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

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People with autism are often described as being "high functioning" or "low functioning." But there are no such diagnoses in the diagnostic manual.

In 2013, new diagnostic criteria for autism were created to describe three levels of autism. These levels are supposed to describe the level of support each individual requires.  But there is nothing in the criteria that describes which strengths or challenges would slot an individual into a particular level.

And of course the level of support required by any individual varies based on the situation and setting.

So what is meant by these terms?

The answer isn't obvious.

  • Neither term necessarily describes Intelligence, special talents, anxiety level, or level of sensory challenges.
  • Neither term gives you really useful information about whether a person can function successfully in a public venue.  There are people with "low functioning" autism who can sit through and enjoy a movie, for example -- and there are people with "high functioning" autism who find the crowds, smells, sounds, and other sensory challenges to be impossible to manage.
  • Neither term tells you whether a person is likely to do well in a job.  There are  people with "low functioning" autism who are happily and gainfully employed, and quite a few people with "high functioning" autism who are not able to find and keep a job they like.
  • Perhaps most significantly, aggressive behavior, while relatively rare, 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.

So why and when are the terms used?

In general, the terms are used by people who are not autistic.

  And they are used to describe the degree to which someone on the spectrum is (or appears to be) similar to people who are NOT on the spectrum.  In other words, autistic people who are or appear to be closer to "normal" are considered to be high functioning. Thus, for example:

  • High functioning people use spoken language to communicate.  Low functioning people are more likely to use technology or picture boards, and may have limited or no spoken language.
  • High functioning people are more likely to be able to manage the expectations of an academic setting. This is often a result of having a better handle on spoken language, and a greater awareness of the expectations of others.
  • High functioning people are usually more aware of social conventions. For example, they are more likely to use tools and utensils typically, greet others appropriately, etc. 
  • Low functioning people generally look and sound very different from their typical peers. In other words, their disability is more visually and aurally obvious to the casual observer. High functioning people are more likely to appear typical (until some event or conversation makes their autism more obvious).
  • Low functioning people are less likely to be included in typical classes or activities, and are more likely to be in a "substantially separate" academic settings.  High functioning people are more likely to be included -- with or without support -- in general classrooms and out-of-school programs.

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

As a result, low functioning people may be successful where high functioning people are not -- and vice versa.  For example, the "high functioning" person who appears  "normal" (or even exceptional) in a college classroom may find it impossible to function at a party. Meanwhile, the "low functioning" person who can't use spoken language to chat may be more than capable of leading a conversation online.

It's very unlikely that the terms "high functioning" and "low functioning" will disappear anytime soon. It's important, therefore, to understand their significance (and lack of significance) when it comes to labels, services, and expectations.

The ability to use spoken language is not a sign of intelligence.  The ability to function well in a classroom is not a guarantee of strong social skills. The bottom line, therefore, is to hold the bar as high as possible for every individual and -- to borrow a phrase -- to assume intelligence.

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