Autism spectrum disorder is the diagnostic label given to a broad category of neurodevelopmental disorders.
These types used to be diagnosed individually by differences and intensity of symptoms:
- autistic disorder
- Asperger’s syndrome
- pervasive developmental disorder not otherwise specified (PDD-NOS)
In 2013, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) revised these classifications. All types of autism are now merged into a single diagnosis of autism spectrum disorder (ASD).
Changes in terminology reflect the newer diagnosis. But the previous terminology isn’t completely phased out in conversation.
Some medical professionals, parents, or autistic people themselves may use terms, like Asperger’s or PDD, but they’re no longer an official diagnosis in the U.S. classification system.
Let’s take a closer look at some terms you might hear in relation to autism and how they fit into the changing landscape.
The most obvious symptoms tend to involve communication and interaction with others.
Autistic people may have different ways of learning, thinking, and problem-solving. Intellectually, autistic people can fall on a range from severely challenged to gifted.
Everybody is different. Some people will have many symptoms, and some will have only a few. Signs of autism in a 3-year-old or 4-year-old may look different from those who are teens or adults. Some autistic people may be able to “mask” (or hide) their symptoms.
General signs of autism may include:
- not responding to their name
- avoiding eye contact or not showing an awareness when others are speaking
- not understanding sharing or taking turns
- not looking at objects shown to them
- not pointing or responding to pointing
- having difficulty understanding facial expressions
- repeating words or phrases
- performing repetitive movements (stimming)
- having difficulty expressing needs
- preferring solo play, or having an inability to play “pretend” games
- having difficulty adapting to change or having emotional meltdowns
- showing hypersensitivity to sound, smell, taste, sight, or touch
- needing to organize the physical environment
- having delayed speech and language skills, or lack of gesturing
- losing previously learned skills
In older children and adults, you might also notice:
- having difficulty reading body language, facial expressions, and other social cues
- not getting sarcasm, teasing, or figures of speech
- speaking in monotone
- having difficulty forming relationships
When autism was categorized by types, the lines between the different types of autism could be blurry. Diagnosis was, and still is, complicated and often stressful for families.
If you or your child received a diagnosis before the DSM-5 changed, you may still be using the older terminology (i.e. Asperger’s). That’s OK. Your doctor may continue to use those terms if they help.
Asperger’s syndrome was on the mild end of the spectrum. People with Asperger’s were often considered “high functioning,” with average-to-above-average intelligence and without speech delays. Some autistic people object to the terms “high functioning” or “low functioning.”
Signs and symptoms included:
- having impairment in social interaction
- trouble reading facial expressions, body language, and social cues
- not understanding irony, metaphor, or humor
- showing awkward body language, standing too close, or talking too loudly
- lacking eye contact
- repeating the same behaviors and activities
Note that all these symptoms above and below can also apply to ASD. The main difference between Asperger’s syndrome and autism is the less severe symptoms and the lack of language delays in Asperger’s syndrome.
Children who were given an Asperger’s label may have more subtle differences, and they frequently have strong language and cognitive skills.
To others, these can be interpreted as signs of rudeness, so forming friendships can be challenging. Other signs included:
- poor handwriting
- narrow range of interests or preoccupation with a single interest
- repetitive behaviors
- need for routine and rigid rules
- easily upset when things don’t go as planned
Pervasive developmental disorder not otherwise specified (PDD-NOS)
The diagnosis of PDD-NOS was given when a developmental disorder didn’t quite meet the criteria for autism, Asperger’s syndrome, Rett syndrome, or childhood disintegrative disorder.
PDD-NOS was also called “atypical autism.”
Signs of PDD-NOS included:
- deficits in social behavior
- uneven skill development
- poorly developed speech and language
- difficulty accepting change
- uncommon responses to taste, sight, sound, smell, or touch
- repetitive or ritualistic behaviors
- highly restricted and focused interests
These symptoms can apply to ASD now.
Autistic disorder was considered on the more severe end of the spectrum. You’d likely see more noticeable symptoms early on. These involve:
- challenges with social interaction
- communication problems
- repetitive behaviors
Other signs included:
- tantrums or “meltdowns“
- sleeping and eating disturbances
Children who were on the severe end of the spectrum may have preferred playing alone and had difficulty interacting with peers. A high level of support was needed for them.
Childhood disintegrative disorder
A child with this disorder met normal developmental milestones for the first few years. After that, there was a rapid decline in acquired skills involving:
- language and communication
- social skills, play, and self-care skills
- motor skills, and bowel and bladder control
Childhood disintegrative disorder fell on the severe end of the spectrum.
The spectrum illustrates a broad range of developmental delays and symptom severity.
ASD includes people who have a few mild autistic traits to those who need help with day-to-day functioning. It represents every intelligence level, as well as varying degrees of communication and social abilities.
The differences between one type and another type can be subtle and difficult to determine.
Terms like “mild” or “high functioning” aren’t official diagnoses. Some people find these terms useful, but many in the autistic community haven’t found them to be helpful or accurate, largely due to the range of abilities that can be present in an autistic person.
You may also have heard about three “levels” of autism, with level 1 being the mildest and level 3 the most severe.
High functioning autism
High functioning autism describes “mild” autism, or “level 1” on the spectrum.
Asperger’s syndrome is often described as high functioning autism. Symptoms are present, but the need for support is minimal.
Broad autism phenotype
Broad autism phenotype is a term that’s rarely used.
It’s usually described as “autistic traits” without a diagnosis. Symptoms are mild and not clinically significant for diagnosis.
Researchers have noted that this is sometimes seen in relatives of people with an autism diagnosis.
Severe autism is sometimes called “level 3” on the spectrum. People with severe autism require help with day-to-day functioning.
Caregiving, or a high level of support, may be needed across the lifespan.
Rett syndrome or Rett disorder has also been called “autism-dementia-ataxia-loss of purposeful hand use syndrome.”
But it’s not included on the autism spectrum. It’s a brain disorder caused by genetic mutations.
Classic Rett syndrome usually affects girls who display typical development for the first few months. Then, symptoms start to appear, involving issues with:
- language and communication
Eventually, affected children may have repetitive hand movements. Other symptoms include:
- slowed growth or small head size
- spitting and drooling
- uncommon eye movements, staring, or blinking
- cold extremities
- sleep disturbances
- breathing abnormalities
- curvature of the spine
If you think your child might have symptoms of autism, speak with their pediatrician or a primary care physician. They can refer you to the appropriate specialist, such as a:
- developmental pediatrician
- child neurologist
- psychiatrist or psychologist
You can also request an evaluation from your state’s public early childhood assistance center. It’s free, and you don’t need a doctor’s referral or diagnosis. Your local public school district can also provide assistance.
There’s no one medical test to diagnose autism spectrum disorder. A doctor can make the diagnosis with a comprehensive behavior evaluation and developmental screening.
Some people on the spectrum need minimal support services. Others require a lot. Either way, early intervention is associated with long-term positive effects.
The diagnosis of autism spectrum disorder includes a number of conditions that were diagnosed separately prior to 2013. The lines between those conditions weren’t always clear and could be confusing for everyone involved.
The spectrum covers a wide range of symptoms and severity. The evolution to the spectrum and the changing terminology should help make things easier to understand.
No matter the differences across the spectrum, autistic people can learn skills that can last a lifetime.