ADHD and Autism Spectrum Disorder: When Both Occur Together
ADHD and Autism Spectrum Disorder can occur simultaneously. This combination is clinically particularly relevant because symptoms can partially overlap, but in other respects, they can also be clearly distinguished. A recent review emphasizes that this comorbidity must not be overlooked. At the same time, careful differential diagnosis is necessary: Not every inattention or impulsivity in ASD is automatically ADHD, and not every social insecurity in ADHD already indicates an Autism Spectrum Disorder [1].
This is important for practice because the joint manifestation is often more complex than either of the two diagnoses alone. The review highlights that diagnosis and treatment should be individualized. This includes a clear clinical classification, differentiation from other mental disorders, and the decision about which symptoms actually impair daily life the most [1].
How common the comorbidity is in adulthood is shown by a large population-based cohort study inJAMA Network Open. There, ADHD diagnoses were found in 26.7% of autistic adults without intellectual disability and in 40.2% of autistic adults with intellectual disability. In the general Medicaid population, the corresponding value was 2.7%. This underscores that ADHD in autistic adults is not a marginal phenomenon, but a very relevant accompanying condition [2].
The co-occurrence is not only diagnostically significant but also medically important. In the same study, negative health outcomes were more common among autistic adults with additional ADHD. The rate of substance use disorders among autistic adults with ADHD was13.2 %, compared to 5.7 % among autistic adults without ADHD. Additionally, ADHD diagnoses were overall associated with higher rates of unfavorable health outcomes. The authors also report that ADHD medication was associated with lower rates of certain negative health events, which is relevant for clinical treatment [2].
This makes it clear: The comorbidity of ADHD and ASD is more than a formal dual diagnosis. It can be associated with greater functional impairment, higher treatment needs, and more complex care. For those affected, this means that both disorders should be actively considered – both diagnostically and therapeutically [1][2].
Conclusion
When ADHD and ASD occur together, clinical complexity increases significantly. Current evidence suggests that this comorbidity is common and may be associated with poorer health outcomes. Therefore, careful diagnostics, individualized treatment, and care that simultaneously considers both disorders are all the more important [1][2].
Literature
[1] Petruzzelli MG, et al.An update on the comorbidity of attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) and its clinical management. Expert Review of Neurotherapeutics. 2026;26(1):75–89. (PubMed)
[2] Yerys BE, et al.Attention-Deficit/Hyperactivity Disorder in Medicaid-Enrolled Autistic Adults. JAMA Network Open. 2025;8(2):e2453402. (PubMed)