ADHD Primer Part 3 – Autism and ADHD, aka AuDHD

TL,DR: If a person has sufficient traits of Autism and sufficient traits of ADHD, then that person should be diagnosed with Autism and ADHD Comboridity. “Co-morbid” is the medical term for co-occuring for the same person. The question, though, is how common is a comorbid diagnosis in society, and how common should it be?

Here are links to Part 1 and Part 2:

Understanding Autism – A Very Quick Primer

Before we can look at the overlap of Autistic and ADHD people, we need a quick and dirty primer on Autism.

Much like ADHD, Autism is a neurological divergence from the neurotypical brain. Autism’s inclusion to the American DSM (Diagnostics and Statistical Manual of Mental Illnesses) was, like ADHD, a mixed bag. While it helped many medical professionals gain a better awareness that Autism was a thing to factor into their diagnosis and understanding of people, it changed how medical professionals, and thus how public perception, categorise Autism. The inclusion in the DSM erroneously re-categorised Autism from a neurological condition to a mental illness.

Autism is not a mental illness in and of itself. Like ADHD, Autistic people can experience mental illness. Often this is a result of external problems, such as societal stigma, exclusion and traits that are not well managed. Autism is not a disability in and of itself. Like ADHD, Autism can be disabling. Autism does not mean the person has an intellectual disability. Like all people, Autistic people can have a comorbid intellectual disability.

Much like ADHD, Autism is poorly defined in the two basic diagnostic manuals, the American DSM and World Health Organisation’s ICD. In simple terms, the first criteria for diagnosis (according to both the DSM and ICD) approximately says “has difficulties with being social”. The latest Text Revision of the DSM 5 is particularly heinous in stopping right there – no other factor is considered. The ICD has a secondary test, which is checking to see if the person has classic odd behaviours in patterns and or special interests. The ICD prioritises the social difficulties over the other symptoms – the “has no friends” false stereotype.

I have literally had a GP tell me the person I would like assessed can’t be Autistic because they have friends. Firstly, are those friends also Autistic? Secondly, for Autistic people to survive this society, many of them learn to mask. Masking is where you try to give other people the social signals that they would expect from a neurotypical person – it is exhausting. If you find being around most people is tiring, then you are likely masking. Thirdly, the reason the name was changed from Autism to Autism Spectrum Disorder was to highlight that there are a range of traits that an Autistic person may have, in different strengths and showing in different ways. Social difference is just one of those traits, not the only trait. To emphasise, you can be Autistic and have friends.

Ok, I think that is enough of a quick Primer on Autism.

Prevalence is the medical term for indicating how likely a thing is to be found in a random, or specific, group of people. Interestingly, any “condition” that is considered to be higher than 1% of the population is considered to be just a part of being human. For example, the prevalence of Left Hand Dominance is between 9-11%, thus being a Leftie is both common and a normal part of being human, rather than a disorder. Being a Leftie can be disabling in some circumstances, but it is not a disability in and of itself.

Unlike being Left Hand Dominant, assessing Autism and ADHD is unexpectedly challenging. Part of this is the poor definitions given for each condition. Another issue is whether the government agrees that ADHD and or Autism is an actual condition or not; and if so, how is that defined, tested and treated. This leads us to some wildly fluctuating international numbers for both Autism and ADHD.

Let us focus more specifically on Australia. 

Deloitte estimated that the range of prevalence of ADHD in Australia is between 1.8% to 5.8%. Deloitte explains that accurate estimates for ADHD in Australia are difficult due to shifting criteria, poor definition and variable access to diagnosisticans. Deloitte also points out the contradiction of various officials claiming that ADHD is both over and under diagnosed. Surely both can’t be right?

The same story exists for Autism. Australian prevalence estimates for Autism vary widely, from 0.67% (1) to 4.8% (2) in youths alone. Autism and ADHD are brain types you are born with, so you don’t “grow out of” them. 

These estimates are so varied in range, they become untrustworthy. Even so, the rates are clearly higher than the 1%, so much like being left-handed, both Autism and ADHD are just a part of being human.

Back to our first question – what is the comorbid prevalence? That is, how many Autistic people have comorbid ADHD, and how many ADHDers are Autistic?

