Last week, researchers at Princeton University published a groundbreaking research study about autism. There are a couple of things that make this such exciting news for anyone wanting to learn more about or better understand autism:

  • They were able to group behaviors and traits of autism into four distinct subtypes of autism. This will likely allow for more accurate diagnosis in the future.
  • They were able to identify related genetic markers for the different types, setting us up for further in-depth study of each one.
  • Some of the genes associated with certain subtypes are not activated until later in childhood, helping to explain why some autism symptoms do not show up until later in some people and why those people don’t receive a diagnosis until later than some other autistic individuals.

Where did they get their data?

Researchers for this study analyzed data from over 5000 children through the SPARK autism cohort study. SPARK stands for Simons Powering Autism Research for Knowledge and has been ongoing since 2016. Anyone in the U.S. who has received a professional diagnosis of autism and who can read/understand English or Spanish may participate in this study. (Just to be clear, this is not related in any way to any research that RFK, Jr. has discussed or proposed.)

One of the reasons SPARK is such a great project is that autistic adults and their families serve on their advisory board, are employed as staff, and also serve as community partners. As we often say, nothing about us without us.

SPARK currently has more than 380,000 participants, including 157,000 people with ASD and their first-degree family members. Over 31,000 participants in SPARK are autistic adults.

The 4 subtypes of autism

The Princeton research team used a person-centered approach to look at over 230 traits in each individual to then group the over 5000 participants into four subtypes. They grouped participants based on distinct developmental, medical, behavioral, and psychiatric traits, as well as different patterns of genetic variation.

Social and behavioral challenges

This was the largest group, accounting for 37% of the study participants. The social and behavioral challenges group exhibited social challenges and repetitive behaviors, but they did not experience any delays in developmental milestones. This group also often experienced co-occurring conditions like ADHD, OCD, anxiety, and depression. (For those of you wondering, this is my group!)

The genetic mutation associated with this group impacts a gene that is not activated until later in childhood. This likely explains the later presentation of this subtype of autism and why it might often go undiagnosed or not be diagnosed until much later.

Moderate challenges

The second-largest group, the moderate challenges group, accounted for 34% of the study participants. This group showed core autism-related behaviors less strongly, had no delay in meeting developmental milestones, and did not experience co-occurring conditions with their autism.

Mixed ASD with developmental delay

In this group – the third-largest subtype with 19% of participants – individuals often experienced delays in developmental milestones such as walking or talking compared to children without autism. They did not tend to show signs of anxiety, depression, or disruptive behaviors. “Mixed” in this instance refers to the variety of repetitive behaviors and social challenges within members of this subtype group.

When examining the genes associated with this subtype, researchers found that participants carried rare inherited genetic variants.

Broadly affected

The smallest group at only 10% of study participants, the broadly affected subtype has more difficult and wide-ranging challenges, including developmental delays, social and/or communication challenges, repetitive behaviors, and co-occurring conditions like mood dysregulation.

Participants in the broadly affected group also showed the highest number of genetic mutations that were not inherited from either parent.

What does all of this mean?

I’m sure there will be a lot of scientists able to review this data and explain it better than me, but there are a couple of important takeaways:

  • Because scientists were better able to define the distinct subtypes of autism and the genes associated with each, future research has a new jumping off point. Being able to start from this point will advance us even further into gaining a better understanding of autism.
  • The identification of the traits and behaviors – as well as the gene mutations – associated with these four subtypes of autism has the potential to improve our ability to diagnose autism and to fine-tune our existing diagnostic tools.

Though future research may identify more than just these four subtypes, we now know that at least four exist, and this is truly exciting news for everyone who is autistic or who supports autistic individuals. I can’t wait to see what else we learn in the coming years!