In the past, doctors diagnosed autism according to four different subtypes of the condition. However, healthcare professionals now classify autism spectrum disorder as one broad category with three different levels to specify the degree of support an autistic person needs.

Before 2013, healthcare professionals defined the four types of autism as:

However, the American Psychiatric Association revised their Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013, which did not include these four subtypes of autism. They now all fall under the one umbrella term of ASD.

Keep reading to learn more about how we categorize ASD, including the various levels, and how doctors diagnose the condition.

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ASD is now the umbrella term for the group of complex neurodevelopmental disorders that make up autism. It is a condition that affects communication and behavior.

The autism spectrum refers to the variety of potential differences, skills, and levels of ability that are present in autistic people.

According to the Centers for Disease Control and Prevention (CDC), around 1 in 54 children in the United States are on the autism spectrum.

The differences in autistic people are often present from early childhood and can impact daily functioning.

Autistic people can experience the following challenges:

  • having trouble communicating and interacting with others
  • exhibiting repetitive behaviors
  • having difficulty functioning in several areas of their life

Differences in people with ASD generally appear in the first 2 years of life. It is also three to four times more common in boys than in girls, although some research indicates this could be due to bias, as some autistic girls may go undiagnosed.

The DSM–5 lists the two main symptom categories of ASD as a persistent deficit in social communication, interaction, or both, along with restricted, repetitive patterns of behavior.

According to the National Institute of Mental Health, early signs of ASD can include:

  • little or inconsistent eye contact
  • not sharing enjoyment of objects or activities by pointing or showing things to others
  • difficulty responding to adult attempts to gain attention
  • difficulty with back and forth communication
  • talking at length without gauging the interest of others
  • a flat tone of voice
  • difficulty with perspective-taking
  • sensory sensitivities
  • repeating certain behaviors, words, or phrases
  • intense interests in specific things
  • becoming upset by changes in routine
  • problems sleeping

While autistic people may face many challenges, they may also have differences that many would consider strengths. These include:

  • superior memory for facts and figures
  • specialist knowledge in topics of interest
  • high level of motivation and enthusiasm in activities of interest, with a drive to share this enjoyment and enthusiasm with others
  • a high degree of accuracy in various tasks
  • innovative approaches to problem solving
  • exceptional attention to detail
  • ability to follow instructions accurately, under appropriate guidance
  • exceptional skills in creative skills
  • ability to see the world from an alternative perspective and therefore offer unique insights
  • a tendency to be nonjudgmental, honest, and loyal in social relationships
  • a unique sense of humor

Medical professionals can carry out screening for autism in the first few years of a child’s life.

Doctors diagnose ASD by assessing the differences and signs listed above, interacting with the child or observing interactions between the child and parent or caregiver, and asking parents and caregivers questions.

There were previously four different types of autism. However, the DSM–5 now lists three different levels of ASD, which doctors determine according to the amount of support an individual requires.

However, it is important to note that many mental health professionals do not find these levels helpful, instead preferring to diagnose people with autism based on the spectrum as a whole rather than classifying them using levels.

The three levels of ASD are:

Level 1: Requiring support

The communication issues that a person with Level 1 ASD may face include:

  • difficulty initiating social interactions
  • atypical or unsuccessful response to social interaction from others
  • decreased interest in social interactions in some cases
  • the ability to speak in clear sentences and engage in communication, but with an issue maintaining a two-way conversation with others
  • difficulty making friends

The repetitive behavioral issues a person with Level 1 ASD may face include:

  • inflexible behavior that interferes with general functioning in one or more contexts
  • problems switching between activities
  • issues with organization and planning, which can impact independence

Level 2: Requiring substantial support

The communication issues that a person with Level 2 ASD may face include:

  • noticeable issues with verbal and nonverbal social communication skills
  • social issues being apparent despite supports in place
  • limited initiation of social interaction
  • reduced response to social interactions from others
  • interactions that are limited to narrow special interests
  • more significant differences in nonverbal communication

The repetitive behavioral issues a person with Level 2 ASD may face include:

  • inflexible behavior
  • struggling to cope with change
  • restricted or repetitive behaviors that are obvious to a casual observer and interfere with functioning in several contexts
  • difficulty changing focus or action

Level 3: Requiring very substantial support

The communication issues a person with Level 3 ASD may face include:

  • severe issues in both verbal and nonverbal social communication, which severely impair functioning
  • very limited initiation of social interactions
  • minimal response to social interaction from others
  • using few words of intelligible speech
  • unusual methods of meeting social needs and responding to only very direct approaches

The repetitive behavioral issues a person with Level 3 ASD may face include:

  • inflexible behavior
  • extreme difficulty coping with change
  • restricted or repetitive behaviors that significantly interfere with functioning in all areas of life
  • experiencing great distress or difficulty when changing focus or action

Learn more about the levels of autism here.

The levels of ASD correspond to the severity of the autism symptoms described above and the degree of support required.

In addition, it is important to keep in mind that the amount of support an autistic person needs can vary according to different ages or situations.

Numerous therapies and behavioral interventions can help improve the specific challenges that autistic people face.

Healthcare professionals often recommend that ASD therapies begin as soon as possible after a child receives their diagnosis. Early intervention can reduce their difficulties, allowing them to adapt and learn new skills.

Management strategies for ASD may include:

  • educational and developmental therapy
  • behavioral therapy to help learn life skills and overcome other challenges
  • speech, language, and occupational therapy to help with social, communication, and language skills
  • medication to tackle accompanying mental health issues, such as irritability, aggression, repetitive behavior, hyperactivity, attention issues, anxiety, and depression
  • psychotherapy to help a person increase or build upon their strengths
  • supplements or changes in diet

It is important to note that ASD is a spectrum disorder, meaning people can experience a varying range of these differences. After an ASD diagnosis, many children go on to live productive, independent, and fulfilling lives.

ASD is a developmental disorder. It is now the umbrella term that includes all of the four former types of autism. These former types are ASD, Asperger’s syndrome, childhood disintegrative disorder, and pervasive developmental disorder-not otherwise specified.

ASD is a spectrum disorder that doctors diagnose in levels, depending on how many of the differences are present in individuals.

While people on the severe end of the spectrum may require help and assistance to function and manage their lives, with the right treatment, many autistic people can live productive, independent, and fulfilling lives.