Podcast Episode 39:
ADHD and Dyslexia: Is there a link?

As someone who meets a lot of children with ADHD and a lot of children with dyslexia, I began to notice that a lot of my “ADHD” students have struggles that mimic those of my students with “dyslexia”, and those with “dyslexia” often seemed to exhibit ADHD characteristics, and sometimes children were diagnosed with both.


I was often told all the reasons that dyslexia might cause inattention and all the reasons why ADHD might cause reading struggles, but it wasn’t enough to explain what I was seeing, so I started digging.


If you are a little bit of a research nerd, you’ll find this episode especially fascinating!


Brain scans reveal a link between ADHD and Dyslexia.  Parents of children with dyslexia or with ADHD should understand that there is scientific evidence to watch carefully for the other “disability” if there child has either ADHD or Dyslexia.  And, a differently wired brain does not actually need to be seen as a disability.

Audio version: www.DecodingLearningDifferences.com

This is Decoding Learning Differences with Kimberlynn Lavelle. This episode is ADHD and dyslexia: Is there a link? now this episode I decided to do, because I was interested in the topic. I've noticed that a lot of my students with ADHD and have or dyslexic characteristics, even if it's not identified. And a lot of my students with dyslexia identified have ADHD or ADHD characteristics,

even if it's not identified. So I wanted to know, is there a correlation, is there a connection? What does the research show? So just a quick refresher. ADHD is attention deficit hyperactivity disorder under the current DSM five, which I'm not an expert in, but my understanding is you can have the inattentive type, the hyperactive type or combined. So you don't have to be inattentive to have ADHD.

You don't have to be hyperactive to have ADHD. Although most, from my understanding, very few people get diagnosed with the hyperactive kind, because that would mean that you don't have inattention. You only have hyperactivity, but most of the time the hyper activity would cause some inattention. So most of the time you're either inattentive type without the hyperactivity or the combined.

So those are the two, the three options for ADHD, but there's two that are very, the most common. dyslexia is a difficulty in reading and or spelling caused by a deficit or impairment in phonological processing. That's a loose working definition, different people define it different ways. And we've looked at that in depth previously and there's been a couple of episodes on dyslexia.

So look in the show notes and I'll reference back to those episodes and we go and we go in depth there. So both of these conditions, ADHD and dyslexia both happen depending on where you're reading between 5% and 10% of the population has ADHD. And between five and 10% of the population has dyslexia. Now what's interesting is that they have found that depending again,

on which study, you're looking at 25 to 40% of those with ADHD also have dyslexia and 25 to 40% of those with dyslexia also have ADHD. So there is a stronger correlation for having both than just having one of them. So I was kind of digging into, okay, why, why what's happening now, there are reasons for inattention in dyslexia, besides ADHD.

This is a big one that we've talked about before. Sometimes people with dyslexia will, will be inattentive because they don't understand what's going on. Or their phonological processing is so poor that they are having a really hard time maintaining the amount of mental energy. It requires to listen, understand, redo the assignment. So it leads to, I can't pay attention to this anymore.

My brain cannot pay attention to this anymore. And it's not that it's ADHD. It's that? It's the, the learning disability and this isn't just dyslexia. It's learning disabilities in general can cause inattention, if things are too hard, you know, if they're in a classroom and everybody is doing things way over their understanding, then they can't pay attention to it because they don't have the understanding of what's going on.

It's just too hard to maintain attention when everyone is speaking Greek and you don't speak Greek, like you can't, you can try to pay attention for like 20 minutes and then you're just done for the day. Right? So keep that in mind that there are reasons for inattention, for those with dyslexia, besides ADHD. And there are reasons for reading and spelling struggles in those day,

DHD, besides dyslexia, if you're very inattentive, you aren't necessarily attending to the minute details of whether it's S A I D or S I AD because neither one makes sense to you on why it would be called said, so you just spell it however, or maybe you say S E D cause that makes more sense to you. And you just,

you're not, you're not attending to the tiny details and therefore you're struggling with spelling, or you're struggling with reading, because again, it's so hard to pay attention that you don't get as much practice as the other kids who are able to pay attention for longer. So there are reasons for reading and spelling struggles that don't have anything to do with dyslexia in those with ADHD,

but there is strong evidence for shared genetic and neuro-psychological risk factors that contribute to the dyslexia, ADHD community. I will link the article that I got this from in the notes. There is strong evidence for genetic and neuro-psychological risk factors that contribute to the dyslexia, ADHD community. So there's, they've figured out that there are some genetic predispositions that cause you to have that,

like they both share risk factors for both dyslexia and ADHD are deficits in processing speed and executive functioning. So both ADHD and dyslexia have a weakness in your processing speed, how quickly you process information and in executive functioning, which a lot of times has to do with like organization of tasks and decision-making, and there's a lot to executive functioning. Okay, so Some brain scans were super interesting.

And they found that the amount of overall gray matter in those with ADHD, those with dyslexia, and those that are of the neuro-typical population, they all have about the same amount of gray matter. There's no, no significant differences in the amount of gray matter brain brain matter, right? The actual amount of neurons, so to speak, the actual overall amount is the same.

So the right caudate emerged as a region of statistically significant conjunction between dyslexia and ADHD. So it showed smaller volumes, whether the person had ADHD dyslexia or both ADHD and dyslexia, all of those populations had a reduced amount of gray matter in the right caudate portion of the brain or region of the brain, which does impact what we're talking about,

the executive functioning and the processing speed. So it all lines up. Yeah. So brain scans were showing that, so the role of the caudate in dyslexia remains unclear, but executive functions and procedural learning are two candidate cognitive constructs that may overlap between dyslexia and ADHD. The over the overlap between dyslexia and ADHD in the right caudate might point to impairments in procedural learning and or executive functions that are risk factors for both disorders.

But really big thing to keep in mind is they have to do a lot more research. They are not done with all of their research. They've got more things they're trying to figure out pieces that they're trying to together. One thing that this this study was finding was there, wasn't a whole lot of brain scans done on people who had both ADHD and dyslexia.

Most of the time, if you had dyslexia, if they're doing a study on dyslexia, they want people who only had dyslexia and did not have any other comorbidities, other, any other diagnoses. But the problem is they might be scanning people who do have ADHD and haven't, it hasn't been identified. They also might. Then they also don't have that evidence for these other studies that want to look at the comorbidity,

that the connection between ADHD and dyslexia. So more research, definitely it needs to be done, but all of this, I found very interesting. I wanted to share it with you, a takeaway for you is that if your child has dyslexia or has ADHD has been tested for the other and maybe have them tested by a neuropsychologist rather than the school psychologist,

because they can do a little bit more and get more into the brain function. So that'd be just a thought. Another takeaway is they all have. all brains that were studied, had about the same amount of gray matter. There, the amount in one area was less, which means that there was more in other areas more than the neurotypicals in other parts of the brain.

So those who have dyslexia, those with ADHD, and this is true for other disabilities as well. They are differently wired. They are not deficient. There's nothing wrong with the brain. There's a different wiring of the brain. And we're going to be getting into that a lot in the next couple of weeks, getting into the advantages of dyslexia and the advantages of ADHD.

So another takeaway use their strengths, use the ADHD and dyslexia strengths. And you'll see how to do that, especially in the next couple of episodes where we really get into the advantages of dyslexia and ADHD based on the books by those names. So tell me your stories. Kimberlynn@DecodingLearningDifferences.com. I can't wait to hear from you and I'll talk to you again next week.



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