TL;DR
AuDHD is the informal term for having both ADHD and autism. 50–70% of autistic adults also have ADHD. The symptoms can contradict each other — need for stimulation vs. need for predictability — and require an assessment that catches both conditions.
Some people describe it as having one foot on the accelerator and one on the brake. One part of the brain seeks stimulation, novelty, and movement. Another part demands predictability, routine, and calm. The inner conflict is not laziness or poor willpower. It is neurology. And it has a name: AuDHD.
AuDHD is the informal term for having both ADHD and autism. It is not an official diagnosis, but a concept that captures a clinical reality that research overlooked for decades. In their review, Rommelse et al. (2010, European Child & Adolescent Psychiatry) found that the two conditions co-occur in 30–80% of clinical populations. Conversely, a significant proportion of the ADHD population has autistic traits that were never identified.
Why are we talking about it now?
Until ICD-10, it was formally prohibited to make both diagnoses in the same person. Autism was considered an exclusionary diagnosis for ADHD. In practice, this meant thousands of people received only half the picture. With ICD-11, that has changed. WHO now recognizes that autism (6A02) and ADHD (6A05) can be diagnosed concurrently. DSM-5 has already permitted this since 2013.
Denmark transitions to ICD-11 in 2027. But the clinical reality is already here. Many Danish clinics, including Alethia, work according to the DSM-5 principle of concurrent diagnosis. The Danish Health Authority has in its most recent ADHD guidelines recommended broad differential diagnostics, including screening for autism.
Symptoms that look alike
ADHD and autism share a surprising number of surface symptoms. That is one of the reasons one condition so often masks the other. But although the symptoms look alike, the underlying mechanisms are different.
| Symptom | ADHD mechanism | Autism mechanism |
|---|---|---|
| Social difficulty | Inattention to social cues, impulsive interrupting | Structural communication deficit, difficulty reading implicit cues |
| Executive dysfunction | Activation, focus, effort, working memory | Cognitive inflexibility, planning, set-shifting |
| Sensory sensitivity | Stimulus-seeking or avoidance | Hyper- or hyporeactivity (ICD-11 criterion) |
| Emotional dysregulation | Reactive, quick to trigger, quick to resolve | Meltdowns from overload, slower recovery |
| Hyperfocus / restricted interests | Interest-driven, shifts between topics | Deep, sustained, narrow, stable over time |
The table illustrates why a superficial screening can easily confuse one with the other. Both cause social difficulties, but for entirely different reasons. Both affect executive functions, but in different ways. That is precisely why a thorough assessment is essential.
The key differences
Although the symptoms overlap, there are patterns that help distinguish the two conditions. They require clinical experience to evaluate, but they are real and consistent in the research.
The clearest difference is social. People with ADHD are typically socially motivated but clumsy in execution: they interrupt, forget names, and lose the thread mid-conversation. People with autism experience a more fundamental difficulty with social communication, reading facial expressions, understanding irony, navigating unspoken social rules. The difference is not whether you want the social, but what makes it hard. Interest patterns follow a similar split: ADHD hyperfocus is intense but fleeting, shifting from week to week. Autistic restricted interests are deep, narrow, and stable over months or years. Many with AuDHD have both: shifting hyperfocus and a stable core interest.
Sensorially, the two conditions experience the world very differently. ADHD often creates a tendency to seek stimulation: loud music, strong flavors, need for movement. Autism typically produces specific, consistent sensitivities: particular sounds, textures, or lighting conditions that are consistently uncomfortable. Sensory hyper- and hyporeactivity is an ICD-11 criterion for autism and is often one of the earliest signs in an assessment.
Repetitive behavior can look the same from the outside but fulfills different needs. ADHD restlessness is motor-driven: rocking the chair, drumming fingers, difficulty sitting still. Autistic stimming serves a regulatory function, helping manage sensory overload or emotional intensity.
Finally, there is the developmental trajectory. ADHD hyperactivity typically diminishes with age and is replaced by inner restlessness. Autistic traits are stable over time, but can be masked by learned compensation strategies, especially in women. The symptoms do not disappear, but they become invisible, which is one of the reasons autism in adults is so often missed.
When one diagnosis hides the other
The most overlooked aspect of AuDHD is how the two conditions mask each other. ADHD can compensate for autism's rigidity by adding spontaneity and social energy. Autism's structure and routines can compensate for the ADHD brain's chaos. The result is a person who looks neither typically ADHD nor typically autistic, but who lives with an impairment more severe than the sum of its parts.
