I'm actually really shocked by these results. This paper is a little bit controversial. I was reading about that going, oh my goodness. We could almost do a run of the study right now with the people who are the sinkloos of this podcast. There's sort of no roadmap on what we're going to struggle with and what we're not. I was wondering where the link was when you said walking into a table and I was like, there it is.

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In today's research recap, we have three very interesting studies. One looking at autism and ADHD, and whether they have distinct executive functioning deficits. One looking at childhood identified ADHD versus ADHD where people don't have it identified in childhood are the differences between that. And then finally, a study looking at ADHD and depression. Is there a connection between ADHD and depression? And particularly, how can we test that? How can we make sure that is really a connection? So three very interesting studies, all quite different, and we're going to get into them today.

Do ASD and ADHD Have Distinct Executive Function Deficits? A Systematic Review and Meta-Analysis of Direct Comparison Studies.

So the first one that we're looking at is does ASD. So that's autism. and ADHD have distinct executive functioning deficits. So this is a systematic review and meta-analysis, which means they're looking at previous research to do their comparisons. What they were particularly looking for was, do children and adolescents with a diagnosis of ASD or ADHD have profiles of executive functioning, and they looked at different kinds of executive function, so that's working memory, timelines, etc. do they have distinctly different profiles? So Sarah, what did they find? Or how did they find it? This was sort of a culmination of 58 articles that they ended up with. To be included in this meta-analysis, the participants had to be under 19 years old, and then they had to have a group of people diagnosed with ASD, or a group of people diagnosed with ADHD, and also a control group. I guess no diagnoses. They also had to have studies that measured performance of executive functioning, so they didn't want anything that was just self-report of how someone thought they were handling it. Now, one thing that I was really, really unhappy with, and maybe it was in a longer version of the study somewhere, but it didn't provide definitions for all of the specific executive functions they were looking for. So I'm just going to assume they're like industry best standard. Yeah. When we've done this before, what we found is that it is different. People's descriptions of things like working memory can be really different. Just keep this in mind when we're going through it. It's also worth noting, we weren't looking at people who had a dual diagnosis of ADHD and ASD, and they specifically mentioned that this is something that was very new in terms of our diagnosis. With either you had ADHD or you had ASD, it wasn't both, even though we know that a lot of people have both. Yeah. So what were those different kinds of executive functions then Sarah? I am going to ask you to do your best. No, I got it. First, they were measuring sort of response inhibition. So sometimes we call that impulse control. It's basically just like being able to suppress the response until you can do the correct answer or make the right choice or whatever. And then there's working memory, which in this Meta analysis specifically, they're really talking about active recall, a specific type of working memory. There's also cognitive flexibility, which they also call set shifting. Sometimes we call it transitioning between tasks, so really just going from one thing to the next, whether it's a task to a task or a place to a place, that kind of thing. Which is tough. Which is really tough. Yes, it sure can. It can be a whole process, which is not conducive for research testing. There's planning they talked about, which is creating a plan to reach the goal, ordering the steps and so on. They looked at processing speed, attention, your ability to control that attention. And then they also looked at visuospatial abilities. So obviously this is really broad, but it generally relates to your ability to move. So being able to hold visual stimuli and understand their relation to other objects. So again, being able to estimate size. being able to give yourself enough space to not walk into that table, all that kind of thing involved in the visual space. That makes sense. I was wondering where the ADHD link was, and then you said walking into a table, and I was like, there it is. I found it. Definitely. Okay, so they were looking at quite a lot of different things, and they could do that because they were doing a mirror analysis. So what they were essentially doing was... they were looking for anything that was looking at executive functioning that met their criteria, and then they were excluding everything. So that's how they ended up with so many different measures. And they ended up with actually a review of 58 articles in total, which is pretty high for a systematic analysis. We've had as low as in