The Intimate Link Between ADHD and Autism

You've probably heard about the rising rates of both autism and attention deficit hyperactivity disorder (ADHD) in adults. Is there any truth to all the talk about an overlap between the two? You can probably tell by the title that, yes, there is! 

Topics discussed also include:

• The three presentations or subtypes of ADHD
• Differences between ADHD in kids versus ADHD in adults
• Some of the main differences and similarities between "ADHDers" and autistic folks
• Why some experts think that ADHD is a form of autism

If you'd like to know more about topics discussed in this episode, check out:

"Heritability of Attention-Deficit Hyperactivity Disorder in Adults" by Isabell Brikell et al.

"Overlap Between Autism Spectrum Disorders and Attention Deficit Hyperactivity Disorder: Searching for Distinctive/Common Clinical Features" by Francesco Craig et al.

"The Impact of the Comorbidity of ASD and ADHD on Social Impairment" by Christina Harkins et al.

"Co-occurrence of ASD and ADHD Traits in an Adult Population" by Maria Panagiotidi et al.

"Trait-Based Dimensions Discriminating Adults With Attention Deficit Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD), and Co-occurring ADHD/ASD" by Artemios Pehlivanidis et al.

Episode intro and outro music: "Sigma" by Crystal Shards

Theme music: "Everything Feels New" by Evgeny Bardyuzha.

All episodes written and produced by Kristen Hovet.

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The views, opinions, and experiences shared by guests on this podcast are their own and do not necessarily reflect those of the host or production team. The content is intended for informational purposes only and should not be taken as medical or professional advice. Please consult with a qualified healthcare provider before making any decisions related to your health, fitness, or wellness.

Transcript

Kristen Hovet  
Today I'm responding to a request from a listener to have a whole episode about autism and ADHD. Since I spoke about substance use and autism last week, with some info about ADHD as well, I thought it was timely to talk about this subject this week. To reiterate something I mentioned in the last episode, I have been assessed for ADHD and don't have it, so I can't speak about ADHD from personal experience, but it does run in my family. This is apparently quite common for autistic folks. We can look at our immediate family members and relatives, and usually see a significant smattering of autism, ADHD, or co-occurring autism and ADHD related traits, whether these folks are diagnosed or not. As many of you know, who've been listening to this podcast for a while, this season of The Other Autism is dedicated to my late little brother, Jamie, who passed away in December, three months ago today. Long before I was diagnosed as autistic, Jamie was diagnosed with ADHD as a child. And I watched the dramatic change in him between the time before his diagnosis, and after he went on ADHD meds. When I say dramatic, I mean, it was like living with an entirely different person. I can only imagine the positive changes in his learning, concentration, and his own sense of himself. I won't go into more detail than that, but I can say that in addition to Jamie and myself, there are other members of our family with suspected autism and or ADHD. In some cases, these are relatives who have long since passed away, but we can look back and go yep, the traits are strong with that one, and that one, and that one. Of course, there are some autistic folks or ADHDers, who are the only ones in their family with autistic or ADHD traits. Or maybe they aren't close with their families or blood relatives for one reason or another, so they don't have this information. That's totally okay. But definitely the majority of us can see neurodivergent traits very strongly in our families. Once you know what those traits are, once you see them, you can't unsee them. I think I need some music.

Kristen Hovet  
So I've talked a lot about autism on this podcast, and I plan to keep talking a lot about it. So I'm gonna start by spending some time talking about ADHD, and how it presents specifically in adults. I'm doing this because just as there's been an explosion of adults getting diagnosed as autistic, there's been an explosion of adults getting diagnosed with ADHD for the very first time, too. ADHD, like autism, is a neurodevelopmental condition or difference, meaning that you are born with it. You can't suddenly become ADHD or autistic. You were always this way. You can indeed, however, slip through diagnostic cracks, especially if you're female or born female. Both autism and ADHD have been historically thought of as primarily male conditions. And both can present a bit differently in girls and women. So girls and women are much more likely to experience significant delays in diagnoses of neurodivergent identities. 

Kristen Hovet  
ADHD is the most common neurodevelopmental disorder, with recent estimates putting prevalence of ADHD at approximately 5% of the adult global population. But the prevalence rate might be quite a bit higher due to the number of people still assumed to be undiagnosed. Those with ADHD experience difficulties with attentiveness, and or hyperactivity, and or impulsivity. The Diagnostic and Statistical Manual of Mental Disorders, fifth edition, aka the DSM-5, describes three presentations or types of ADHD, and those are primarily inattentive, primarily hyperactive impulsive, and a combined type, meaning a combination of inattentive and hyperactive slash impulsive. For our listeners in countries or locations that use the International Classification of Diseases, 10th revision, aka the ICD-10, ADHD corresponds most closely with hyperkinetic disorder. While once thought to be a condition that's eventually outgrown, at least 65% of those who received ADHD diagnoses in childhood go on to retain full diagnoses or considerable symptoms or traits at an impairing level throughout their entire adult lives. From what I've read, this is likely much higher than 65% since there's a lack of evidence based symptom descriptions that apply to adults, making this prevalence especially challenging to gauge. For example, while children with ADHD are often physically very active and are described as having challenges sitting still or paying attention, adults with ADHD may primarily present with distractibility and difficulties maintaining goal oriented or future oriented behaviors. In other words, they have trouble looking ahead and setting and meeting future focused goals. They may be described by others as living purely in the moment or flying by the seat of their pants. They may no longer present or appear as hyperactive. 

