Understanding the Three Levels of Autism

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Anyone who meets the criteria for having autism spectrum disorder (ASD) will be further diagnosed as having ASD level 1, ASD level 2, or ASD level 3, according to criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5).

These levels are based on a person's strengths and limitations in regards to their ability to communicate, adapt to new situations, expand beyond restricted interests, and manage daily life. They specifically indicate how much support an autistic person needs, with level 1 meaning relatively little support is required and level 3 indicating the need for a great deal of support.

3 functional levels of autism
Illustration by Cindy Chung, Verywell

The three levels of autism make it possible for doctors to make a specific diagnosis and also helps anyone who's caring for someone with autism to have a clear understanding of that person's strengths and limitations. The levels reflect a more refined way of diagnosing autism than did the previous DSM.

In the DSM-IV, autism was divided into five distinct diagnoses ranging from Asperger's syndrome (essentially a synonym for mild or "high-functioning autism") to autistic disorder, which indicated severe autism.

Level 1: Requiring Support

Level 1 ASD is the mildest, or the most "high-functioning," form of autism. Children with level 1 ASD have a hard time communicating appropriately with others. For example, they may not say the right thing at the right time or be able to read social cues and body language.

A person with ASD level 1 usually is able to speak in full sentences and communicate, but has trouble engaging in back-and-forth conversation with others. They may try to make friends, but not be very successful.

They may also be inflexible in certain ways and have trouble moving from one activity to another. Additionally, they may have problems with organization and planning that prevent them from being independent.

Level 2: Requiring Substantial Support

People with ASD level 2 will have more obvious problems with verbal and social communication than those diagnosed with level 1. Likewise, they will find it harder to change focus. They might, for example, get very upset when they have to move from one activity to the next or to leave school at the end of the day.

Children with level 2 tend to have very narrow interests and engage in repetitive behaviors that can make it difficult for them to function in certain situations. 

A person diagnosed with ASD level 2 tends to speak in simple sentences and also struggles with nonverbal forms of communication.

Level 3: Requiring Very Substantial Support

Level 3 is the most severe form of autism. Children in this category will manifest many of the same behaviors as those with levels 1 and 2, but to a more extreme degree. Problems expressing themselves both verbally and nonverbally can make it very hard to function, interact socially, and deal with a change in focus or location.  Engaging in repetitive behaviors is another symptom of level 3 ASD.

A person with ASD level 3 will have a very limited ability to speak intelligibly and will rarely initiate interactions. When they do initiate an interaction, they will do so awkwardly. Someone with level 3 will also respond only to very direct social approaches from tother people.

Limitations of ASD Levels

Although the ASD levels of support are useful for indicating where an autistic person falls on the spectrum regarding severity, they have significant limitations. They can be subjective and lacking in nuance, and the DSM-5 offers little specificity regarding the types of support indicated or situations in which support is needed—for example, some autistic people need support at school but are fine at home, while others may do well at school but struggle in social situations.

What's more, the level a person is assigned when they're first diagnosed can shift as they develop and refine social skills and as the severity of issues such as anxiety or depression, common among people with autism, decreases.

The bottom line: Being assigned one of the three levels of autism can be useful for understanding how high- or low-functioning someone is likely to be and determining what types of services and supports would serve them best. It won't, however, predict or account for nuances in their personality and behavior, which means the support and services they receive will need to be highly individualized.

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  1. Autism Speaks. Autism Diagnosis Criteria: DSM-5.

  2. Weitlauf AS, Gotham KO, Vehorn AC, et al. Brief report: DSM-5 "levels of support:" A comment on discrepant conceptualizations of severity in ASD. J Autism Dev Disord. 2014;44(2):471-6. doi:10.1007/s10803-013-1882-z

  3. Masi A, Demayo MM, Glozier N, et al. An overview of autism spectrum disorder, heterogeneity and treatment options. Neurosci Bull. 2017;33(2):183-193. doi:10.1007/s12264-017-0100-y

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