the single digits sometimes in these studies. So that is pretty good. So what did they find in terms of the different ways that ASD and ADHD were affected with working with executive function? I have got to say that I'm actually really shocked by these results. Almost across the board, people on the spectrum, the ASD participants, perform significantly worse. Specifically, response inhibition, working memory, attention. Those were areas where the ADHD participants did better than their ASD counterparts. processing speed was sort of variable between studies. Some said that ASD was better, some said that ADHD was better, so there's real no consensus about that one. However, the ADHD participants performed significantly worse than autistic participants in one of the measure of visuospatial ability, but were sort of equal on the other three measures. It's probably the part about the working memory. Yeah, yeah, definitely. And then in terms of set shifting and planning, there was no significant difference between the populations. Well, I should say between the autistic and the ADHD participants, they performed all significantly worse than the neurotypicals, but that is to be expected. Yeah, that's what we find in these studies. Now, like I said in the beginning, I'm really confused by these results. What about you? I find them interesting as well because... particularly the attention one, the idea that ADHD population will perform better on a test of attention than an ASD population, it doesn't gel with the research and the diagnosis and what it looks like. We were actually talking about this a little bit off air and we're thinking, because we don't have all of the details of all of the studies, this is actually quite a short paper. It might have something to do with who were the people that they were studying in terms of ASD and in terms of ADHD, like were these populations very similar? Were they from inpatient facilities? Yeah, we don't have any of that kind of information, but it doesn't... Sound right? Yeah, well, you know, I think it could be very interesting if it is the case, but chances are, and this is something that we always talk about with this research, it's something to do with the paper not. necessarily something to do with the population. Yeah. So actually this brings us to the limitations because they said that they did a risk of bias assessment to basically evaluate their quality of articles and they found that to be medium high quality, but their external validity categories, which means the extent that these findings can be generalized to their respective population was low. Well, yeah, full stop. I think that pretty much, yeah, that pretty much sums it up. In terms of the practical implication of this paper, then it's less about, unfortunately, because it's a great topic. I think it's really good to consider how we're different and how we're the same. It does appear that this is more of an interesting conversation into the fact that there might be differences in ASD and ADHD executive functioning and what those are and what those look like. I will say just out of interest, this was published this year in the Journal of Attention Disorders, which is a pretty high journal when it comes to ADHD discussion, one of the ones we get the most. So it is interesting that they were obviously thought that this was worth publishing and worth discussing. And I think part of that is the meta-analysis. Part of that is the fact that it indicates that we need more studies looking at different ways, executive functioning of people. And I think the future study should include combined diagnosis and looking at people with combined diagnosis because that is very important group that we work with as well. Yeah, have you agree on that one? I also think that this highlights the need to standardize some of these executive functioning measures a little bit better and to make sure that the test that they're giving is actually measuring what they think it is. Yeah. I mean, in terms of like what this means for you, though, you know, there's sort of no roadmap on what we're going to struggle with and what we're not and not knowing your full diagnosis, sometimes not having access to that or just sort of not wanting to know, you know, it's, it's okay. Cause like that doesn't really matter. This really highlights to me that you can just look at each of those executive functioning challenges that are very common amongst the ADHD and the EISD population and just sort of like, evaluate yourself on each one. just to see where you tend to struggle and where you tend to shine. Because I'm sure there are things that you're good at, you know? Yeah. But going through each of them in that way will help you know what you need to work on. Yeah. So tell us what your executive functioning, the areas you're good at, the areas you struggle with. I'd be keen to know. I mean, we could almost do our own little study right now with the people who are listening to this podcast. I think that would be very interesting. Okay.

Compared Profile of Late-Onset Versus Childhood-Onset ADHD: A Case-Control Study Among Treatment-Seeking Adult Patients.

