5 Types of Autism Spectrum Disorder

Discover the types of Autism Spectrum Disorder, their diagnosis, and treatment approaches for better understanding.

judah schiller
Judah Schiller
May 1, 2024
Published On
May 1, 2024

Understanding Autism Spectrum Disorders

What is Autism Spectrum Disorder?

Autism Spectrum Disorder (ASD) is a neurological and developmental disorder that primarily affects an individual's ability to interact with others, communicate, learn, and behave. Although ASD can be diagnosed at any age, it is often referred to as a "developmental disorder" because symptoms typically emerge within the first two years of life [1].

ASD is known as a "spectrum" disorder due to the broad variation in the type and severity of symptoms individuals may experience. It's a lifelong condition, affecting individuals differently and to varying degrees [2].

Research is still underway to uncover the primary causes of ASD, but studies suggest that a combination of a person's genes and their environment can influence development in ways that lead to ASD [1].

Symptoms of Autism Spectrum Disorder

People with ASD often experience impairments in social interaction and communication. They may exhibit restricted and repetitive patterns of behavior, interests, or activities, and may have sensory sensitivities.

Treatment for ASD should ideally start as soon as possible after diagnosis. Early intervention is crucial as it can help reduce difficulties, allowing individuals to build on their strengths and learn new skills. Options for treatment may range from medication to behavioral, psychological, and educational interventions.

ASD is a complex disorder with no known cure, but with early intervention and appropriate support, the quality of life for individuals with ASD and their families can be greatly improved. Treatment approaches may include behavioral therapy, speech-language therapy, play-based therapy, physical therapy, occupational therapy, and nutritional therapy.

This introduction to ASD lays the groundwork for understanding the various types of autism spectrum disorders and their symptoms, providing a necessary context for delving into the intricate details of each type.

The Major Types of Autism

Diving into our exploration of the diverse types of autism spectrum disorder, we find five major types: Asperger’s syndrome, Rett syndrome, childhood disintegrative disorder, Kanner’s syndrome, and pervasive developmental disorder – not otherwise specified. Each of these disorders is unique and presents its own set of characteristics and challenges.

Asperger’s Syndrome

Asperger’s syndrome, now considered level 1 autism spectrum disorder, is characterized by above-average intelligence, strong verbal skills, and challenges with social communication. People with Asperger’s are often very intelligent and able to handle daily life, but they struggle socially. The syndrome also involves an intense focus on topics of interest [4].

Rett Syndrome

Rett syndrome is a rare neurodevelopmental disorder affecting mostly girls, but it can also be diagnosed in boys. This disorder presents challenges in various aspects of a child's life, including language and motor skill development, and social interaction [3].

Childhood Disintegrative Disorder

Childhood disintegrative disorder (CDD) is a neurodevelopmental disorder where a child experiences normal development up to age three and then encounters significant regressions in language, motor skills, or social function. It's the rarest and most severe part of the spectrum, often accompanied by a seizure disorder, typically manifesting between ages 2 and 4.

Kanner’s Syndrome

Kanner’s syndrome, also known as autistic disorder, is on the more intense end of the autism spectrum. Symptoms are similar to Asperger’s and PDD-NOS, but at a more severe level. This disorder is characterized by significant difficulties in social interaction and communication, along with restricted and repetitive patterns of behavior and interests.

Pervasive Developmental Disorder – Not Otherwise Specified

Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS) is a diagnosis for children whose autism is more severe than Asperger's, but not as severe as autistic disorder. Individuals with PDD-NOS may experience delays in language development, walking, and other motor skills, with the most common symptoms being challenges in social and language development.

In understanding the vast spectrum of autism, it is crucial to recognize the unique characteristics and challenges each type presents. This exploration of the major types of autism spectrum disorder helps us appreciate the complexity and diversity of this condition. An accurate diagnosis is crucial for implementing suitable interventions and therapies.

Characteristics of Each Autism Type

In order to understand autism more fully, it's useful to understand the different types of autism spectrum disorder and their associated characteristics. These types include Asperger’s Syndrome, Rett Syndrome, Childhood Disintegrative Disorder, Kanner’s Syndrome, and Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS).

Asperger’s Syndrome Traits

Asperger's syndrome, now classified as Level 1 Autism Spectrum Disorder, is characterized by above-average intelligence, strong verbal skills, and challenges with social communication. Individuals with Asperger's syndrome may be very intelligent and able to manage daily life, but they struggle socially. This condition involves intense focus on topics of interest [4].

Common traits include:

  • Above-average intelligence
  • Strong verbal skills
  • Social communication challenges
  • Intense focus on specific topics of interest

It's important to note that the term "Asperger's syndrome" is still used by many, even though it is no longer a standalone diagnosis. Some individuals who received the Asperger syndrome diagnosis prior to 2013 still use the term as part of their identity, while others prefer to refer to themselves as autistic. Both perspectives are considered correct, reflecting personal choice.

