ADHD and Autism Overlap: How to Tell the Difference
In my work with clients and families, I hear a version of the same question all the time: "Could this be ADHD, or is it autism? Can someone have both?" It's a fair question. ADHD (Attention-Deficit/Hyperactivity Disorder) and Autism Spectrum Disorder (ASD) can look remarkably similar on the surface. So today I want to walk through where these two conditions overlap, where they diverge, and why getting the distinction right matters so much for assessment and treatment.
How Often Do ADHD and Autism Overlap?
More often than most people expect. Population studies estimate that ADHD is present in roughly 30% to 80% of individuals with ASD, while ASD traits show up in about 20% to 50% of individuals with ADHD — even though ADHD affects an estimated 5–7% of the population and ASD affects around 1.5% on their own (Miodovnik et al., 2019, as cited in the Journal of Autism and Developmental Disorders literature). A more recent systematic review found comorbidity estimates in pediatric populations ranging from 30% to 50%, with shared inattention and executive functioning difficulties frequently complicating an accurate differential diagnosis (Frontiers in Psychiatry review, 2025).
This overlap wasn't always formally recognized. Under the DSM-IV, clinicians weren't permitted to diagnose ADHD in someone who already had a pervasive developmental disorder diagnosis, because ADHD-like symptoms were assumed to be part of the autism presentation. The DSM-5 changed that, allowing both diagnoses to be given together — opening the door to a much better understanding of how these two conditions can coexist (Ronald et al., as discussed in Mikami & colleagues' scoping review literature).
Where ADHD and Autism Look Alike
It's easy to see why these conditions get confused for one another. Both can involve:
Difficulty sustaining attention or following multi-step directions
Trouble with cognitive flexibility and shifting between tasks
Sensory sensitivities
Social difficulties that affect friendships and peer relationships
Emotional outbursts, particularly around transitions or unexpected changes
A systematic review in the Review Journal of Autism and Developmental Disorders found overlapping symptom domains across attention, behavior regulation, social communication, sensory sensitivity, and cognitive flexibility between the two populations. That overlap helps explain why children are sometimes misdiagnosed, or why one diagnosis gets missed entirely when the other is more obvious.
Where ADHD and Autism Diverge
Despite the surface-level overlap, the underlying mechanisms driving these behaviors tend to differ in important ways.
Social difficulties come from different places. In ADHD, social struggles are frequently secondary to impulsivity and inattention. A child with ADHD may genuinely want to connect with peers but interrupt conversations or miss subtle cues in the moment. In ASD, social communication differences are a core, defining feature rather than a byproduct of distractibility — involving more fundamental differences in how social information and nonverbal cues are processed and understood. Research examining theory of mind found that behavioral regulation processes, like inhibition and emotional control, are more closely tied to social cognition in children with ADHD, while metacognitive skills such as planning and initiation are more strongly linked to social cognition in children with high-functioning autism (PMC5481358).
Response inhibition looks different, too. A 2024 study using detailed attention testing found that impaired response inhibition — the ability to stop an automatic or impulsive response — was significantly more pronounced in the ADHD and combined ADHD+ASD groups than in the ASD-only group. This suggests that difficulty putting the brakes on impulses is more central to ADHD's presentation than to autism's (Frontiers in Psychiatry, 2024).
Executive function plays a different role in each. ADHD has long been understood partly as a disorder of executive functioning, particularly inhibition and working memory. In ASD, executive function difficulties are common but aren't considered a core diagnostic feature — they tend to be intertwined with social cognition and the restricted, repetitive patterns of behavior and interests that are central to an autism diagnosis (systematic review and meta-analysis, PMC11049008).
Why Getting the Diagnosis Right Matters
This distinction isn't just an academic exercise — it directly shapes treatment planning. Children and adolescents with co-occurring ADHD and ASD tend to experience more severe social and cognitive impairment, along with a higher risk of anxiety, mood difficulties, and academic struggles, compared to children with either condition alone (PMC12437639). Because of this, a multidisciplinary, tailored approach — one that may combine behavioral strategies, cognitive-behavioral therapy adapted to the individual's needs, executive function coaching, and, when appropriate, medication management — tends to produce the best outcomes (Psychiatric Annals, 2026).
Comprehensive assessment that looks closely at both attentional and social-communication domains, rather than relying on a single behavior checklist, is essential for catching a co-occurring diagnosis that might otherwise be missed.
Frequently Asked Questions
Can you have both ADHD and autism? Yes. The DSM-5 allows both diagnoses to be given together, and research shows meaningful overlap between the two — anywhere from 30% to 80% of individuals with ASD also meet criteria for ADHD, depending on the study population.
How can I tell if it's ADHD, autism, or both? A comprehensive evaluation looking at both attentional and social-communication domains is the only reliable way to tell. Surface-level symptoms like inattention, sensory sensitivity, and difficulty with transitions can show up in either condition, so a single checklist isn't enough to differentiate them.
Does ADHD or autism cause more social difficulties? Both can affect social relationships, but for different reasons. In ADHD, social struggles usually stem from impulsivity and inattention. In ASD, social communication differences are a core feature of the condition itself, not a side effect of distractibility.
Final Thought
If you or someone you love has ever wondered whether a diagnosis fully captures what's going on, you're not alone in asking that question — and the research supports that instinct. ADHD and autism can and do coexist, and disentangling them takes a thoughtful, comprehensive evaluation rather than a quick checklist. If you have questions about assessment or would like to talk through next steps, I'd love to hear from you.
This post is intended for educational purposes and is not a substitute for individualized clinical assessment.
References Comprehensive comorbidity systematic review (PMC): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12437639/ An update on the comorbidity of ADHD and ASD, Expert Review of Neurotherapeutics (2025): https://www.tandfonline.com/doi/full/10.1080/14737175.2025.2599856 Zhong Q, Porter M. — Review Journal of Autism and Developmental Disorders: https://link.springer.com/article/10.1007/s40489-024-00443-4 Response inhibition study, Frontiers in Psychiatry (2024): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11574416/ Sex Differences in Social Adaptive Function (PMC): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6751776/ Social Cognition in Children with High-Functioning ASD and ADHD (PMC): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5481358/ Executive Functions Systematic Review and Meta-Analysis (PMC): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11049008/ Psychiatric Annals (2026): https://journals.healio.com/doi/10.3928/00485713-20260113-03