When It's Both: Understanding ADHD and Autism Together

For a long time, you couldn't officially have both.

Until 2013, the diagnostic criteria for autism actually excluded an ADHD diagnosis; clinicians were instructed to choose one or the other, even when both seemed to fit. That rule is gone now, and what research has revealed since is striking: somewhere between 50 and 70 percent of autistic people also meet criteria for ADHD, and a significant portion of people with ADHD show traits that point toward autism as well.

Which means many people spent years, sometimes decades, with half the picture.

If you have an ADHD diagnosis that has never quite explained everything, or an autism diagnosis that left some things still unaccounted for, or you've been reading about AuDHD online and wondering if it fits, this post is for you.

Why the Two Conditions Were Kept Separate for So Long

The assumption for many years was that autism and ADHD were distinct enough that they wouldn't meaningfully overlap. ADHD was framed primarily as an attention and impulse control problem. Autism was framed primarily as a social communication difference. They seemed to involve different systems.

What that framing missed is how much these conditions share at the neurological level and how differently both can present depending on the person. Attention difficulties, executive function challenges, sensory sensitivities, and social struggles show up in both conditions, in varying combinations and degrees. Separating them neatly was always more of a diagnostic convention than a clinical reality.

When researchers were finally allowed to study them together, the overlap became impossible to ignore.

What It Actually Looks Like When Both Are Present

The experience of having both ADHD and autism isn't simply the experience of having each one separately. The two conditions interact in ways that can make the combined presentation more complex and harder to recognize than either would be on its own.

Some patterns that come up frequently:

• Masking that is exhausting at a deeper level. Autistic people often learn to camouflage their traits in social situations: mirroring others, scripting conversations, and performing neurotypicality. Adding ADHD to the picture means doing that effortful masking while also managing attention dysregulation, impulsivity, and working memory difficulties. The cognitive load is significant, and burnout tends to be more severe.

• Sensory overwhelm plus attention dysregulation. ADHD already makes it hard to filter out irrelevant stimuli. When autistic sensory sensitivities are also present, environments that others find manageable, such as a busy office, a loud restaurant, or a crowded classroom, can become genuinely difficult to function in.

• Hyperfocus that looks like special interests, and special interests that look like hyperfocus. Both conditions involve the capacity for intense, sustained focus on engaging or meaningful things. Clinicians who are only looking for one condition can misattribute this trait to whichever diagnosis they already have in mind.

• Social difficulties with different roots. ADHD can create social friction through impulsivity, interrupting, or difficulty tracking conversations. Autism creates social differences through distinct processing of social cues and communication. When both are present, the social picture is layered, and addressing only one piece rarely resolves the whole.

• Anxiety as a near-constant companion. Anxiety is common in both ADHD and autism independently. When both are present, the anxiety often runs deeper, frequently rooted in years of not understanding why things that seem easy for others are so hard, and in the effort required to navigate a world that wasn't designed for how your brain works.

Why One Diagnosis Often Gets Missed

There are a few reasons the second diagnosis tends to get lost.

ADHD is often diagnosed first, particularly in childhood, because hyperactivity and impulsivity are visible and disruptive in classroom settings. Autism traits, especially in kids who are verbal, intellectually capable, and have learned to mask, are easier to overlook. Parents and teachers may notice that a child is quirky, rigid, or socially awkward, but if the ADHD explanation is already on the table, the deeper pattern may not get investigated.

The reverse also happens. Some people receive an autism diagnosis, and the attention and executive function difficulties get attributed to autism without evaluating whether ADHD is also independently present. That distinction matters for treatment. ADHD responds well to specific interventions, including medication, that aren't part of autism treatment planning.

And for adults who are self-identifying after a lifetime of muddling through, both conditions may have gone entirely unnoticed. The AuDHD presentation in adults who have spent decades developing compensatory strategies can be subtle and complex, exactly the kind of picture that requires a thorough neuropsychological evaluation to untangle.

What a Thorough Evaluation Looks Like

Identifying both ADHD and autism accurately requires more than a checklist or a brief clinical interview. It requires a neuropsychological evaluation that assesses attention, executive function, processing speed, and working memory alongside the social communication, sensory, and behavioral patterns associated with autism.

At Clary Clinic, we evaluate the full picture, not just the presenting complaint. That means if you come in asking about ADHD and your profile points toward autism as well, we'll say so. And if you come in asking about autism and the testing reveals that ADHD is also part of what's going on, that will be in your report.

We use the MIGDAS-2 as part of our autism evaluations, a sensory-based, qualitative assessment that is particularly well-suited to adults and to presentations that don't fit the textbook description. Combined with comprehensive neuropsychological testing, it gives us a much fuller picture than either alone would provide.

We see one patient per day; no referral is required, and we typically schedule within about 30 days of intake.

If you've been carrying an explanation that has never quite fit, or carrying no explanation at all, a comprehensive evaluation can change that.

Call us at (320) 247-4068 or visit claryclinic.com to get started.