When ADHD and autism occur together, they can obscure each other, making both conditions harder to recognize and diagnose. A 2025 study estimated that roughly 45% of adults with ADHD show significant autistic traits, yet an analysis of 1.9 million U.S. insurance claims found that only 1.7% of adults with ADHD had a co-existing autism spectrum disorder (ASD) diagnosis. This gap reveals a growing problem: the overlap between these two neurodevelopmental conditions, often called "AuDHD" in autism and ADHD communities, is far more common than clinicians are catching. The story of how this overlap was discovered is telling. Colleen Cira, a clinical psychologist and founder of the Cira Center for Behavioral Health, first recognized her own ADHD while having her children assessed. She was diagnosed at age 35, but it took another seven years before she and her children received autism diagnoses. Her experience is increasingly common among adults whose symptoms went unnoticed earlier in life. The challenge is that these two conditions can work against each other in ways that make diagnosis particularly tricky. How Do ADHD and Autism Actually Overlap? ADHD and autism share certain features, particularly when it comes to attention and focus. Someone with autism might have special interests and hyperfocus on those topics, while someone with ADHD may struggle with regulating and sustaining attention but can also hyperfocus on interests. However, other traits pull in opposite directions. A preference for routine, which is common in autism, may conflict with the novelty-seeking and impulsivity associated with ADHD. For some people, this creates an internal tension between structure and change. "Someone with autism might have special interests and focus on those. Someone with ADHD may have difficulties regulating and sustaining their attention, but they can also have specialist interests so they can hyperfocus at times," explained Natasha Langan, clinical psychologist. Natasha Langan, Clinical Psychologist The presentation of AuDHD varies tremendously because autistic individuals and ADHD individuals vary tremendously. Cira uses a wine analogy to describe her particular blend: "I'm ADHD forward, that's the first thing you're going to see about me, with an autism finish." This variation makes it difficult for clinicians to recognize the pattern, especially when one condition masks the other. What Does the Brain Science Tell Us About AuDHD? Researchers are beginning to understand why these two conditions so often occur together. Both ADHD and autism are highly heritable, and growing evidence suggests they are partly rooted in shared biology rather than being entirely separate disorders. A large 2022 genomic study found that ADHD and autism share multiple regions of genetic risk, including at least seven genetic locations linked to both conditions, alongside others that differentiate them. Twin and family studies suggest a strong shared genetic signal between ADHD and autism, with some estimates indicating that much of the risk for one condition overlaps with the other. More recent neuroimaging work is mapping how those shared genes translate into brain structure and function. A 2025 neuroimaging study found that people with co-occurring ADHD and autism show distinct patterns of brain structure and connectivity, suggesting the combination is not just additive but may represent a unique neurodevelopmental profile. This finding points to what researchers describe as a "complex interplay of genetic, biological, and phenotypic factors" involved in AuDHD. Why Are So Many Cases of AuDHD Going Undiagnosed? Determining the true prevalence of AuDHD is difficult because researchers measure co-occurrence in different ways. Some studies look at shared traits, while others count only formal dual diagnoses, and the results can look dramatically different. A 2023 review found ADHD symptom prevalence varied from 2.6% to 95.5% in children and adolescents with autism spectrum disorder. A 2025 longitudinal study of 165 adults with ADHD found that 44.8% showed traits of autism. However, the insurance claims analysis suggests that many people have one diagnosis and show some traits of the other condition but not enough to meet the diagnostic threshold for a second diagnosis. Several factors contribute to widespread underdiagnosis. Until 2013, clinicians weren't even allowed to diagnose a person with both ADHD and autism. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders changed that, but many healthcare providers haven't yet caught up with assessment protocols for AuDHD. Additionally, symptoms of one condition can overshadow the other. When one condition becomes more evident, the other may be missed entirely. "Many clinicians are trained to try and understand what the primary concern is, so they may not see a necessity for an additional diagnostic label," noted Kelly Carrasco, psychologist and assistant professor at California State University, Fresno. Kelly Carrasco, Psychologist and Assistant Professor at California State University, Fresno Women and girls are particularly vulnerable to missing diagnoses. They often mask their symptoms better, knowing what the "right" way to behave and act is. As a result, people may come through mental health services with diagnoses of mood difficulties, depression, or anxiety that are actually rooted in undiagnosed neurodivergence. One condition might become more evident when the other subsides; for example, if you treat the ADHD, someone might be calmer, and then autism traits may start to become more apparent. Steps to Getting an Accurate AuDHD Assessment If you suspect you or your child may have both ADHD and autism, understanding the assessment process can help you advocate for comprehensive evaluation: - Seek a specialist trained in dual diagnosis: Look for clinicians who are familiar with AuDHD assessment protocols and understand how the two conditions interact, rather than clinicians trained to identify only one primary concern. - Provide detailed developmental history: Share information about childhood behavior, school performance, social interactions, sensory sensitivities, and attention patterns across different settings, as overlapping traits can be subtle. - Request comprehensive neuropsychological testing: Formal assessments should evaluate both ADHD and autism traits separately, looking for patterns that might indicate co-occurrence rather than just one condition. - Discuss masking and compensation strategies: Tell your clinician about any ways you've learned to hide symptoms or compensate for difficulties, as these adaptive behaviors can mask underlying neurodivergence. - Follow up after treatment begins: If one condition is treated and new symptoms emerge, return for reassessment, as treating ADHD may reveal previously hidden autism traits. What Does Treatment Look Like for AuDHD? There is no single treatment for AuDHD. Instead, care typically involves adapting existing approaches for ADHD and autism to reflect how the two conditions interact. This matters because co-occurring ADHD and autism are often linked to more complex health needs. The 2025 health insurance study found higher healthcare use and costs among people with both conditions, along with increased odds of additional health challenges. Understanding that someone has both conditions allows clinicians to tailor interventions more effectively. The implications are significant. As researchers continue to map the genetic, neurological, and behavioral overlap between ADHD and autism, the medical community is beginning to recognize AuDHD as a distinct presentation that requires its own assessment and treatment approach. For the millions of people living with both conditions, getting an accurate diagnosis could mean finally understanding why they feel "constantly at war" with themselves, and accessing support that actually addresses their unique needs.
