Different Levels of Autism

There are different types of autism

When you receive a diagnosis of an autism spectrum disorder (ASD), it often comes with a functioning level attached. It can be overwhelming to sort through these terms to figure out what they mean in a practical sense. Understanding how psychologists and other medical professionals assign different levels of autism can help you comprehend the real meaning of an autism diagnosis.

Types of Autism and Functioning Levels

Autism Subtype Mild ASD Moderate ASD Severe ASD
Asperger's Yes No No
Classic autism Yes Yes Yes
PDD-NOS Yes Yes No
Rett's syndrome No Yes Yes
Childhood disintegrative disorder No Yes Yes

Typically, when you or your child receives an autism diagnosis, it will involve one of the five autism subgroups. According to WebMD, the subgroups are as follows:

  • Asperger's syndrome - This diagnosis indicates an individual with a high functioning level and good verbal skills. Most of the impairment is in social interactions and functional use of language. Many health professionals are hesitant to diagnose people with Asperger's because it's likely that this disorder may be considered high-functioning autism in future versions of the Diagnostic and Statistical Manual (DSM).
  • Autistic disorder - If the individual meets the basic criteria for autism diagnosis laid out by the DSM-IV, they will receive this medical label. Functioning can range from very high to very low.
  • Pervasive developmental disorder, not otherwise specified (PDD-NOS) - Individuals receive this diagnosis if they have some but not all of the characteristics of classic autism. Their functioning level is usually moderate to high.
  • Rett's syndrome - Individuals with this disorder are usually female and can have moderate or low functioning levels. The disorder develops as the child ages.
  • Childhood disintegrative disorder - This disorder typically affects toddlers and preschoolers. They lose language and social skills and typically have moderate or low functioning levels.

How Functioning Level Is Determined

Most practitioners describe autism as a spectrum. At one end of the spectrum are those who cannot function in society due to their impairments, while at the other end are those "quirky" people who can lead independent and successful lives. According to Autism Europe, the functioning level of an individual describes where he or she falls on this spectrum.

Psychologists and medical professionals use standardized tests to diagnose autism, and they also use tests to determine the severity of the disorder. One such test, the Childhood Autism Rating Scale (CARS), asks the person assessing the individual to rank the autistic symptoms on a scale of 1 to 4, with 4 being the most severe. If the individual receives a higher score on the CARS assessment, he or she is diagnosed with severe autism. Conversely, if the person with autism receives a lower score, he or she is diagnosed with high-functioning or mild autism.

Characteristics of Low-Functioning or Severe Autism

Individuals with a low level of functioning are commonly diagnosed with classic autism, childhood disintegrative disorder, or Rett's syndrome. Those with severe autism may not be able to live independently as adults. The characteristics in children and adults with low-functioning autism are similar and may include the following.

Impaired Mental or Cognitive Functioning

According to the National Institute of Mental Health, some individuals with autism, especially those with low functioning levels, also have a degree of mental retardation. This usually includes an IQ of below 70 and problems with adaptive behaviors like self-care and communication.

Girl using sensory station
Girl Using Sensory Station

Lack of Language

Autism Speaks reports that 25% of people on the spectrum are non-verbal. This means they cannot use spoken words to communicate with others. Many people diagnosed as low-functioning are non-verbal. Those that are verbal have great difficulty using words to communicate.

Severe Behavior Concerns

Repetitive or atypical behaviors are a hallmark of autism, and in those with low-functioning autism, these behaviors may severely affect day-to-day activities. Additionally, frustration about communication and sensory overload can lead to behaviors that disrupt others and may even cause harm to the individual. If forced to deal with a change in routine, an individual may become very angry.

Socially Unreachable

It is very difficult to interact with someone with severe autism. The individual may not be aware of what others are saying or doing, and it may take significant effort to gain his or her attention.

Characteristics of Moderate Autism

Those who have moderate autistic disorders may carry a diagnosis of classic autism, childhood disintegrative disorder, Rett's syndrome, or PDD-NOS. Adults with moderate autism often require assistance, but they can have some level of independence in their jobs and living conditions. Both children and adults with moderate autism spectrum disorders may exhibit the following characteristics.

Normal or Below-Normal Mental Functioning

A person with moderate autism may have some degree of mental retardation, or he or she may have a normal IQ of about 100. This person may find self-care tasks challenging.

Difficulty Communicating

Someone with moderate autism is likely to have trouble communicating. While he or she may be verbal, it may be very challenging to converse in a typical manner. Speech may include some functional communication and some repetitive language or non-functional verbal attempts. The individual may prefer to communicate through signs or technological devices.

Some Behavior Concerns

Mother helps her autistic son with schoolwork.
Mother helps her autistic son with schoolwork.

An adult or child with moderate autism may be over or under-sensitive to sounds, sights, and other types of stimulation. This may lead to behavior concerns. Additionally, it's common for those with moderate autism to actively resist any change in their normal routine and to display behaviors like rocking, hand flapping, walking on toes, or spinning in circles.

Socially Aloof

A person with a moderate autism spectrum disorder will appear aloof. He or she may not try to interact with others, and it may be very challenging to initiate an interaction with this person. However, someone with moderate autism is generally aware that others are in the room.

Characteristics of High-Functioning or Mild Autism

Children and adults with high-functioning autistic disorders may be diagnosed with Asperger's disorder, classic high-functioning autism, and PDD-NOS. Many high-functioning autistic individuals live and work independently. High-functioning autism has the following characteristics:

Normal or Above-Normal Intelligence

People with mild autistic spectrum disorders have normal intelligence, and in many cases, they score well above normal on IQ tests. Despite this, they may struggle with some tasks requiring them to make sudden decisions or change regular routines.

Normal Verbal Skills But Some Communication Challenges

In order to be diagnosed with high-functioning autism, an individual must be verbal. He or she may struggle with functional communication, however. This type of individual may know several different synonyms for the word "beverage," but he or she may find it challenging to ask for a drink in some situations. Tone of voice may also appear robotic or odd.

Fewer Behavior Concerns

While an individual with high-functioning autism may show some resistance to routine and some repetitive motions, he or she is unlikely to disrupt others significantly with these behaviors. This person may have a passionate interest in a single topic. There may be some sensory concerns as well.

Socially Atypical

Someone with mild autism may struggle with the finer points of social interaction, including eye contact, maintaining a back-and-forth conversation, interpreting body language and tone of voice, and interacting with others at an age-appropriate level. This person may have difficulties taking the perspective of others.

Can Functioning Levels Change?

It's important to remember that the functioning level of an individual on the spectrum can change dramatically with the right therapies and treatments. The journal Pediatrics published a study reporting that one early intervention model improved children's IQs by an average of 17.6 points. Additionally, early intervention, especially before the age of three years, can improve adaptive behaviors, social functioning, language usage, and behavior issues. These practical improvements often result in an official improvement in the individual's functioning level.

Don't Get Caught Up in the Diagnosis

Whether you or your child has been diagnosed with an autism spectrum disorder, it's important to remember not to get too caught up in the diagnosis. Although there are several different levels of autism, where a person falls on this spectrum can change significantly over the course of a lifetime. The person's functioning level is only a statement about how he or she is performing at this moment in time.

Different Levels of Autism