Rett Syndrome Features

Rett syndrome is a rare genetic disorder that mostly affects girls. It's characterized by normal early growth and development followed by a slowing of development, loss of purposeful use of the hands, distinctive hand movements, slowed brain and head growth, problems with walking, seizures, and intellectual disability.

Common features include:

  • Slowing of development
  • Loss of purposeful use of hands
  • Distinctive hand movements
  • Slowed brain and head growth
  • Problems with walking
  • Seizures

Childhood Disintegrative Disorder Symptoms

Childhood disintegrative disorder, also known as Heller's syndrome, is a rare condition characterized by late onset of developmental delays—or severe and sudden reversals—in language, social function, and motor skills. Researchers have not been able to find a cause for the disorder.

Symptoms include:

  • Late onset of developmental delays
  • Severe and sudden reversals in language
  • Social function challenges
  • Motor skills difficulties

Kanner’s Syndrome Characteristics

Kanner's syndrome, also known as classic autistic disorder, is characterized by significant issues with social interaction and communication, a limited range of activities and interests, and often repetitive behaviors.

Characteristics include:

  • Significant issues with social interaction and communication
  • Limited range of activities and interests
  • Often repetitive behaviors


Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS) was once used to refer to individuals who are on the autism spectrum but do not fully meet the criteria for another ASD diagnosis. This term is no longer widely used.

Signs include:

  • Challenges with social interaction and communication
  • Stereotyped behaviors
  • Interests and activities that are restricted
  • Symptoms that cause significant social, occupational, or other impairments

Diagnosis and Evolution of Autism

Understanding the diagnosis and evolution of autism is key to comprehending the various types of autism spectrum disorder. This understanding has evolved over time, with significant changes in diagnostic categories and a notable transition from DSM-4 to DSM-5.

Changes in Diagnostic Categories

In the DSM-4, autism was divided into five separate diagnoses: Autistic Disorder, Asperger’s Disorder, Rett’s Disorder, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS). This approach helped clinicians understand the distinctive aspects of each diagnosis, but it also led to confusion due to overlapping symptoms and criteria.

Transition from DSM-4 to DSM-5

Recognizing the challenges with the DSM-4 classification, the DSM-5 redefined autism as Autism Spectrum Disorder (ASD) without subcategories. This change reflects the understanding that autism is a spectrum condition with symptoms that vary in severity. If someone had a diagnosis of Asperger’s, Autistic Disorder, or PDD-NOS from the DSM-4, they would likely be considered as having ASD in the DSM-5.

Level 1, Level 2, and Level 3 Autism

With the transition to DSM-5, Autism Spectrum Disorder (ASD) is now categorized into three distinct levels based on the severity of symptoms and the amount of support needed in everyday life, labeled as ASD Level 1, ASD Level 2, or ASD Level 3.

Level 1 Autism

Level 1 Autism, considered the mildest form, is characterized by the ability to communicate verbally using words and more complex language compared to individuals with Level 3 autism. People with Level 1 autism often struggle with aspects of communication, social interactions, and transitions involved in changing activities.

Level 2 Autism

While the specifics of Level 2 Autism are not detailed in the extra context, it can be inferred that it falls between Level 1 and Level 3 in severity. Individuals with Level 2 Autism would require more support than those with Level 1 Autism but less than those with Level 3 Autism.

Level 3 Autism

Level 3 Autism, the most severe, is characterized by the need for very substantial support in daily life, having challenging behaviors like frequent meltdowns, aggression, or self-harm, difficulty understanding others, and needing more supervision even as an adolescent or adult compared to Level 1 or 2 Autism [6].

In conclusion, the diagnosis and evolution of autism have significantly changed over time, shedding light on the complex nature of autism spectrum disorders. This evolution underscores the importance of understanding autism as a spectrum and tailoring interventions to meet the unique needs of each individual.

Treatment Approaches for Autism

A comprehensive understanding of the types of Autism Spectrum Disorder (ASD) is not complete without delving into the various treatment approaches available. These treatments and interventions are designed to aid individuals with ASD in developing necessary life skills, reducing symptoms, and improving overall quality of life. Common autism treatments include behavior therapy, speech-language therapy, occupational therapy, pharmacological interventions, and psychological counseling. Often, a combined treatment approach that incorporates several different types of therapy is necessary.

Behavioral Therapy

Behavior therapy is a commonly used ASD treatment that aims to encourage desired behaviors and reduce unwanted behaviors. Applied Behavior Analysis (ABA) is a commonly used technique in behavior therapy that encourages desired behaviors and discourages undesired behaviors to improve a variety of skills. Progress is tracked and measured, with a focus on teaching styles such as Discrete Trial Training (DTT) and Pivotal Response Training (PRT) [8].