Kristen Hovet  
A huge, massive, ever growing body of research shows a very clear link between ADHD and autism. There's significant co-occurrence between the two, both on the individual level and within families. Did you know that the fourth edition of the DSM, aka DSM-4, prohibited a co-diagnosis of ADHD and autism? Well, it did. And I have oft wondered to myself, if this has had a hand in the delayed societal level recognition of the co-occurrence of these two identities. I'm of the mind to believe so since this kind of blunder or oversight in the diagnostic literature can hamper some research initiatives, especially those looking to differentiate between the diagnoses. With the DSM-5, however, changes were made to allow for a co-diagnosis of the two identities, in other words, making them no longer mutually exclusive. These changes were made to the DSM-5 based on high quality and extensive epidemiological, clinical, and neuroimaging findings. Since then, massive amounts of research have looked into the overlap and co-occurrence of ADHD and autism, on the molecular levels, behavioral levels, social levels, all the levels. It's exciting stuff, for sure. 

Kristen Hovet  
Also, when people say all this talk about ADHD and autism being a trend, yada, yada, yada, my response is, give me a break. I don't want to hear it. I don't have patience or time for it. If you're suspicious about ADHD and autism and adults or whatever, check out the links in the show notes to see where I got my information and where you, too, can look at the details and trace the fascinating history of all of these findings, and more. That's literally all the time I'm going to give to the naysayers on that. 

Kristen Hovet  
Did you know that ADHD is the second most common co-occurring condition in autistic folks? The most common, from what I've read, is anxiety and anxiety disorders. Anxiety disorders include generalized anxiety disorder, panic disorder, social anxiety disorder, phobia related disorders, and post traumatic stress disorder, shortened to PTSD. Interestingly, ADHD and anxiety disorders are often co-occurring, too. One quarter to 1/3 of those with ADHD also have an anxiety disorder. There are just so many overlaps going on here. My brain's in hardcore Venn diagram mode today. 

Kristen Hovet  
Research has shown that autistic individuals and ADHDers share many structural brain differences compared to their non autistic or non ADHD peers. And both autism and ADHD are highly heritable with genetic factors accounting for approximately 70 to 80% of the phenotypic variance of each condition. What does phenotypic mean? Phenotype or phenotypic refers to the observable characteristics of a person that result from the interaction of their genetic makeup and their environment. I also want to clarify what is meant by environment. Here environment doesn't just mean like environmental in reference to the natural world, but basically everything in the person's surroundings. Their household, their family life, their diet, the things they watch on TV, the quality of their schooling, and on and on and on, which does actually include environmental influences, but just to note that it's not just that. The dictionary definition of environment, in this sense, includes the surroundings or conditions in which a person, animal, or plant lives or operates. 

Kristen Hovet  
A study of ADHD and autistic traits in adults found that individuals with one or the other diagnosis experienced extensive executive function-based differences when compared to adults without either diagnosis. One interesting finding from this study led by someone named Maria, I'm gonna have to look that last name up. I'm gonna put it in my phone and see if that helps. Let's see here. Doo, doo, dooo! Sure...

Google  
Maria Panagiotidi. Maria Panagiotidis.

Kristen Hovet  
Pana-gia-tidis. Ha, okay. So one interesting finding from this study, led by Maria Panagiotidis, or in Greek... 

Google  
Maria Panagiotidi! 

Kristen Hovet  
...was that high attention to detail appears to be a trait that's specific to autism and not ADHD. This means that autistic individuals and autistic individuals with ADHD often display high attention to detail, but this trait is not associated with those who have ADHD alone. 

Kristen Hovet  
A study led by Artemios hmmm...

Google  
Artemios Pehlivanidis. 

Kristen Hovet  
Peh-li-vanidis...

Google  
Artemios Pehlivanidis! 

Kristen Hovet  
Well it sounds better that way, but I don't know how to say it. Okay. A study led by Artemios Pehlivanidis found that around 16% of their adult study participants with ADHD had enough autistic traits to also qualify for an autism diagnosis, while 1/3 of their adult autistic participants had enough ADHD traits to also qualify for an ADHD diagnosis. Other research in younger populations showed that 18 to 50% of children with first diagnoses of ADHD also qualify for an autism diagnosis, while 40 to 70% of children with first diagnoses of autism also qualify for an ADHD diagnosis. 

