- Many autistic people have at least one co-occurring condition; one study found 70 percent of autistic children aged 10 to 14 did.
- ADHD, anxiety, sensory processing differences, and gut issues commonly overlap with autism.
- The DSM-5 finally allowed dual autism and ADHD diagnosis starting in 2013.
- Ask clinicians to evaluate for co-occurring conditions so support addresses the full picture.
Autism does not exist in isolation. Many autistic people have at least one co-occurring condition, another neurological, psychiatric, or physical condition that intersects with and complicates their autistic experience. In one population-based study of autistic children aged 10 to 14, 70 percent had at least one co-occurring psychiatric condition.
Understanding what those co-occurring conditions are, and how they interact with autism, is essential for families trying to understand their child and get appropriate support.
ADHD
ADHD is one of the most common co-occurring conditions in autism. In a 2019 meta-analysis of 96 studies, ADHD had the highest pooled prevalence among the co-occurring psychiatric conditions studied, at 28 percent. Other estimates run higher: a 2021 meta-analysis found a pooled lifetime rate of about 40 percent, and a 2022 review notes that the literature commonly cites 50 to 70 percent. The two conditions share several features, difficulties with sustained attention, impulsivity, executive function challenges, but they are neurologically distinct.
For a long time, the DSM did not allow dual diagnosis of autism and ADHD. This changed when the DSM-5 was published in 2013. Before that, many children with both conditions were diagnosed with one and missed the other, meaning their treatment and support addressed only part of what they were dealing with.
The interaction of autism and ADHD is complex, and each can affect how the other presents. Both conditions affect executive function. Getting an accurate picture of what is happening requires evaluation that looks at both.
Anxiety
Anxiety is very common in autistic people. A meta-analysis of 31 studies found 39.6 percent of autistic young people under 18 had at least one anxiety disorder, and a meta-analysis of studies in autistic adults found a current anxiety disorder in 27 percent and a lifetime anxiety disorder in 42 percent. And it makes sense: navigating a world designed for neurotypical processing, while masking, managing sensory overwhelm, and dealing with unpredictability, is anxiety-producing.
But anxiety in autistic people can look different than anxiety in neurotypical people, and this can lead to misdiagnosis. An autistic person whose anxiety manifests as insistence on routine and resistance to change may be diagnosed as having a behavior problem rather than an anxiety disorder.
Treating anxiety in autistic people requires approaches that account for the autistic nervous system. Standard cognitive behavioral therapy may need modification. Many families find that sensory accommodations that reduce overall load, along with predictability and routine, help ease day-to-day anxiety.
Sensory Processing Disorder
Sensory processing differences are now part of the diagnostic criteria for autism, but some children have sensory processing difficulties that do not meet the full criteria for autism diagnosis. Occupational therapy with a sensory integration focus can be helpful for both.
Gastrointestinal issues
Autistic children have more gastrointestinal symptoms than other children: a 2014 meta-analysis found about four times the odds of GI symptoms overall, including higher odds of constipation, diarrhea, and abdominal pain. These can contribute to behavioral and emotional regulation difficulties in ways that are sometimes misattributed to the autism itself.
What this means for families
If your child has been diagnosed with autism, it is worth asking the evaluating clinician whether there may be co-occurring conditions that should also be evaluated. An incomplete picture leads to incomplete support. A full picture leads to better interventions, better accommodations, and a better understanding of what your child is actually dealing with every day.
Frequently Asked Questions
Is it common for autistic people to have other conditions too?
Yes. Many autistic people have at least one co-occurring condition, whether neurological, psychiatric, or physical. In one population-based study of autistic children aged 10 to 14, 70 percent had at least one co-occurring psychiatric condition. Understanding these conditions helps families get a more accurate picture and avoid partial or mistaken support. An incomplete picture leads to incomplete support.
How often do autism and ADHD occur together?
ADHD is one of the most common co-occurring conditions in autism. A 2019 meta-analysis put its pooled prevalence at 28 percent, a 2021 meta-analysis found a lifetime rate of about 40 percent, and the literature commonly cites 50 to 70 percent. The two are neurologically distinct but share features like attention difficulties, impulsivity, and executive function challenges. Dual diagnosis was not allowed until the DSM-5 in 2013, so before then many people were diagnosed with one and missed the other.
Why is anxiety so common in autistic people?
A meta-analysis found 39.6 percent of autistic young people had at least one anxiety disorder, and a meta-analysis of autistic adults found a lifetime rate of 42 percent. That makes sense given the demands of navigating a world built for neurotypical processing while masking and managing sensory overwhelm. Autistic anxiety can look different, sometimes appearing as insistence on routine or resistance to change, which can lead to misdiagnosis. Many families find sensory accommodations, predictability, and routine help ease it.