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What are the Three Types of Autism Spectrum Disorders?

Just like there is more than one type of anxiety disorder, diabetes, or developmental disorder, there is more than one type of autism. In anxiety, for example, there are five completely separate types, each with their own symptoms, some unique to the other types and some types sharing similar symptoms on a spectrum. Autism Spectrum Disorder (ASD) is considered the broad term for autism, but there are actually three separate sub-types that fit within the ASD category. 

When you think about a ‘spectrum,’ think of seeing different shades of blue all together in one band. All of the shades are technically ‘blue,’ but they range from lightest to darkest. You can also think of a rating scale with two extremes or opposite points. The term ‘autism spectrum disorder’ should be viewed similarly; there is a ‘spectrum’ of symptoms that someone with autism can exhibit, ranging from mild to severe. 

You may be one of the millions of people around the world affected by autism. Or you might know someone personally affected by the disorder or have realized its impact on people and the world. Either way, it is encouraged that you educate yourself on what autism is and what the three types of autism spectrum disorders are. In doing so, you will have a better understanding about the disorder, which can help you to interact and communicate more effectively with individuals who are on the spectrum and to put yourself in their shoes. 

The information provided in this article can give you all the necessary tools to understand autism and its three different spectrums.

The three types of ASD that will be discussed are:

  • Autistic Disorder
  • Asperger’s Syndrome
  • Pervasive Development Disorder

What is Autism Spectrum Disorder?

Autism Spectrum DisorderAccording to the National Institute of Mental Health, autism spectrum disorder is defined as a “group of developmental disorders” that “includes a wide range of symptoms, skills, and levels of disability.” Autism can be found in around 1 in 68 people in some shape or form. Those with autism spectrum disorders have these main characteristics:

  • Repetitive or restrictive behaviors, as well as limited interests.
  • Symptoms that affect their abilities to function properly in social aspects of life.
  • Ongoing social problems that can make it difficult to communicate or interact with others.

To be more specific, they list more symptoms that are split into two categories.

Social communication / interaction behaviors may include:

  • Making little or inconsistent eye contact
  • Tending not to look at or listen to people
  • Rarely sharing enjoyment of objects or activities by pointing or showing things to others
  • Failing to, or being slow to, respond to someone calling their name or to other verbal attempts to gain attention
  • Having difficulties with the back and forth of conversation
  • Often talking at length about a favorite subject without noticing that others are not interested or without giving others a chance to respond
  • Having facial expressions, movements, and gestures that do not match what is being said
  • Having an unusual tone of voice that may sound sing-song or flat and robot-like
  • Having trouble understanding another person’s point of view or being unable to predict or understand other people’s actions

Restrictive / repetitive behaviors may include:

  • Repeating certain behaviors or having unusual behaviors. For example, repeating words or phrases, a behavior called echolalia
  • Having a lasting intense interest in certain topics, such as numbers, details, or facts
  • Having overly focused interests, such as with moving objects or parts of objects
  • Getting upset by slight changes in a routine
  • Being more or less sensitive than other people to sensory input, such as light, noise, clothing, or temperature

Symptoms can typically be observed early in life, as young as two-years old; however, many individuals are not diagnosed until the school-age years or even high school. It all depends on the severity of symptoms and having someone notice that there is an issue. 

Those who are autistic can be impaired only mildly by these symptoms, while some others may be impacted severely. Here is where the three types of spectrum disorders come into play. Each type of spectrum is defined by its varying degrees of symptoms. Next, we will outline the three types of autism spectrum disorders.

Autistic Disorder

This type of spectrum can also be known as “classic” autism. This type is usually what people think of when they hear the world “autism.” According to the Autism Support of West Shore, those with this type of spectrum disorder have “significant language delays, social and communication challenges, and unusual behaviors and interests.” These people are usually affected by intellectual disabilities as well. This type is considered the most severe form of autism and also the most common.

People who have autistic disorder may have problems with being touched by other people, perform restricted or repetitive behaviors, experience sensory overload, and may have issues communicating. Most other types of autism have the same symptoms, but this particular type means that those symptoms are much more severe.

Some people refer to ‘levels’ when speaking or writing about autism. To compare an autistic disorder to a level, you can most likely look at levels two and three on the spectrum, which are the most severe (three) and moderate (two). 

The experts at Autism Speaks discuss the three levels of autism in more detail and refer to the American Psychiatric Association’s Diagnostic and Statistical Manual for Mental Disorders (DSM-5 ). 

They consider level three as “requiring very substantial support,” level two as “requiring substantial support,” and level one as “requiring support.” As you can see, there is a continuum of severity and the level of support someone with autism will commonly need for each. 

Asperger’s Syndrome is the most mild form of autism and is closely associated with level one of ASD. 

