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Maxfield Sparrow


Sometimes when I’m talking with someone about autism it feels like we’re talking about two different things. For example, I’ve had countless conversations that go something like this:

“You’re nothing like my child. My child has the serious kind of autism,” they might open with. 

“Autism is serious stuff,” I respond. “It’s important to take it seriously.” 

“No, I mean my child has the autism with digestive stuff and physical involvement. The severe autism.” 

“I have intermittent gastroparesis that has sent me to the hospital multiple times. I have a connective tissue disorder that has caused pelvic organ prolapse. These things aren’t autism.”

And it’s the truth: the co-occurring conditions we cope with are not autism; they are the “genetic hitchhikers” that love to travel with autism. Even being non-speaking—a trait that some people view as the true core of autism—is due to conditions that more frequently occur among those of us with developmental disabilities such as autism or cerebral palsy. However it is not autism itself that prevents speech, but rather these “hitchhikers” like apraxia and extreme sensory processing issues.

Questions immediately arise: how many of these commonly co-occurring conditions are there? How prevalent are the conditions that tend to accompany autism? And if autism is not simply a cluster of co-occurring conditions, then what is it?

The August 2018 issue of The Journal of Autism and Developmental Disorders is publishing a paper called Prevalence of Co-occurring Medical and Behavioral Conditions/Symptoms Among 4- and 8-Year-Old Children with Autism Spectrum Disorder in Selected Areas of the United States in 2010, written by researchers from the Center for Disease Control and the University of Arizona.

While this paper barely brushes on that third question: what is autism really? (“Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by deficits in social communication and interaction and the presence of restricted and repetitive patterns of behaviors, interests, and activities (American Psychiatric Association 2013).”), it does go a long way toward addressing the first two questions about the number and prevalence of co-occurring conditions in autistic children.

How the Study was Conducted

The study collected information in the Autism and Developmental Disabilities Monitoring Network (ADDM) from the calendar year 2010. ADDM is a project that has been tracking eight-year-old autistic children since 2000, and added four-year-old children, starting in select areas, in 2010.

The researchers collected their data by looking only at the five sites that had included data from four-year-old autistic children that year (Arizona, Missouri, New Jersey, Utah, and Wisconsin). They pulled all the records of children diagnosed autistic and verified the diagnoses using DSM-IV-TR criteria (that being the standard diagnostic criteria used in 2010).

The paper claims this study is the first one to look at two age groups of autistic children using a large sample and studying a diverse group of co-occurring conditions. One of the biggest things the researchers discovered was that eight-year-olds had more co-occurring conditions than four-year-olds, and more than 95% of the children had at least one co-occurring condition.

The researchers report that the wide variety of co-occurring conditions and the great diversity among the children, as far as what patterns of co-occurring conditions each child exhibited, often contributed to difficulties in accessing autism diagnoses. They noted that a very small fraction of children had no co-occurring conditions. While they could not explain why autism tends to come along with so many, varied co-occurring conditions, the researchers noted that the varying patterns of co-occurring conditions make autism very heterogeneous—that is to say, each autistic person has a specific pattern of strengths and weaknesses that is often quite different from other autistic people.

This pronounced variety can make it harder for people to get diagnosed as autistic, especially early in life when there is no single marker of autism or autistic behavior. The authors suggested including co-occurring conditions in the autism screening procedures, in order to catch more autistic children who are slipping through the diagnostic cracks. The variety also cautions against seeking one-size-fits-all systems to address autistic needs.

Some Statistics From the Study

The data was analyzed statistically and measures were taken to mathematically account for the following factors: sex, race-ethnicity, maternal education, and geographical location of the study. All statistics I am mentioning in this article are ones that were statistically significant—that is, the differences were large enough for the researchers to pay attention to them as actual signals, rather than just random differences that don’t mean much.