So the next study is comparing late onset versus childhood onset ADHD. This was a case control study and it was also from the Journal of Attention Disorders. This is complex because what they were actually studying was different from what I initially thought they were studying right at the beginning looking at the title. So what they were looking at was do adults with childhood onset versus adult onset ADHD differ in terms of their symptoms, their demographics, their outcomes? but they didn't mean diagnosed in childhood versus diagnosed in adulthood. They meant something else. So tell us what they meant, Sarah. Yeah, so childhood onset ADHD means that your symptoms were present in childhood. And late onset or adult onset ADHD refers to when your symptoms only begin once you reach adulthood. Yeah, so all of these people were actually diagnosed sort of... at the same time or as part of this study, which is kind of cool. Yeah. So they were all diagnosed in adulthood, basically. Yes. And they used destruction interview. They used the DSM criteria as part of the diagnosis. So that was good. Yeah. So let's get into it then. They had 101 adult participants. 56 were classified as childhood onset and 45 were classified as adult onset. Pretty even split. They measured ADHD using what's known as the DIVA evaluation. It's based off of the DSM-IV, but it's sort of more than just the criteria. It separates people into subtypes, so inattentive or hyperactive, as well as when your symptoms first began manifesting in your life, sort of presenting themselves in your life. Manifesting. I love that. Yeah. You know, they did other self-report surveys to measure things like anxiety, quality of life, et cetera. And then they did a whole horde of performance tests to measure different executive functioning and cognitive abilities. Yep, including the strip test, the trail-making test, all the usual suspects. We actually do have some new ones in this list today. Oh, nice. Yeah, I was really excited. New stuff all around. There's one which is just measuring sustained attention. So it's your ability to sit at a computer continually select the correct response, even when you get bored of sitting there. There's the digit span test, which means they're going to tell you numbers and then you have to remember them and enter them correctly. That apparently was a working memory task, but I think it's really interesting because that only accounts for verbal working memory. Interesting. Interesting as opposed to as opposed to non verbal working memories. So something like walking into a room and remembering where your keys are. Yes, of course. Yeah. No, that's very, very interesting. And that's another thing that I alluded to earlier, where like, is the thing that you're trying to measure actually the thing that you're measuring? Or anyway. Oh gosh. And is it the same thing as what other people are measuring? 100%. Yeah. And then there was this awful one. This sounds terrible. The multiple errands test. Basically, they give you instructions and they say you have to get all of these items and here are all the stores that you can go to. Now tell me how you're going to do this. Where are you going first? I'm going to find a place that does delivery. Yeah, I was reading about that going, oh my goodness, that is so many executive functions right there. That's so funny. Yeah, well, I do appreciate the real life aspect of it. Yeah. But yeah, I'm just like, I'm going to find delivery apps that will take. Yeah. So in terms of what they found, it was interesting. It was what you expected, but then their discussion of it was not what I expected essentially. So they found that childhood onset ADHD, so just a reminder that people who showed symptoms of ADHD in childhood, not children with ADHD, it was associated with lower educational attainment, increased risk of childhood trauma, a lower BMI, higher impulsivity, higher risk of cannabis and alcohol use. So it was associated with a lot of these, we would say external factors, and The groups did not differ when it came to their anxiety, their sleep impairment, depression, quality of life, or autonomy. So how they felt seemed to be the same, but how they presented seemed to be different. They also found that only working memory differed between participants. Those with childhood onset ADHD tend to have more impaired working memory, according to the one study. So yeah, Sarah, what did you think of these results? Oh, that's an interesting way to phrase that question. We talked a little bit about this in the beginning, and you just said the results are what you'd expect, but the discussion is not what you'd expect. So they sort of suggest that people who have symptoms in childhood have more severe cases of ADHD. They also sort of found that the women were overrepresented in the adult onset sample, as opposed to sort of in the childhood sample, which is... another piece of literature saying that women don't have ADHD as a child, you know, really interesting. Yeah, but in terms of what did you think of the results as a whole? So they suggest that maybe those people have the more severe symptoms, but then they don't really account for the fact that retrospective, like thinking back to your childhood is not always very reliable in terms of the symptoms that you experience. and they sort of say that a little bit later in their paper. Like, yeah, we know that this is a little bit controversial, but that's it. I think that's probably a good way to describe this paper. This paper is a little bit