What is "High Functioning Autism," and Why Is It So Hard to Define?

Terms Like "High Functioning Autism" Can Be Confusing

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Why Is It So Hard to Define "High Functioning Autism?"

In a very general way, "high functioning autism" means "a person with relatively mild symptoms which, despite their mildness, are significant enough to merit an autism spectrum diagnosis." 

But there is no formal diagnosis called "high-functioning autism," and no agreed upon definition of "high functioning."  Add to this the fact that many people with autism may be bright, accomplished, and yet have severe symptoms (such as anxiety and sensory dysfunction) that significantly impact their daily functioning.

  As you can see, the term is hard  to pin down.

And, as of 2013, it's become even harder to define "high functioning autism."  Here's why:

Until 2013, many people who might be said to have high functioning autism were diagnosed with either Asperger syndrome or PDD-NOS (Pervasive Developmental Disorder Not Otherwise Specified)

  • Asperger syndrome was a distinct diagnosis which described a person of average or higher-than-average intelligence and age appropriate language skills who also had significant social and communication challenges.
  • PDD-NOS was a catch-all diagnosis. Often understood to mean the same thing as "high functioning autistic," it really incorporated individuals at all function levels whose symptoms don't fully correlate with classic autism.

As of 2013, with the publication of the DSM-5, neither PDD-NOS nor Asperger syndrome are official diagnostic categories in the United States.


Why "Level 1" Autism Isn't the Same as "High Functioning Autism"

With the DSM-5, instead of separate diagnoses, there is just one big group of people diagnosed with Autism Spectrum Disorder.  But people with autism are still very different from one another.  So, to clarify these differences, the DSM-5 also includes functional levels.

People who are overall quite functional (and thus, theoretically at least, in need of less support) are generally given the diagnosis of Level 1 Autism Spectrum Disorder.

But what does a person with Level 1 Autism Spectrum Disorder look like? The answer is as diverse as the people who have the diagnosis.  For example:

  • They can use age-appropriate language, read, write, do math, show affection, complete daily tasks--but can't hold eye contact, maintain a conversation, engage in play,or  pick up on social cues.  OR...
  • They have significant speech and language delays but are able to take part in an inclusive academic program because their age-appropriate academic skills.  OR...
  • They have relatively mild speech and social delays but have severe sensory issues which make it impossible for them to take part in an inclusive academic program.  OR...
  • They have severe anxiety, learning disabilities, and sensory challenges -- but have age-appropriate speech and extraordinary abilities in music, math, and engineering.  OR...

    In short, the possible combinations of strengths and challenges are almost endless. This means that the concept of "Level 1" autism is also pretty tricky.  Apparently, the people who developed the idea of "Levels of Support" were thinking in a very general way -- that is, people with Level 3 autism need 24/7 skilled support, while people with Level 1 autism...  don't. 

    How Much Support Does a "High Functioning" Individual Need?

    While few people with "high functioning" autism need help with toileting or basic hygiene, they may very well need a good deal of support in other settings.  For example, a very bright individual with severe sensory issues, anxiety, and perseveration might actually have a MORE difficult time in the workplace than a less intelligent individual with less anxiety and fewer sensory issues.

    What's more, a "lower functioning" individual might spend most of their day in a supported setting where the possibility of dangerous interactions is almost zero. Meanwhile, the individual with "high functioning" autism may need to navigate a world of complex and hazardous situations. Who needs more support under those circumstances?

    If this leaves you feeling that the definition of high functioning autism is clear as mud, you're not alone! At least now, however, you understand why the term is so tough to nail down -- and you know you're in good company.


    Attwood, Tony. The Complete Guide to Asperger Syndrome. Jessica Kingsley Press:2007.

    Koyama T, Tachimori H, Osada H, Takeda T, Kurita H. "Cognitive and symptom profiles in Asperger's syndrome and high-functioning autism." Psychiatry Clin Neurosci. 2007 Feb;61(1):99-104.

    Seung HK. "Linguistic characteristics of individuals with high functioning autism and Asperger syndrome." Clin Linguist Phon. 2007 Apr;21(4):247-59.

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