The researchers looked at the following eighteen items that they determined to be the most common co-occurring conditions found among autistic people:

  1. Developmental disability – cognitive
  2. Congenital conditions (cerebral palsy, encephalopathy, vision impairment, hearing loss)
  3. Self-injurious behaviors
  4. Sensory integration disorder
  5. Developmental regression
  6. Epilepsy/seizure disorder
  7. ADHD
  8. Oppositional Defiant Disorder
  9. Anxiety
  10. Aggression
  11. Language disorder
  12. Sleep abnormalities
  13. Developmental disability – motor
  14. Genetic conditions (Down syndrome, Fragile X syndrome, Tuberous sclerosis)
  15. Mood disorder
  16. Developmental disability – adaptive
  17. Abnormalities in eating, drinking
  18. Temper tantrum

One thing they found was that some co-occurring conditions (gastrointestinal problems, sleep problems, and epilepsy) seemed to intensify the core traits of autism while others (ADHD, ODD, and aggression) appeared to “mask” autism traits, often resulting in a later diagnosis.

They also found that autistic children with intellectual disability were more likely to be diagnosed before age six than autistic children without intellectual disability.

The eight-year-olds had more cases of twelve of the above eighteen co-occurring conditions, but only eight of these were statistically significant: ADHD, Oppositional Defiant Disorder, anxiety, aggression, language disorder, sleep abnormalities, motor disability, mood problems.

The eight-year-olds had an average of 4.9 co-occurring conditions, and 98% of them had at least one co-occurring condition.  The four-year-olds had an average of 3.8 co-occurring conditions, and 96% of them had at least one co-occurring condition.

The statistically significant conditions that caused children to be diagnosed earlier were: Developmental regression, developmental disability – adaptive, abnormalities in eating and drinking, developmental disability – cognitive, temper tantrums, developmental disability – motor, and self-injurious behaviors. Those conditions that caused children to be diagnosed autistic later were: ADHD, oppositional defiant disorder, and anxiety.

The most prevalent co-occurring conditions according to the study were: Mood disorder (75.4%), Anomalies in eating and drinking (61%), Temper tantrums (56.5%), Aggression (55.40%), and Sleep abnormalities (40.7%).

Something that surprised me about the study were the co-occurring conditions with prevalence far lower than I had expected to see. These include: Developmental disability – cognitive (present in 15.6% of the autistic children in the study), Self-injurious behaviors (27.3%), Sensory integration disorder (10.1%), Language disorder (35.5%), Epilepsy (3.6%), and Anxiety (12%).

Analysis and Discussion of the Implications of the Study

The findings of this study could change the way autism is understood and diagnosed, which is important. While other researchers have looked at co-occurring conditions in autism, this is the first thorough survey of them, even though it is not entirely representative of the entire United States since the sample was not chosen completely randomly.

Before this study, the only academic writing I was aware of that looked at co-occurring conditions in such depth is Polly Samuel/Donna William’s work on the “Fruit Salad Theory of Autism” which is found in detail in her book The Jumbled Jigsaw, or in summary in her blog post “What is Autism?

Many Autistic activists express the importance of viewing co-occurring conditions as something separate from autism itself. As I mentioned above, I sometimes call them “genetic hitchhikers” because the anxiety, stomach problems, sleep issues, etc. are not autism, and are found among people who are not autistic, though we seem to have them with more intensity and/or higher frequency than the general population. These co-occurring complications can make the overall picture of autism look very different from person to person, and may necessitate a lot of support, accommodation, and assistance for us to navigate and manage.

People who have a hard time understanding why we say we are proud to be Autistic and don’t want or need our autism to be taken away often feel that way because they have defined “autism” as “the cluster of co-occurring conditions experienced by the autistic people I know or have heard of.” Research like this new study important for the implications in the medical world, with respect to diagnosis and therapies, but it’s equally important for those of us in the lay community who are trying to communicate across a gap of understanding—a gap caused by people defining autism in radically different ways.

Hopefully this research and similar research that will follow and build upon this foundation will help those of us in the Autism community (that community made up of everyone from Autistic people to our families to therapists to researchers and beyond) to agree upon shared definitions of autism. This will be a necessary first step, before we can really get down to meaningful dialogue across the gaps in our lived experiences: the lived experience of being autistic and the experience of loving or working with someone who is. We in one or more of those groups can and very much should seek to unite with the others because we are stronger together. Coming to a place of mutual understanding of the foundational nature of autism will start us down that path, toward joining our forces to change the world.