Kristen Hovet  
Interestingly, some researchers have proposed that ADHD should fall under the autism umbrella as one flavor or variety of level one autism, given the level of overlap of traits between the two. Anecdotally, I know many diagnosed with both say something similar, in that they can't tell where their ADHD ends and their autism begins or vice versa. Research showing extensive genetic overlaps between the two also provides a strong argument for this formulation of ADHD as a type of autism. However, the majority of research, by my interpretation, shows the clear need to keep ADHD and autism separate or distinct. For example, researchers note that those with dual diagnoses of ADHD and autism typically experience more challenges than those with the separate diagnoses. Those with ADHD alone or ADHD plus autism experience more externalizing behaviors, while those with autism diagnosis alone are more likely to display internalizing behaviors. Externalizing behaviors include acting out vocally or physically with movements and actions, aggression, or even being rough with objects. Externalizing behaviors are directed at others or objects around oneself and are typically observable to others. Internalizing behaviors, on the other hand, are directed towards the self and are typically not observable or obvious to others. Internalizing behaviors include depression, social withdrawal, loneliness, nervousness, negative self talk or thinking, and so on. 

Kristen Hovet  
Around half of children with ADHD have sensory processing differences, while nearly all autistic children have sensory processing differences. To me personally, this is one major reason to keep the two diagnoses separate and distinct. Of course, I think I'm biased as someone without an ADHD diagnosis, who would classify my sensory differences as the main characteristics of my autism. The second main set of characteristics, for me personally, is probably a tie between the depth of focus and interest levels in certain topics that I have, as well as the depth of my emotions, and just how overwhelming emotional states can be, whether they be positive or negative, or some super confusing combination of both. 

Kristen Hovet  
From my reading, I also think the executive function differences exhibited by those with ADHD alone, and by those who are autistic alone, necessitates separate diagnoses. Those with sole autism diagnosis tend to have hyper focus and, while they can appear inattentive at times, this apparent inattentiveness can usually be chalked up to challenges with task switching, or switching focus from one thing to another. Those with sole ADHD diagnosis have challenges with focusing in general and, at least from what I've read, don't typically have an issue with task switching. If anything, they switch too quickly or too often from one thing to the next and have trouble focusing deeply for long periods of time. Also, those ADHDers with the hyperactive slash impulsive presentation or subtype experience movement differences that are not usually associated with autism. 

Kristen Hovet  
Some research has indicated that those with dual autism ADHD diagnosis experience more challenges with adaptive functioning than those with sole diagnoses. What is adaptive functioning? Adaptive functioning refers to daily living skills or tasks of day to day life, such as personal care and grooming, managing a household, maintaining finances, following schedules, staying safe and healthy, acquiring food and cooking for oneself, and so on. Adaptive functioning includes getting along well with others and obeying societal laws and expectations. Those with dual diagnosis may also experience more meltdowns than autistic individuals without ADHD. I could keep going on about the similarities and differences here, but I think I'll only mention two more. 

Kristen Hovet  
The second to last thing I want to mention is that autistic and ADHD individuals share social challenges and differences in forming and keeping friendships when compared to neurotypicals. Both autistic and ADHD kids are often bullied and tend to focus on just a few friends. While both share so-called social challenges or differences, I think the social challenges are there for very different reasons. ADHDers can experience challenges reading neurotypical social cues because of differences in their attention or focus level, while neurotypical social cues do not intuitively make sense to autistic folks, and or autistic folks actively find some neurotypical social behaviors unwanted or uninteresting, for example, small talk. So they might just excuse themselves and therefore appear, I don't know, antisocial. So the social behaviors may appear similar between autistic folks and ADHDers, but they're coming from very different places. The similarity, of course, is in there standing out from neurotypical norms. 

Kristen Hovet  
Lastly, some research has indicated that those with the dual diagnosis report lower IQ on average than those with sole diagnoses. Although, I think it's safe to say that more work is needed to clarify this particular point. It's a weird one. I also take issue with IQ reporting in general because it misses other types of intelligence, or places a certain form of intelligence on top of some imaginary, weird hierarchy. Well, anecdotally, I can tell you that some folks I've met with a dual diagnosis qualify as artistic geniuses who may not show up highly on so-called intelligence tests, but would blow everyone else out of the water on many other tests, were they to exist. Some of them do, I know, but they're not often used, unfortunately, in the research. No one can touch these folks in terms of their ability to imagine new worlds, new realms, new ways forward in the ways of artistry, and design, and similar focuses. All that to say, all told, there really are enough differences to warrant keeping the two separate, distinct identities of ADHD and autism. I think this also allows for proper attention to be given to those with the dual diagnosis of ADHD plus autism. 

Kristen Hovet  
I'd love to speak with someone with the dual diagnosis. I don't think I've been in touch with anyone with both. I'd have to look back and see. I'd actually really love to interview someone with the dual diagnosis so that we can get a sense of your day to day life, and what types of strategies work for you. And yeah, I just want to hear your story. Before I say goodbye, I have a quick announcement. The Other Autism Podcast is now on Instagram. Yay! Follow us at otherautismpodcast on Instagram. Why did I say us? Follow us? I'm one person. Maybe it refers to Toby and I, Toby the cat and I. Follow us at otherautismpodcast on Instagram. I've started answering listener questions, like shorter ones, via Instagram reels. So be sure to check it out. Again, it's otherautismpodcast, all one word, on Instagram. The link's also in the show notes. I look forward to seeing you there. Well, that's all I have for you today.

Kristen Hovet  
Thank you so much for being here. Until next time, bye.