Asperger’s Syndrome

This is one of the milder types of autism spectrum disorder. People with Asperger’s may experience the same symptoms as the other types, but they tend to be milder. Usually, people with Asperger syndrome have unusual behaviors and interests, in addition to social challenges. These symptoms tend to be the most difficult of this type of spectrum, as problems with language or intellectual disability do not tend to affect those with Asperger’s.

The autism experts at Applied Behavioral Analysis Programs list 10 common characteristics of someone who has Asperger’s Syndrome. 

  • Intellectual or artistic interest
  • Speech differences
  • Delayed motor development
  • Poor social skills
  • The development of harmful psychological problems
  • Detail-oriented
  • Persistence
  • Not socially-driven
  • High integrity
  • Masters of routine

What are some similarities between Autistic Disorder and Asperger’s?

Both those with autism and Asperger’s are known to have difficulty in social and behavioral situations, as well as forming and keeping relationships. They both also typically have a difficult time accurately reading social cues, facial expressions, and gestures. Those with autism who are higher-functioning and those with Asperger’s both fare well with academics compared to the individuals on another level of autism. 

Did you know that several celebrities have come out to the public about having Asperger’s Syndrome? Guess who?

  • Dan Aykroyd
  • Courtney Love
  • Greta Thunberg
  • Anthony Hopkins 
  • Andy Warhol
  • David Byrne
  • James Taylor
  • And surely many more! 

You probably know a few people with Asperger’s and do not even know it. Some individuals aren’t even officially diagnosed until they are older; many stumble upon a description of it and say, “Hey, that sounds just like me!” Or maybe a friend or family says something to that person and they begin to wonder. Some may choose to secure an official diagnosis with a professional, while others may not want to be “labeled.” Either way is fine! Being diagnosed with a type of ASD does not change who you are as a person inside or out. 

Pervasive Developmental Disorder

This type of autism spectrum disorder is also known as “atypical autism.” This type is typically reserved for those who meet some of the criteria for the other two types, but not all of them. Those affected with PDD-NOS (Pervasive Developmental Disorder-Not Otherwise Specified) experience milder symptoms or fewer symptoms. Quite typically, those with PDD-NOS only suffer from social and communication challenges. These people tend to be the highest-functioning autistic types and simply do not fit into any of the other categories or types of autism spectrum disorders.

Many young children are diagnosed with pervasive developmental disorder after showing mild symptoms of autism in order to continue monitoring them. It may turn out after observation periods that the child is truly categorized within a level one or two; or it might turn out that the child actually does not even have autism at all. 

The autism experts at Applied Behavioral Analysis Programs state the following: 

“Usually a person is diagnosed with Pervasive Developmental Disorder if they exhibit social and communication challenges, but simply do not exhibit other symptoms of Asperger’s, like obsessions over certain topics, developmental delays, or awkward mannerisms. People with Pervasive Developmental Disorder typically live mostly ordinary lives and are considered the highest-functioning of all autism subtypes, but can have issues relating to people, understanding language, accepting change in surroundings or routines, and dealing with their own emotions.”

Getting Diagnosed

autism spectrum disorderAs stated previously, most individuals are diagnosed with ASD as children, yet many still do not get diagnosed until later in life for various reasons. It is imperative that ASD be diagnosed early on so that interventions can begin. 

The CDC states the following and lists the steps in the process of screening and diagnosing ASD:

“Monitoring, screening, evaluating, and diagnosing children with ASD as early as possible is important to make sure children receive the services and support they need to reach their full potential.”

  • Developmental monitoring
  • Developmental screening
  • Comprehensive developmental evaluation 

For more details, review the CDC’s Fact Sheet on Developmental Monitoring and Screening. 

As an adult, there is no technical diagnostic test for ASD, but a clinician can help with the diagnostic process. If you believe you may have ASD, contact your physician to discuss what you need to do to get an official diagnosis. And if you have a feeling you do have ASD but do not want a diagnosis, that is completely okay too. Whatever you feel needs to happen for you to be happy and successful in life is what matters the most. 


This information on the three types of autism spectrum disorder can help you understand individuals with autism better. More and more information has come to light about autism in recent decades due to new research, shedding insight on the symptoms, unique characteristics, and treatment modalities of this disorder. While more research still needs to be done on treatments and interventions for those with autism, we know a vast amount more than we did in the recent past. Those with either type of autism spectrum disorder can live a full and happy life; however, some need an early diagnosis as well as ABA interventions put in place to ensure success in the critical areas of need. If you suspect a child has a type of ASD, please pass your observations along to the teacher, parent, school nurse, clinician, etc. Intervening early is the key.

ABA Programs Guide Staff

Updated January 2021