That is why executive dysfunction in people with both conditions is often more pronounced than in either ADHD or autism alone. The brain struggles with opposing needs: stimulation and predictability, flexibility and structure, social contact and recovery. It takes enormous amounts of cognitive energy to navigate this conflict, and many experience chronic exhaustion that neither ADHD nor autism treatment alone can resolve.
When should you suspect both?
There is no single test that can determine whether you have AuDHD. But there are patterns that should raise attention in a clinical assessment. You can start with our free autism screening (RAADS-R) to see if an assessment may be relevant:
- Social difficulties that sometimes improve with motivation (ADHD pattern), but other times persist regardless of effort (autism pattern)
- Attention problems and narrow, persistent interests, both present from childhood
- Executive dysfunction more severe than expected from either ADHD or autism alone
- A sense of being different that neither ADHD nor autism alone can explain
- Previous treatment for ADHD that only partially helped because the autistic elements were not addressed (or vice versa)
How do we assess AuDHD at Alethia?
We never assume it is only one thing. Our assessment process is designed to catch both conditions, regardless of which suspicion you start with.
The first session is a broad clinical interview with systematic screening across all diagnostic categories (F0-F9 in ICD-10). That means we don't only look for what you came in for. We look for everything that could explain your difficulties.
For ADHD, we use DIVA-5, the diagnostic interview recommended by the Danish Health Authority (see our ADHD assessment process). For autism, we use ADOS-2 (observation) and AAA (Anamnestic Autism Assessment) in our autism assessment. In addition, we use screening instruments like RAADS-R, CAT-Q (camouflaging), AQ and EQ to form a complete picture.
The crucial point is that we don't stop at the first diagnosis. If autism features appear during an ADHD assessment, we supplement with the autism battery. If ADHD signs show during an autism assessment, we add DIVA-5. Both assessments are completed in full, because a half-finished assessment is worse than no assessment at all.
At Alethia, clinical psychologists and psychiatrists work under one roof. The psychologists conduct the assessment, and the psychiatrists can initiate medication immediately after diagnosis, if relevant.
Comorbidity is the rule, not the exception
Large epidemiological studies, including Kessler et al. (2006, Archives of General Psychiatry), consistently show that only a minority of adults with ADHD have ADHD alone. For most, 70–80%, at least one other diagnosis comes along. Anxiety, depression, sleep disorders, and autism are the most common. This is one of the reasons an isolated ADHD screening that doesn't look more broadly risks missing what changes the treatment plan.
For people with AuDHD, this is particularly important. Medical treatment of ADHD (e.g. methylphenidate or lisdexamfetamine) can improve attention and impulsivity, but it does not change the autistic difficulties. Conversely, structure and routines that help with autism's need for predictability can feel suffocating to the ADHD brain. A treatment plan that only addresses one diagnosis risks worsening the other.
What does an AuDHD assessment cost?
A combined autism and ADHD assessment with medication initiation costs approximately 17,800 DKK across 6 or more sessions. You pay per session over several weeks. If you already have an ADHD assessment underway with us and autism is suspected, we expand the process. There is no need to start over.
We can typically offer a first appointment within 2 to 4 weeks. You can book directly without a referral.
Do you recognize yourself?
Book your first clinical interview. We screen for both conditions from the start.
Frequently asked questions
AuDHD is an informal but widely used term for people who have both ADHD and autism simultaneously. It is not an official diagnosis, but a collective term that has grown as research and diagnostic systems now recognize that the two conditions can coexist. In ICD-11, both diagnoses can be made concurrently (6A02 + 6A05), which was not possible under ICD-10.
Yes. Meta-analyses show that 50–70% of autistic adults also meet the criteria for ADHD (Lai et al., 2019, The Lancet Psychiatry). Conversely, 20–50% of adults with ADHD have significant autistic traits (Antshel & Russo, 2019). DSM-5 already permits concurrent diagnosis, and ICD-11 follows the same principle. Denmark transitions to ICD-11 in 2027, but many clinics already work according to the newer guidelines.
At Alethia, we systematically screen for both conditions. Our ADHD assessment with DIVA-5 includes a broad screening (F0-F9) that can catch autism features. Conversely, our autism assessment always includes screening for ADHD. If suspicion of the other condition arises during the process, we supplement with the relevant tools (e.g. RAADS-R, CAT-Q, AQ and EQ for autism, or DIVA-5 for ADHD). Both assessments are completed so we don't stop at the first diagnosis.
A combined autism and ADHD assessment with medication initiation costs approximately 17,800 DKK across 6 or more sessions. You pay per session over several weeks. We can typically offer a first appointment within 2 to 4 weeks. You can book directly without a referral.