We don’t actually know.

Autism Spectrum Australia (3), in regards to Autism and ADHD Comorbidity wrote “Estimates of co-occurring ASD+ADHD vary widely. Generally, it is considered that the majority of individuals with autism also have ADHD symptoms. However, in some studies the proportion of children with autism who also have clinical symptoms of ADHD is reported to be as low as 14% while other studies report it to be up to 85%. Similarly, clinically elevated levels of autism symptoms have been noted in 18% to 67% of children with ADHD.”

Those are some mighty big error bars. In any hard science field, these results would be laughed at. 

Science has failed us. 

If we can’t trust the existing science, then what is my clinical experience?

Out of all my clients that I have recommended seeking assessment, those clients who have persisted through waitlists; additional referrals; expense; and have been assessed by a professional who has the authority and expertise to provide a diagnosis – all of them have been confirmed to have ADHD and/or Autism. This indicates that my ability to assess Autism and ADHD is very accurate. I am not claiming to be foolproof though, so take the following speculation with a pinch of salt.

My experience matches what Autism Spectrum Australia found. In my opinion, all of my Autistic clients show sufficient traits to qualify for an ADHD diagnosis, and most would benefit from access to ADHD medication. In my experience, all of my ADHD clients show sufficient Autism traits to qualify for an Autism Diagnosis.

Yet very few of my clients have a dual Autism and ADHD Comorbidity diagnosis.

It is important to understand that the struggle to get just one diagnosis is quite hard. To get the second diagnosis is even more difficult. That might be hard to understand if you have not had to navigate the gauntlet of gaining a diagnosis for either one. It is ridiculously hard, but explaining how hard is beyond the scope of this. If you only have the resources to pursue one diagnosis – either Autism or ADHD –  my common recommendation is to get the ADHD diagnosis. An ADHD diagnosis will get you access to restricted medication that helps both conditions – don’t fall for the erroneous opinion that “you can’t medicate Autism”.

In my experience, it isn’t just an Autism and ADHD Comorbidity… Autistic people and ADHDers are the same people, and so share the same experiences. With two camps flying under different banners, this has led to both camps describing these specific similar experiences with different language and flavour, falsely attributing the traits/behaviour/experience as unique to their category.

This, combined with very different diagnostic criteria, has erroneously led to the historical belief that Autism and ADHD are so unrelated that it is only possible to be diagnosed with one condition. In Australia, this error has led to the role of diagnosing people for ADHD and Autism to generally be done by two separate systems and professionals, adding to the struggle to get properly assessed, diagnosed, and where relevant, treated.

What of the traits that are not unique? Surely that is where this shows that Autism and ADHD are not the same, right? For example, Autistic people love pattern and order, while ADHD love chaos – checkmate Joshua, checkmate.

Some Autistic people love pattern and order. They find the patterns comforting, the efficient elegance and find order cheaper to maintain. Some Autistic people are incredibly messy, because they see that there is no true system, and trying to maintain any kind of system is very fatiguing. Some ADHDers can’t maintain a system to save their life, while others like a very simple black and white system because it is easier to maintain and this way they don’t lose their keys all of the time. Hopefully you have noticed that I have described the same behaviour range twice, just with different language. Remember, spectrum means that traits exist on a range.

In my opinion, the Venn Diagram of Autism and ADHD is not quite a circle, but it is darn close. Perhaps it is a circle.

One might ask if there is such a high overlap of Autism and ADHD Comorbidity, is there really a difference? Personally, I speculate that ADHD may actually be a trait of Autism, and hope we will see increased understanding of the overlap within the scientific and health communities in the near future.

Venn diagram offering an overlap of Autism and ADHD, OR just Autism/ADHD called AuDHD
Venn Diagrams – Are Autism and ADHD separate with Autism and ADHD Comorbidity overlap, or are they the same thing, called AuDHD?


(1) “Autism in Australia”, Australian Government,

(2) “Autism Spectrum Disorder Prevalence in Children Aged 12–13 Years From the Longitudinal Study of Australian Children”, Wiley Online Library,

(3) “Autism and ADHD”, Autism Spectrum Australia,

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