Autism and ADHD: Similarities, Co-occurrence, and What It Means for Your Child
Dr. Rachel Weinstein
(BCBA-D)
Rachel started as a special education teacher in Brooklyn before earning her...
Autism Spectrum Disorder (ASD) and ADHD are two of the most commonly diagnosed neurodevelopmental conditions in children — and two of the most frequently confused with each other. They share real features, they often occur together in the same child, and when they do, the combined picture is more complex than either condition alone.
This guide covers what the two conditions have in common, how to tell them apart, what co-occurrence actually looks like clinically, and what it means for treatment.
What autism and ADHD have in common
Both ASD and ADHD affect attention, impulse control, social interaction, and sensory processing — which is why they can look strikingly similar, especially in early childhood. Genetic research puts heritability for both conditions at approximately 70–80%, and large-scale studies have identified shared genetic risk factors including 207 candidate genes implicated in both disorders.¹
The most consistently overlapping features include:
Attention difficulties. Both conditions cause problems with sustaining focus and completing tasks, though the mechanism differs — more on that below.
Impulse control. Difficulty inhibiting impulsive actions appears in both, though it is more consistently defining in ADHD.
Social difficulties. Both can result in challenges reading social cues and navigating peer relationships, though for different underlying reasons.
Sensory sensitivities. Over- or under-reacting to sensory input is common in both ASD and ADHD, and is now formally included in the DSM-5-TR diagnostic criteria for ASD.
Hyperactivity. More consistently present in ADHD, but some autistic children also display hyperkinetic behavior.
Where they differ
The surface similarities are real, but the underlying mechanisms are distinct — and that distinction is what guides treatment.
In ASD, attention tends to be highly focused and sustained on preferred topics or activities, while attention to social stimuli and joint attention are specifically impaired. Repetitive behaviors, restricted interests, and difficulties with social communication and interaction are core features that are not characteristic of ADHD. Autistic individuals often find repetitive behaviors regulatory and self-consistent — they feel natural, not distressing.
In ADHD, the core difficulties are with sustaining attention broadly, controlling impulse, and regulating activity level. Social difficulties, where present, typically stem from impulsivity and distractibility rather than from deficits in social understanding.
Compulsive behaviors in ADHD, when present, are driven by anxiety and feel ego-dystonic — unwanted, even as the person feels compelled to perform them.
| Feature | ASD | ADHD |
|---|---|---|
| Attention | Sustained on preferred topics; impaired orientation to social stimuli | Broadly difficult to sustain; easily distracted |
| Social difficulties | Core feature — social communication deficits | Present but secondary to impulsivity/inattention |
| Hyperactivity | Less prominent | Core feature |
| Repetitive behaviors | Core feature, often self-regulatory | Not a defining feature |
| Sensory sensitivities | Core feature (DSM-5-TR) | Common but not defining |
How often do they co-occur?
The co-occurrence rate is substantial. Research estimates that ADHD is present in 32–50% of children diagnosed with ASD, while ASD features appear in approximately 9–20% of children diagnosed with ADHD.²
In the school-age population, the estimated prevalence of true comorbid ASD and ADHD is approximately 0.51%, though parent and teacher reporting rates are higher — 3.2% and 2.6% respectively — reflecting the difficulty of distinguishing the conditions in everyday observation.³
Sex differences are pronounced. The comorbid prevalence rate for boys is estimated at 0.89%, compared to 0.16% for girls.³ This gap likely reflects both genuine diagnostic differences and the well-documented under-identification of girls in both conditions.
Despite the high co-occurrence rate, only 15.8% of children with both conditions had previously
received dual diagnoses — suggesting that comorbidity is significantly underidentified in clinical practice.³
Genetic overlap: what the research shows
The New Jersey Language and Autism Genetics Study (NJLAGS), which analyzed whole-genome sequencing data from 272 samples across 73 families with at least one ASD-affected member, identified 207 candidate genes associated with both ASD and ADHD.¹ Within linkage regions on chromosomes 12 and 17, 36 genes specifically associated with ADHD were identified. The highest-ranking gene on chromosome 17 was KDM6B — a well-established risk gene for neurodevelopmental disorders including both ASD and ADHD.
Additional research has identified SHANK2 as a potential pleiotropic gene contributing to the high co-occurrence of the two conditions, with specific SHANK2 alleles found to reduce disease risk for both by approximately 20–30%.⁴
This genetic overlap does not mean the conditions are the same — it means they share biological pathways that increase risk for both, which is consistent with their distinct but overlapping clinical presentations.
