the past, the medical world used 5 different types of autism to identify a patient’s diagnosis. Though these types of autism are no longer technically diagnosed, many still use them to classify and understand their or their loved one’s diagnosis.

Different Forms of Autism

These 5 different types of autism mark the degree of difficulty to which an autistic person experiences and interacts with the world around them. These interactions can be social, verbal, and communicative.

Aspergers Syndrome

Up until 2013, Aspergers Syndrome was the commonly applied term to describe what is now known as level 1 ASD. The term was officially switched out in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Though it is no longer used by medical professionals, some adults with autism may still use it unofficially.

Aspergers is typically used to refer to a “less severe” subtype of ASD, otherwise known as high-functioning autism. People with level 1 ASD typically display above-average intelligence and will even excel academically. Often they will struggle to develop social and communicative skills, which may become a significant obstacle as they grow older.

Signs of Asperger’s syndrome or level 1 ASD include:

  • Singular fixations on single topics, hobbies, and/or activities that can border on obsession, and can disrupt everyday life
  • Difficulty in social interactions, particularly reading facial expressions and body language and detecting sarcasm and irony
  • Frustration when routines are disrupted
  • Difficulty with emotional regulation
  • Impressive ability to retain information that interests them

Childhood Disintegrative Disorder

CDD, otherwise known as Heller’s syndrome, is another former disorder that has been subsumed by the ASD diagnosis. It is a particularly rare form of autism, and though it shares many similarities to other types, it is defined by its late onset. Children with CDD will develop normally in their early years until the onset of CDD, which occurs anywhere between the ages of 3 to 10. It includes the regression of motor function, and language and social abilities.

Symptoms of Childhood Disintegrative Disorder Includes:

  • Sudden lack of development in areas such as language, social skills, and communication
  • Gradual or sudden loss of motor skills, verbal communication, self-care, social ability, etc
  • Developed fear or dislike of physical contact
  • Hallucinations involving sight, smell, and hearing

Classical Autism

Also known as Kanner’s syndrome, classical autism is the broadest form of autism, classified in 1943 by psychiatrist Leo Kanner. Initially identified as “infantile autism,” classical autism was once used to diagnose children who exhibited general autistic tendencies, such as unusually high intelligence and attentiveness, alongside traits such as:

  • Struggles with interpersonal communication
  • Exceptional rote memory
  • Attachment to specific objects
  • Difficulty forming emotional attachments to people
  • Deficits in language skills along with difficulty controlling speech and unusual speech patterns

Of these 5 types of autism, it is the closest to being interchangeable with what we now call Autism Spectrum Disorder.

Rett’s Syndrome

A neurodevelopmental disorder that almost exclusively affects girls and women, Rett’s syndrome exhibits very similar symptoms to autism spectrum disorder. Though it was once included under the umbrella of autism, it has since been removed as it largely affects only women and exhibits physical symptoms that are not present in people with autism.


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Instead, Rett’s syndrome is now believed to be the result of a genetic mutation that presents itself in 4 stages, though onset and severity of symptoms will vary. Symptoms of Rett’s syndrome can include:

  • Loss of co-ordination and mobility
  • Seizures
  • Scoliosis
  • Difficulty speaking and understanding language
  • Breathing difficulties
  • Involuntary movements (particularly of the hands)

Pervasive Development Disorder – Not Otherwise Specified

One of the three main types of autism, PDD-NOS was used to describe people who do not fit into any of the aforementioned categories of autism. These are people who fulfill some of the criteria of classical autism, but not all. Their autism symptoms are typically milder than usual and can be described as moderate to high-functioning autism.

Impairments for those with PDD-NOS will come under autism levels 1 and 2.

Though these types of autism are no longer recognized as official diagnoses by medical professionals, they are still used informally, and can help people with ASD to better understand where they sit on the autism spectrum.

If your child or loved one has been diagnosed with autism spectrum disorder, and you are in need of further resources to understand and manage their diagnosis, we can help. Our team at Bolling ABA provides professional personalized treatment for children and adults with autism and related disorders. You can email us or call 404.981.4105 to book your first free consultation.

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