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

Low-functioning autism and high-functioning autism are outdated terms for what are now considered different levels of autism spectrum disorder (ASD).

Autism is a developmental disability of variable severity that affects social interaction and communication. Autistic people tend to have restricted or repetitive patterns of thought and behavior. It is not an illness but a type of neurodivergence.

Rather than using functioning labels, the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) uses three levels of autism to diagnose the severity of impairment. The levels are:

• Level 1 ASD, formerly known as high-functioning autism, is the mildest form. People with level 1 autism require support.
• Level 2 ASD is the middle level of autism. People with level 2 autism require substantial support.
• Level 3 ASD, formerly known as low-functioning autism, is the most severe form of autims. People with level 3 autism require very substantial support.

This article discusses the differences between high- and low-functioning autism. It also explains why autism functioning labels are problematic in the autistic community.

What Is Low-Functioning Autism?

People with level 3 or low-functioning autism have severe deficits in social communication, extreme difficulty coping with change, and other restrictive behaviors that cause severe impairments in functioning.

While every autistic person is different, people with level 3 autism may be mute or have few words of intelligible speech. They rarely initiate social interactions and may have minimal response to social overtures from others.

These challenges make it very hard for people with level 3 autism to complete day-to-day tasks, like taking care of themselves or working.

What Is High-Functioning Autism?

People with level 1 or high-functioning autism are often able to function far more independently than those with more severe autism. They too have challenges with social communication, but typically have strong language skills. They tend to be rigid or inflexible and have difficulty with transitioning between activities.

While people with level 1 ASD are often considered high-functioning, difficulties with social communication and restrictive or repetitive behaviors can cause significant interference in day-to-day functioning.

By definition, people with level 1 ASD still require support. Without supports in place, people with level 1 autism can have noticeable impairments and problems with organization and planning can hamper their ability to be self-sufficient. 

Problems With Autistic Functioning Labels

Autistic functioning labels are often used as short-hand to describe how severely a person is impacted by ASD. However, these terms can be very misleading, and people in the autistic community feel they are harmful.

For example, a person who is labeled high functioning may be verbal and bright, but have severe sensory challenges and can't stay in school or hold down a job. A person who is considered low functioning may not be able to use spoken language but may be a successful visual artist.

Functioning labels can cause miscommunication and confusion because neither one describes the level of ability or function across multiple categories. Functioning labels do not determine a person's:

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

Functioning labels do not provide 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.

Functioning labels also do not determine whether a person is 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.

In addition, 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 "meltdown" 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)

People 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 autistic people behave differently in different situations, and every individual has a range of strengths and challenges.

Summary

The terms high-functioning and low-functioning autism are outdated phrases that can be misleading. Instead of using functioning labels, the DSM-5 now includes three levels of autism based on necessary levels of support.

People with level 1 autism are typically considered higher functioning and need the least support. People with level 3 autism are typically considered lower functioning and need the most support.

However, regardless of the level of autism, the person's need for support can vary for many reasons and may be inconsistent from one day to the next. 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. 

Functioning labels often lead to people discounting the abilities of people with level 3 autism and overlooking the need for support for people with level 1 autism.

Perhaps the most important reason to not functioning labels is actually autistic adults say these labels are misleading and harmful and increase the stigma and misperceptions of autism.