What's the Difference Between High- and Low-Functioning Autism?

People with autism are often described as being "high-functioning" or "low-functioning," but there are no such official diagnoses.

In fact, now that Asperger's syndrome, PDD-NOS, and autistic disorder have been removed from the fifth version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), there's only one general category called autism spectrum disorder (ASD).

A teacher helping her student in the classroom
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While there are now three levels of autism described in the DSM-5 (Levels 1, 2, and 3), many people still use the terms high- and low-functioning, as they're less clinical.

The problem is that the difference between high- and low-functioning autism can, in many cases, be based on the personal perspectives of a parent, practitioner, or teacher.

Problems With the Terms

Is a person high-functioning if they're verbal and bright but have severe sensory challenges and can't stay in school or hold down a job? Are they low-functioning if they can't use spoken language but are a successful visual artist?

The terms can cause miscommunication and confusion because neither one describes the level of ability or function across multiple categories.

Neither term identifies a person's:

  • Level of intelligence
  • Special talents
  • Anxiety
  • Perseveration
  • Aggression
  • Sensory challenges

Neither term provides useful information about where they'd do best in school, because intelligence, noise tolerance, anxiety, and social communication all must be considered.

Neither term gives you useful information about whether they can function successfully in a public venue. Someone who's "low-functioning" may be able to sit and enjoy a movie, while someone described as "high-functioning" may not be able to manage the sensory challenges.

Neither term tells you whether they're likely to do well in a job. Some people with "low-functioning" autism are happily and gainfully employed, while quite a few people with "high-functioning" autism can't find and keep a job they like.

Perhaps most significantly, neither term identifies the likelihood of aggressive behavior. While relatively rare, aggression occurs in autistic people at all levels of severity. Even people with very high-functioning autism, who have strong language skills, can "melt down" under certain circumstances.

Autistic vs. Neurotypical

Despite problems inherent in the terms high- and low-functioning autism, they are in common use, usually by people who are not autistic. They're often used to describe the degree to which someone on the autism spectrum is (or appears to be) similar to neurotypical people.

In other words, autistic people who are or appear to be closer to "normal" are considered to be high-functioning. For example, many people define a high-functioning person with autism as:

  • Having the ability to communicate using spoken language
  • Being able to manage the expectations of an academic setting, which often is a result of using spoken language and having a greater awareness of other people's expectations
  • More likely to be included, with or without support, in general classrooms and extracurricular programs
  • More aware of social conventions, such as using utensils properly and greeting people appropriately
  • More likely to appear typical (until some event or conversation makes their autism more obvious)

They tend to identify someone with low-functioning autism as:

  • Having limited or no spoken language and using technology or picture boards to communicate
  • Looking and sounding different from their neurotypical peers so that their autism is more obvious to the casual observer
  • Less likely to be included in typical classes or activities and more likely to be in a "substantially separate" academic setting 

All of these distinctions, however, are artificial, and they're by no means absolute. That's because people with autism behave differently in different situations, and every individual has a range of strengths and challenges.

It's handy but not useful to describe people with autism compared to neurotypical people because of varying levels of "typical" behavior in different situations. Someone who appears exceptional in a college classroom may be unable to function at a party. Meanwhile, someone who's non-verbal in person may be able to converse well online.

Levels of Autism

To provide some type of differentiation in diagnosis, the DSM-5 now includes three levels of autism based on necessary levels of support. People with Level 1 autism need the least support, while people with Level 3 autism need the most.

While this diagnostic approach sounds logical, it has not proved to be particularly useful. That's in part because the need for support varies for so many reasons.

For example, the same child may need minimal support in the home, significant support at school, and a great deal of support in a new, unstructured social situation. 

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