controversial because of how it did this. There's good reasons not to, but they definitely could have looked at a group of people who had ADHD diagnosed in childhood and a group of people who had ADHD diagnosed in adulthood and compared those two groups. and then we would be looking at self-reporting. But for some reason they chose not to do that. What you end up getting is more of a discussion, a little bit on masking because what you're seeing here is basically people who said that they felt like they have ADHD in childhood, all of the different things, lower educational attainment, increased risk of childhood trauma. These are things that were external factors. These are things that other people could have potentially identified. And I wonder if part of this was whether you were good at masking your ADHD or not. There's definitely a lot of other factors as well. And whether you were aware you were masking your ADHD or not. Yeah, and that as well. And I think the more interesting factor is that it appeared that how you felt internally, so depression, sleep impairment, anxiety, quality of life, these things didn't change depending on whether you seem to have symptoms earlier or not. So the things that did seem to change with the sample with things maybe other people remarked on. So when they asked you, do you think you had childhood onset ADHD, I wonder how many people were thinking back, well, my teacher said that I didn't do very well in school or I got caught drinking earlier than I should have, looking back, that kind of thing. Those factors. It is interesting. It sort of seems to potentially be partially dictated by how people remember things. What would indicate ADHD if you were thinking about it retrospectively? And then also just the fact that it seems to be like the internal feelings are similar for both groups. Yeah, they also kind of wanted to look at how your IQ played into, well, really all of this, age of presentation as well as like the specific struggles. But they couldn't do that. They don't say why, they just say they couldn't do that. We couldn't do it. Unfortunately, that would have been sort of a unique spin to this paper. But unfortunately, we're just looking at the looking at external factors. They say in the beginning, we're just looking at the differences between these groups and they did that. But I feel like there's not really anything anywhere to go from it. Mm-hmm. Yeah, it's interesting, the IQ. conversation when I was one of the first things we studied in psychology was the fact that it's almost impossible to measure IQ in many ways. People continue to try and people do continue to do it, but when you actually look at it, there's just so many ways to measure IQ, so many different cultural factors. Maybe that's why, I don't know, but they just said they couldn't do it. In terms of the practical implications, you know, they said it's potentially the DSM requirement for ADHD symptoms to be observed in childhood in order for a diagnosis to be made Might be something that we want to reconsider and this is something that a lot of people have talked about More and more people particularly women are getting diagnosed later in life The idea that you have to have evidence of ADHD diagnosis or ADHD symptoms earlier Nevermind retrospective thoughts about it sort of biases you towards these external symptomology. So external things of like, well, they were very loud or they never paid attention in a very obvious way. I did think the discussion of the idea of more research into splitting people who have diagnosed childhood and diagnosed adulthood ADHD might be quite interesting. I definitely think maybe going for somebody who actually got diagnosed in childhood versus somebody who retrospectively but actually got diagnosed in adulthood is probably a better way to go next time. Yeah, I mean, I think it would be really good if they could sort of see whether symptom severity has any sort of play into this. Is it really true that it's just the people with severe symptoms that we're sort of treating? How can we maybe identify people who are also having symptoms but just not sort of disruptive? That could be helpful to get more research around. You know, so separating people in that way, you know, childhood versus adulthood could be interesting. I think it's also sort of a new idea and it's definitely not agreed upon in the medical community whether or not you can get ADHD for the first time in adulthood. You know, this whole idea of adult onset is sort of controversial. So yeah, it is a very controversial. And again, it's interesting that it was published in general, but tangerine disorder. It really does. indicate just a lot of new things coming out. Yeah. I think that there is a conversation to be had about whether the ability to successfully mask means that your ADHD is less severe. Because I think that those two things are not necessarily the same. No. But in this case, they are discussed similarly and then masking is not discussed at all. Just because you do not appear to have ADHD doesn't necessarily mean that you don't have symptoms. It might just be that you're... working very hard behind the scenes to do that. That might be something that certain people have the resources to do better than others, which is a whole other conversation. Lots and lots of interesting conversations to be had. We'd definitely love to see more research in this area for sure.

Attention deficit/hyperactivity disorder and major depressive disorder: evidence from multiple genetically informed designs.

