AuDHD: What It Means to Have Both Autism and ADHD

Until relatively recently, you could not officially be diagnosed with both autism and ADHD at the same time. The DSM, the diagnostic manual used by clinicians in Australia and internationally, explicitly excluded the dual diagnosis until its fifth edition in 2013. Before that, if you showed up with both sets of traits, clinicians had to choose. Many chose wrong. Many still do.

The term AuDHD, used informally within the neurodiversity community to describe the co-occurrence of autism and ADHD, has become significantly more visible in recent years, particularly among people who discovered their combined diagnosis as adults or teenagers. It describes something real: a profile that is not just 'autism plus ADHD' but a genuinely distinct experience that comes from the two conditions interacting.

How common is it?

More common than most people realise. Research consistently finds that between 50 and 70 percent of autistic people also meet criteria for ADHD, and between 20 and 50 percent of people with ADHD also meet criteria for autism. These numbers vary depending on the study and the diagnostic tools used, but the direction is clear: the overlap is not a coincidence or a diagnostic error. There is a genuine neurological relationship between the two conditions.

In Australia, as in most countries, the clinical recognition of this co-occurrence is improving but uneven. Some paediatricians and psychologists assess routinely for both. Others still diagnose one and miss the other. If your child has been diagnosed with one and you suspect the other is also present, it is completely reasonable to request a more comprehensive assessment.

What makes AuDHD different from either alone

Autism and ADHD share some features, difficulties with executive function, emotional regulation, social connection, but they also pull in opposite directions in some important ways. This is where the AuDHD experience gets genuinely complicated.

Autism tends toward predictability, routine, and deep focus on specific interests. ADHD tends toward novelty-seeking, impulsivity, and difficulty sustaining attention on things that are not intrinsically motivating. In a person with both, these drives can create internal conflicts that are exhausting to manage: wanting routine but also craving stimulation. Being able to hyperfocus on a special interest but unable to start a task that requires effort. Needing things to be consistent but also quickly bored when they are.

What AuDHD looks like in children

Because the two profiles interact and sometimes mask each other, AuDHD can look like neither, or like something else entirely. Children with AuDHD are frequently misdiagnosed with anxiety disorders, oppositional defiant disorder, or simply described as 'complex' or 'difficult to place.'

One pattern I see regularly in classrooms is the AuDHD student who knows exactly what they are supposed to do, can articulate the rules, the expectations, the consequences, and then does the opposite anyway. This is not defiance for the sake of defiance. It is the impulsivity of ADHD overriding the compliance drive of autism, and both of those things being real in the same moment.

Why diagnosis often misses one or both

ADHD can mask autism. The social impulsivity of ADHD can look like social effort, making it harder to see the social processing differences of autism underneath. Autism can mask ADHD. The rigid routines and rule-following of autism can create the appearance of organisation and attention that hides the ADHD-driven chaos underneath. And both can mask each other in assessment settings, where the novelty of the assessment itself can temporarily boost ADHD attention, or where a child is masking their autism hard enough that neither appears clearly.

This is why comprehensive assessment by a clinician who is specifically looking for both, and who is doing so across multiple settings, with input from both school and home, is important. A half-hour observation in a clinical office will often miss one or both.

What this means for support at school

Schools that understand only autism or only ADHD will often apply strategies that work for one and inadvertently make the other harder. Rigid routines and predictability help the autistic profile but may feel suffocating to the ADHD profile. More flexibility and movement may help the ADHD profile but increase anxiety for the autistic profile. Good support for an AuDHD student requires understanding the interaction, not just the individual diagnoses.

Resources and community in Australia

The AuDHD community in Australia is active and growing, particularly online. There are parent groups, adult communities, and an increasing number of clinicians who specialise in the combined profile. If your child has been diagnosed with one condition and you are wondering about the other, ask for a comprehensive review, it is a completely legitimate request and may significantly change the support picture.

And if your child has already been diagnosed with both: you are not navigating a more complicated version of neurodiversity. You are navigating something specific, something real, and something that with the right understanding can be supported well.