The Early Start Denver Model (ESDM) is an approach that works best for 12- to 48-month-olds and follows the practices of ABA. ESDM focuses on creating positive social interactions, enhancing communication and cognitive skills.

Speech and Language Therapy

Speech and Language Therapy aims to improve specific developmental skills such as language or broader developmental abilities. This developmental approach is particularly beneficial for children with ASD who have difficulty communicating or understanding others. It can also help with non-verbal communication, such as using hand gestures or visual aids.

Occupational Therapy

Occupational Therapy is designed to teach skills for independent living, such as dressing, eating, and relating to people. It's tailored to match the individual's needs and can help with various tasks, such as improving coordination, organizing schoolwork, or even job skills for adults.

Pharmacological Interventions

Pharmacological approaches do not treat the core symptoms of ASD but are used to manage co-occurring symptoms such as high energy levels, inability to focus, self-harming behaviors, anxiety, depression, seizures, sleep problems, or gastrointestinal issues. Working with a doctor experienced in treating ASD is essential to monitor progress and reactions to medication [8].

Psychological Counseling

Psychological approaches like Cognitive-Behavior Therapy (CBT) help individuals with ASD cope with anxiety, depression, and other mental health issues. CBT focuses on identifying goals and changing how an individual thinks about a situation to modify their reactions.

It is crucial to remember that treatment plans need to be individualized to fit the unique needs of each person with ASD, as what works for one might not work for another. Working with a team of professionals who understand the nuances of ASD can ensure that the chosen treatments will effectively address the individual's symptoms and challenges.

Controversies and Historical Context

In the world of psychology and psychiatry, debates and controversies often arise, especially when it comes to diagnoses and classifications. One such debate revolves around Asperger's syndrome and its place within the types of autism spectrum disorder.

Asperger’s Syndrome Controversy

Asperger's Syndrome, named after Dr. Hans Asperger, has been the subject of controversy due to the historical context of its discovery and the implications of its use. During the 1940s, Asperger was the first to recognize social issues in children that now define Asperger’s syndrome. However, there is controversy surrounding his research, as it is debated whether his work promoted forced “race hygiene” under Nazi policies that targeted individuals with disabilities. New research suggests that the label of Asperger’s syndrome may have harmed people and contributed to some children’s deaths.

Hans Asperger and Asperger’s Syndrome

Hans Asperger was a doctor in Vienna who, during the 1940s, first identified a set of behaviors that are now recognized as Asperger’s syndrome. His work focused on children who exhibited social difficulties, repetitive behaviors, and narrow interests, which are now seen as key characteristics of this condition. However, the historical context of Asperger's work, during a time when eugenic policies were enacted, has sparked debates and controversy.

Evolution of Asperger’s Diagnosis

Initially, Asperger's syndrome was considered a separate condition from autism. However, the 2013 edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) reclassified it as part of the broader autism spectrum disorder (ASD). Despite its official reclassification, the term "Asperger's" is still used by many people, and it is no longer a standalone diagnosis [9].

The symptoms of Asperger's syndrome typically begin early in life, with most diagnoses occurring between ages 5 and 9. However, some individuals are not diagnosed until adulthood. The symptoms vary from person to person but are usually related to emotional, communication, and behavioral skills.

The reclassification of Asperger's syndrome in 2013 into the broader autism spectrum disorder (ASD) diagnosis in the DSM-5, now the DSM-5-TR, has led to varied responses from individuals who received the Asperger syndrome diagnosis prior to 2013. Some still use the term as part of their identity, while others prefer to refer to themselves as autistic. Both perspectives are considered correct, reflecting personal choice.

In understanding the types of autism spectrum disorder, it's important to acknowledge these controversies and the evolution of diagnoses. It provides a lens through which to view the current understanding and treatment of autism.


[1]: https://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd

[2]: https://www.helpguide.org/articles/autism-learning-disabilities/autism-spectrum-disorders-asd

[3]: https://www.integrityinc.org/what-are-the-5-types-of-autism/

[4]: https://www.webmd.com/brain/autism/autism-spectrum-disorders

[5]: https://www.autismspeaks.org/asperger-syndrome

[6]: https://behavioral-innovations.com/blog/types-and-levels-autism-spectrum-disorder/

[7]: https://www.helpguide.org/articles/autism-learning-disabilities/autism-treatments-therapies-interventions.htm

[8]: https://www.cdc.gov/ncbddd/autism/treatment.html

[9]: https://www.webmd.com/brain/autism/mental-health-aspergers-syndrome