What co-occurrence means for daily functioning
When both conditions are present, the combined impact on daily life is more severe than either alone. Children with comorbid ASD and ADHD consistently show:⁵
- Lower cognitive functioning compared to ASD-only peers
- More severe social impairments
- Greater delays in adaptive functioning
- Lower scores across psychosocial, emotional, and school functioning measures
- Higher rates of co-occurring anxiety, depression, and behavioral difficulties
The internal experience can also create a specific kind of conflict: ADHD's impulsivity and hyperactivity can clash directly with the autistic preference for routine and predictability, creating dysregulation that neither condition alone would produce to the same degree.
Treatment when both conditions are present
Co-occurring ASD and ADHD generally requires a more individualized approach than either condition treated in isolation, because standard treatments for each are less effective when the other is also present.⁵
Behavioral approaches. Applied Behavior Analysis (ABA) is the most evidence-based behavioral intervention for ASD and can be adapted to address attention, impulse control, and executive function targets relevant to ADHD. Cognitive Behavioral Therapy (CBT) and parent training are also used, particularly for emotional regulation and social skills.
Medication. There are no medications specifically approved for ASD core symptoms. For ADHD symptoms in the context of ASD, methylphenidate and atomoxetine are the most commonly prescribed options, though tolerability can be more variable in autistic children and dosing may need closer monitoring. Risperidone and aripiprazole are FDA-approved for irritability associated with ASD but are not primarily ADHD treatments.
Collaborative planning. When both conditions are present, the most effective outcomes come from BCBAs, pediatricians, psychologists, teachers, and parents working from the same individualized plan — not treating the conditions in parallel without coordination.
If your child has received a diagnosis of ASD, ADHD, or both and you're navigating what that means for therapy, Achieve Behavioral Therapy's BCBAs provide individualized assessments and ABA programmes across New Jersey, North Carolina, Georgia, Colorado, Nebraska, and Arizona.
Contact us today to learn how our in-home and school-based ABA therapy can help your child thrive in the community.
Frequently Asked Questions
What are the main similarities between autism and ADHD?
Both conditions affect attention, impulse control, social functioning, and sensory processing. They also share significant genetic overlap, with heritability estimated at 70–80% for both. These similarities mean they can look alike — particularly in early childhood — and are one reason accurate diagnosis requires comprehensive clinical evaluation rather than symptom checklists alone.
Can a child have both autism and ADHD at the same time?
Yes. Research estimates ADHD is present in 32–50% of autistic children, and ASD features appear in approximately 9–20% of children diagnosed with ADHD. When both are present, the combined impact on daily functioning, social development, and treatment responsiveness is generally more significant than either condition alone.
Why do autism and ADHD often get confused?
The overlapping surface features — inattention, impulsivity, social difficulties, sensory sensitivities — can look identical from the outside. The distinction lies in what's driving the behavior: in ASD, repetitive behaviors and social difficulties stem from neurodevelopmental differences in social processing and sensory regulation; in ADHD, the core driver is dysregulation of attention and impulse control. Accurate diagnosis requires assessment of both the behavioral profile and the mechanisms underneath it.
How does treatment differ when a child has both conditions?
Children with both ASD and ADHD are generally less responsive to standard treatments designed for either condition alone. ABA can be adapted to address both behavioral and attention-related goals. Medication for ADHD symptoms may be used alongside behavioral therapy, though tolerability varies and requires careful monitoring. The most effective approach involves coordinated planning across all providers — BCBA, physician, school team, and family.
Sources
- Buxbaum Grice, A., et al. (2023). Whole genome sequencing implicates KDM6B in ADHD comorbid with ASD.
PMC10177627. https://pmc.ncbi.nlm.nih.gov/articles/PMC10177627/
- Leitner, Y. (2014). The co-occurrence of autism and attention deficit hyperactivity disorder in children.
Frontiers in Human Neuroscience. https://pmc.ncbi.nlm.nih.gov/articles/PMC4010758/
- Prevalence and sex differences in comorbid ASD and ADHD.
PMC3441928. https://pmc.ncbi.nlm.nih.gov/articles/PMC3441928/
- Tammimies, K., et al. (2023). SHANK2 as a pleiotropic gene in ASD and ADHD comorbidity.
PMC8918663. https://pmc.ncbi.nlm.nih.gov/articles/PMC8918663/
- Antshel, K. M., & Russo, N. (2019). Autism spectrum disorders and ADHD: Overlapping phenomenology, diagnostic issues, and treatment considerations.
Current Psychiatry Reports. https://pubmed.ncbi.nlm.nih.gov/38695661/
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