Then our last paper is from biological psychiatry, and it's looking at ADHD and depressive disorder. Particularly, what they're looking at is Is there a relationship in adolescence between those who have ADHD and those who develop what they call major depressive disorder or MDD and later life? Which is a topic that I think we've covered before and it's interesting in this case what they wanted to do was they wanted to look at various genetic methods to study and to answer this question. So they were looking at siblings, they were looking at twins and they were looking at what were identified as two sample Mendelian randomization analysis, which was basically, if you remember our discussion with Abby a couple of weeks ago, measuring gene variation to examine potential causal effect. So was there variations in genes? So what did they find from this paper, Sarah? Yes. So, I mean, in sort of all of those different ways that they were trying to analyze this data, they found pretty significant evidence to suggest that an ADHD diagnosis has a causal relationship with developing major depressive disorder later in life. So basically, if you receive an ADHD diagnosis, then I think what they found in one of the four-fold increased risk of depression developing later in life, or if your sibling had ADHD. I mean, you know, so yes, very much there is absolutely a genetic relationship here, and at least according to this study and their various methods, they did sort of show that there's a causal relationship between ADHD and major depressive disorder, which again, didn't feel surprising. It didn't feel surprising, but the fact that they focused on causal effects was surprising because, you know, often when two things correlate, we talk about correlation, and they did a lot of work to try and have that causal discussion. But I'm curious, Sarah, what was it that made them think that it was causal specifically? The Mendelian randomization analysis indicated evidence of a causal relationship. So basically all of the different ways that they analyzed this data showed. somewhat of a causal relationship. That's really interesting. Where, Sarah, did they actually get the samples from? We didn't mention this in the beginning like we usually do, but they were sort of pulling from over a million data points. And they were using- Wow. Yeah. That might be a new record. Well, this is gonna sound familiar. They were using the Swedish twin registry and other sort of registries that they have. And they just keep this data. looking at siblings, looking at twins, looking at everything so that they can do this really intense genetic research. So thank you, Sweden, really coming in handy. Yeah, yeah, very, very cool. Yeah. Yeah, so I've been looking into the causal element of it, you know, while we've been on air. It is interesting. I would be curious, you know, maybe we need to have somebody from the Sweden study on. actually to discuss these kinds of things because there's a lot of ADHD research coming out of this group in this area would be interesting to actually speak to somebody who is involved in some of this research in Sweden because you know there's different factors and yeah it's quite a bold statement to make for sure. I mean absolutely sort of what I can get out in Lehman's terms is that you know it's related to that Mandelian stuff it's just a bunch of And so they were looking at the genetics. So they found genetic correlations between depression and anxiety. And then they go on to say, evidence of a causal effect of genetic liability for ADHD on depression. So sort of how much of that is because of your genetics. So I think that's really where that causal relationship is coming from. Yeah, it would be- It's really hard to sift through though. Yeah, we're gonna- We're going to have to send this to Abby. Yeah, we'll send this to Abby and we'll see what she says. Maybe we'll have it back to discuss it because it is very interesting. In terms of the limitations, they did say that again, they used questionnaires. They didn't use professional clinical assessments, which is always a really good limitation to identify, and possible selection bias couldn't necessarily be too broadly generalized. to adults specifically. So all of this data is collected on children and adolescents. Yeah, exactly. So in terms of their practical implications, identifying a causal relationship between ADHD and depressive disorder is huge. That's a pretty big practical implication. Even though the study's been done before, the fact that they had such a large sample and they went and looked at twins and they went and looked at genetics and siblings. indicates that this is a very real factor and something that might be worth actually considering in terms of if you have ADHD, does this mean that you're now potentially at risk? Yeah, and if you do find yourself at risk, you know, all the same emotional self-regulation stuff that we talk about in terms of ADHD is going to be pretty important. Yeah, it might be worth it to sort of seek additional supports, even if you don't feel like you need it at the time. You know, really anything that you can do to further develop your understanding of grounding and coping and anything mental health related. This study is pretty strongly advocating for that. Definitely, definitely. Okay, well, a bit of a somber note to end on today, but overall three very interesting, very different studies and all the studies I think had this very interesting, sometimes the methodology and how a study is done is almost as interesting, at least for me as a research nerd, as the study itself. So having a look at that idea of. ADHD and ASD having executive functioning deficits, but also the fact that it was a minor analysis and that had a few gaps in terms of how that worked. The idea of late onset versus childhood onset ADHD, the fact that they didn't actually look at children and they used different ways of doing it. And then here we've got finally the major depressive disorder study in Sweden with a million people and really trying. to nail down this concept of the connection between ADHD and depression using a whole variety of different ways of testing it. But at the same time, still having that limitation on using questionnaires rather than clinical assessment of ADHD, which is really always a big factor. So a lot of people did some interesting things, but at the same time, a lot of very clear limitations to the studies as well. Yeah, really cool titles, really cool topics, but you know, just a reminder to always read the fine print, you know, take all the information into context. Yeah, I think that's so true. You know, this is this was a week where I went in thinking the study would be one thing and came out finding out that it was another in the multiple cases. So definitely always good to check the methodology or have a look back if you do find that you're of getting told one thing and you just want to check in as much as possible or just listen to this podcast, well we'll do it for you. Awesome. So yeah, have a great week and we will see you again soon with another research recap. See you then. 

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