The 4 Types of Autism Spectrum Disorder Explained (2026): A Minneapolis Guide

What was the story? Up until 2013, clinicians diagnosed patients using 4 different disorders: Autistic Disorder, Asperger’s Syndrome, Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS), and Childhood Disintegrative Disorder. Each had its own set of diagnostic criteria and it caused a lot of confusion for individuals and their families looking for support.

For one thing, clinicians would sometimes reach different diagnoses for the same patient. For example, an adult in Minneapolis who was diagnosed as a child in the late 1990s or early 2000s was sometimes diagnosed as having Asperger’s Disorder by one clinician, PDD-NOS by another, and Childhood Disintegrative Disorder by a third. Clinicians at the time didn’t fully agree with the differences and distinctions between the disorders, making them hard to pin down and easy to misinterpret.

What The Data Showed
In the first years of the 2010s, researchers started noting that the 4 types were not separate disorders. The American Psychiatric Association reviewed data to update their manual prior to releasing the DSM-5 in 2013. The 4 different disorders were instead 4 presentations of Autism Spectrum Disorder.

An individual diagnosed with Asperger’s Syndrome in 2005 didn’t have a different brain from someone diagnosed as having Autistic Disorder. The differences were differences of degree, not kind. So all 4 conditions were combined into a single diagnosis: Autism Spectrum Disorder.

What The Change Meant For Parents
What did that look like for clinicians and families? It looked like:

• One diagnosis replaced the other 3, which overlapped at the time
• Clinicians began to describe the level of support an individual would require using levels of support (1, 2 or 3)
• The 2013 criteria were much more descriptive of the characteristics that individuals would need to exhibit in order to be diagnosed, particularly in the area of social communication and restrictive or repetitive behaviors
• Those previously diagnosed with PDD-NOS might not qualify as having ASD under the 2013 criteria

That last item was a concern for many families in Minneapolis. A child who had previously been diagnosed with PDD-NOS might not have automatically been diagnosed with ASD under the new criteria. This meant a loss of services for some families in the interim, particularly through school systems and medical insurance.

Why People Still Use The Old Terms
You’re still likely to hear people say “Asperger’s” as it was a very common diagnosis for a long time. There are also many adults who were diagnosed with Asperger’s in the past and are still identifying with that diagnosis today. Many more, having heard the term online, might still use it to describe themselves if that is what a clinician might currently call their disorder, namely Autism Spectrum Disorder Level 1.

In my work, I frequently work with adults who tell me, “I think I have Asperger’s.” What the person means when they tell me this, though, is that they have identified a set of challenges related to how they socialize and communicate.

They’ve done their homework. They want to know if they’re experiencing something and if there is a name for it, and if there is support for it. It is yes for both of those questions. The old terms are not incorrect, they’re just outdated. Using them in the assessment isn’t going to get you kicked out or make you unable to get the diagnoses that you need, because the clinician that you’re working with is going to know what you’re talking about and then be able to make those connections into DSM language. What causes problems is believing those old terms will determine the treatment you can access. The spectrum is a more inclusive approach, which looks at the nuances in strengths and deficits within people rather than fitting you into a box. If you are wondering if an Autism Spectrum Evaluation is the right choice for you or your child, knowing about this new way to think of autism that moved from four types to a spectrum is the first step to help you get answers.

How Is Autism Diagnosed Today: Severity Levels 1-3
If you have been reading about Autism Spectrum Disorder, you probably noticed that the old diagnosis of autism, Asperger’s syndrome, Pervasive Developmental Disorder-NOS (PDD-NOS), and Autistic Disorder are now only a few lines in the history books. Instead, clinicians throughout Minneapolis use the DSM-5 to provide one diagnosis: “Autism Spectrum Disorder” and one or more of the three severity levels. Severity levels refer to the level of support required for daily life for the person being diagnosed.

Here is what the three levels entail:

• Level 1: “Requiring support.” This is likely what many people refer to as “high functioning” autism, although the term is no longer used by clinicians. At this level, most people are able to engage in verbal conversation as well as functioning in their own independent lives. However, there are significant challenges related to social interaction and flexibility in behavior. They may need help organizing their lives and managing transitions between activities or projects. Many adults in Minneapolis were in high school, and beyond, who struggled socially in ways that they could never understand and never knew were symptoms of high-functioning autism, or level 1 autism.
• Level 2: “Requiring substantial support.” In this level, the differences in social communication with others become obvious to even casual observers. Verbal communications may be limited to simple sentences and may only focus on the child’s narrow interests. Changes in focus or transition in activities can cause difficulty. Repetitive behaviors may be noticeable to the observer. At this level, it is likely that accommodations will be necessary at school and at work.
• Level 3: “Requiring very substantial support.” This level refers to severe deficits in verbal and nonverbal communication. Independent functioning is affected. There are extreme difficulties in handling changes in routines. Repetitive behaviors are frequent to the point of interfering with functioning in all areas.

What many do not understand is that the three severity levels of autism are not fixed. A child who was diagnosed as a Level 2 could move closer to a Level 1 with the appropriate supports and services. For example, a Level 1 adult might need Level 2 support during a significant life transition, such as beginning employment in Uptown or navigating a divorce.

What a Formal Evaluation Looks Like
An accurate autism spectrum diagnosis involves much more than a screener quiz. Our typical autism spectrum evaluation includes standardized instruments, developmental history, behavioral observation, and clinical interviews. For children, we may meet with parents, teachers, and/or school staff. For adults, we assess your history of how you’ve accommodated and where challenges still occur.

We treat children in the Minneapolis metro area whose pediatricians noticed early signs, and we treat adults in their 30s and 40s who came upon an autism checklist on TikTok and started asking, “Hey wait, could I be an autistic adult?” Either way, both routes are good, and both deserve a quality answer.

The goal of an assessment is not to label a person in a box. It is to provide clarity so that one can receive appropriate services. A Level 1 diagnosis may lead to counseling focused on social and executive skill development. A Level 2 or Level 3 diagnosis may lead to multiple provider care coordination, including speech language, occupational therapy, and behavior health.

An important thing to remember is that levels represent levels of support needed and not intelligence or potential, which is a huge difference.

Curious to know if an autism spectrum evaluation could be appropriate for you or your child? Take a look at our autism spectrum evaluation page, which details what to expect during each phase of an assessment.