Yes, it is absolutely possible to have both ADHD and autism, and the combination is common. Between 50 and 70% of autistic individuals also meet the criteria for ADHD. The two conditions share genetic roots, overlapping brain differences, and many surface-level symptoms, which is why they so frequently travel together.
Why This Wasn’t Always Recognized
Until 2013, the official diagnostic manual used by psychiatrists in the United States (the DSM) did not allow a person to be diagnosed with both ADHD and autism. If you had an autism diagnosis, clinicians were instructed to attribute attention and hyperactivity problems to the autism itself rather than recognizing ADHD as a separate, co-occurring condition. The DSM-5, published in 2013, explicitly changed this rule: a comorbid diagnosis with autism spectrum disorder is now allowed for ADHD.
The World Health Organization followed a similar path. The ICD-11, its current diagnostic framework, takes an even more direct approach than the DSM-5. Rather than listing ADHD under “differential diagnosis” (conditions autism might be confused with), it includes ADHD in a section called “Boundaries with Other Disorders and Conditions,” acknowledging that the two frequently co-occur across the lifespan. These changes in both major diagnostic systems mean that anyone evaluated today can receive both diagnoses if they meet the criteria for each.
The Genetic Connection
The overlap between ADHD and autism isn’t coincidental. Twin studies estimate that 50 to 72% of the traits shared between the two conditions can be traced to common genetic factors. Researchers have identified dozens of genetic markers associated with both, particularly in regions of chromosomes 5, 9, and 16. Genes involved in dopamine signaling (long linked to ADHD) have been studied for connections to autism, while serotonin-related genes (traditionally associated with autism) show potential links to ADHD as well.
In rarer cases, specific genetic variations can directly produce both conditions. Certain mutations on the X chromosome, duplications on chromosome 15, and deletions on chromosome 22 have all been identified in individuals who have both ADHD and autism. These aren’t the cause for most people with the dual diagnosis, but they illustrate how deeply intertwined the biological foundations of these two conditions are.
Where Symptoms Overlap
ADHD and autism share a wide range of traits, which is one reason they co-occur so often and one reason they’re difficult to tell apart. Both conditions involve differences in executive function, the set of mental skills you use to plan, organize, stay focused, and regulate your behavior. Children and adults with either condition tend to perform worse than neurotypical peers on tasks measuring working memory, impulse control, and the ability to switch between tasks. Both groups also show difficulties with organizational skills, persistence on tasks, emotion regulation, and self-control of motor activity.
Social difficulties appear in both conditions too, though for different reasons. Autistic individuals often have core differences in social cognition, meaning they may process social cues, facial expressions, and emotional signals differently at a fundamental level. People with ADHD also struggle socially, but this tends to stem from impulsivity, inattention during conversations, or difficulty reading anger and fear in others rather than a broader difference in social processing. When someone has both conditions, these social challenges compound each other.
How Clinicians Tell Them Apart
Distinguishing ADHD from autism is genuinely difficult, even for experienced clinicians. The core features of one condition can mimic behaviors typically seen in the other. A child who doesn’t respond when spoken to might be inattentive (ADHD) or might be processing social communication differently (autism). A child who struggles to make friends might lack social motivation (autism) or might be too impulsive and disruptive to maintain friendships (ADHD).
A few patterns help clinicians tease the two apart. Executive function problems tend to be more severe in ADHD, and they generally don’t improve much with age. In autism, executive function difficulties often show some improvement over time. Emotion recognition deficits also differ: autistic individuals tend to have broader difficulty recognizing emotions across the board and may lack the typical physiological responses (like changes in heart rate) when seeing someone else’s emotional expression. People with ADHD have a more specific pattern, struggling most with identifying anger and fear. When a person shows the full picture of both, that points toward a dual diagnosis rather than one condition being mistaken for the other.
Why Women and Girls Are Often Missed
The dual diagnosis is particularly likely to be missed or delayed in women and girls. Autistic females tend to be more skilled at camouflaging, a set of behaviors that involves copying social scripts, carefully monitoring one’s own eye contact and facial expressions, and forcing social interaction to appear more typical. Researchers break camouflaging into three strategies: compensation (using learned scripts and mimicking others), masking (suppressing autistic traits and presenting a non-autistic persona), and assimilation (using deliberate techniques to fit in socially).
Women are generally more competent at masking their symptoms from observers, which leads to later diagnoses and fewer opportunities for support. The ADHD component adds another layer of invisibility. In females, ADHD symptoms are more likely to center on attention difficulties rather than the hyperactivity and impulsivity that typically prompt referrals in boys. The cost of sustained camouflaging is real: it is associated with higher rates of depression, anxiety, and burnout.
How Treatment Differs With Both Conditions
Managing ADHD when autism is also present requires some adjustment in expectations. Stimulant medications, the standard ADHD treatment, do work for many autistic individuals, but the picture is more complicated than it is for people with ADHD alone. About 49% of autistic children with ADHD respond well to stimulants for hyperactivity symptoms, and overall favorable response rates reach around 69%. That’s meaningful, but the response rate tends to be lower than in people with ADHD only.
Side effects also require closer attention. Autistic individuals on stimulants experience higher rates of adverse effects severe enough to stop treatment. In one study, 18% of participants dropped out due to intolerable side effects. Irritability is a particular concern, though the relationship is nuanced: low doses don’t appear to increase irritability, and moderate doses may actually decrease it. Higher doses are where irritability becomes more common, affecting up to 70% of participants in some studies, though placebo rates were also high at 63%. The practical takeaway is that starting at lower doses and increasing gradually tends to work better for people with both conditions.
Beyond medication, the combination of ADHD and autism often means that strategies designed for one condition alone fall short. Social skills interventions built for autistic individuals may not account for the impulsivity and distractibility of ADHD. Organizational systems designed for ADHD may not address the rigid thinking patterns or sensory needs that come with autism. The most effective approaches tend to be those tailored to the specific profile of challenges a person actually has, rather than following a playbook written for either condition in isolation.