Research Recap with Skye: Hay Fever and ADHD
Welcome to Hacking Your ADHD. I'm your host, William Curb, and I have ADHD. On this podcast, I dig into the tools, tactics, and best practices to help you work with your ADHD brain. Today, I'm joined by Skye Waterson for our Research Recap series. In this series, we take a look at a single research paper and dive into what the paper says and how it was conducted, and try to find any practical takeaways.
In this episode, we're going to be discussing a paper called "Bidirectional Association Between Allergic Rhinitis and Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis." This is a comprehensive study looking at the relationship between allergic rhinitis—which is more commonly known as hay fever—and ADHD. All right, let's get into it.
If you'd life to follow along on the show notes page you can find that at https://HackingYourADHD.com/305
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William Curb: Welcome to Hacking Your ADHD. I'm your host, William Curb, and I have ADHD. On this podcast, I dig into the tools, tactics, and best practices to help you work with your ADHD brain. Today, I'm joined by Skye Waterson for our Research Recap series. In this series, we take a look at a single research paper and dive into what the paper says and how it was conducted, and try to find any practical takeaways.
In this episode, we're going to be discussing a paper called "Bidirectional Association Between Allergic Rhinitis and Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis." This is a comprehensive study looking at the relationship between allergic rhinitis—which is more commonly known as hay fever—and ADHD. All right, let's get into it.
Skye Waterson: A couple of weeks ago, Will said to me, "Hey, should we look at some research to see if there's a connection between hay fever and ADHD?" And I went, "I mean, we could see if there's something." And then my research assistant found more papers connected to this topic than we have on almost all the other topics. It turns out there's a ton of people who have wondered the exact same thing as you.
William Curb: Yeah, I was very surprised because a lot of times when we're discussing topics, I'm just like, "Oh, is this something I've ever dealt with or heard about? I'll suggest that as a topic." And this was just like, "Man, my allergies are killing me. I wonder if there's a connection there." And it was one of those things where, apparently, yes.
Skye Waterson: Yeah. So we have a meta-analysis on this, which basically means that so many people wanted to know this that they did a ton of different papers on it, and then somebody summarized all of those papers—particularly looking at the relationship between... I thought this was really interesting. Not just ADHD being connected to hay fever, but also whether hay fever is connected to the development of ADHD.
And obviously, this is all correlation. None of this is causation. If you've ever seen the thing about ice cream in New York, you'll know that correlation and causation are not always the same thing. But it was really interesting. They ended up only including 18 different studies. They started by looking at about 1,000 different studies and then worked it all the way down to just 18 different studies of hay fever and ADHD.
William Curb: Although to mention, from those 18 studies, there are 4.2 million participants. These were studies looking at a large number of people.
Skye Waterson: That is very true. Well done to them for actually finding that. Okay, they also did a little look at ASD, which I thought was interesting, but they didn't find anything conclusive. But that was in the picture as a part of the conversation.
William Curb: Yeah, there were some indications that there were connections between ASD—Autism Spectrum Disorder—but yeah, again, nothing conclusive. So it is something that maybe in the future we'll see more on, especially because one of these things that we're seeing, this crossover, comes from inflammation, which is definitely something that plays into both ADHD and autism as well.
Skye Waterson: Yeah, and we have actually already looked at a paper on inflammation, so if you want to find it, you can search back through the history because we've talked about that.
William Curb: Yeah, we'll see. Maybe we'll do another one at some point because...
Skye Waterson: Yeah, well, maybe. It seems to be a thing. So they were looking at the bidirectional relationship, and what they found was that compared to individuals without hay fever, those with hay fever faced a 1.83-fold higher risk of developing ADHD, which literally just blew my mind. This whole paper is filled with just me writing question marks and exclamation points everywhere.
William Curb: Yeah. I mean, as you said with correlation, we don't know which way it's going, but seeing that result is like, "Oh yeah, if you have allergies, you're more likely to have ADHD, and if you have ADHD, you're more likely to have allergies." It is wild. Especially because—well, and this is somewhat interesting in the US as we are having a spike in allergies because of climate change issues, how long trees are releasing pollen, and how much they're releasing.
But I should say that hay fever isn't just pollen. You also have mold, pet dander, and all these other allergens that can cause this reaction, which is like the release of cytokines that I don't want to get too far into because I don't understand that science that well.
Skye Waterson: But in general, how does it make you feel for those of us who don't experience allergies?
William Curb: I'm actually doing better this year than I did last year because... but it's kind of like getting punched in the face where my sinuses just swell up and it hurts so much to just exist. Last year I was reading my page-a-day journal and it was like, "Oh yeah, last year I got a prescription for a steroid to help deal with the inflammation in my face," because I could not do anything. It was just like I was in pain all day long from how much my sinuses were inflamed.
Skye Waterson: Yeah. I think that's really important because it's not just like the sniffles or something that you might see. This relates to the correlation and causation conversation. One of the things they did mention was that sleep could be affected by having these kinds of allergies. Based on what you said, I think brain fog would probably be a factor as well. So there is a bit of a complicated conversation with relation to if you really did struggle with hay fever, and then they gave you a thing about being distracted and struggling with focus... well, we know that when we're diagnosing kids with ADHD, one of the things that they're doing is a check of sleep disorders, and this might be a version of a sleep disorder.
William Curb: Yeah, absolutely. When you can't breathe at night, it makes it much harder to sleep, and when you do sleep, you get worse sleep. So often you see with sleep apnea that treating the sleep apnea will basically make the ADHD symptoms disappear because it was all due to the lack of sleep and them getting used to it and just being like, "I'm so brain foggy and this is just how life is."
Skye Waterson: Yeah, exactly. And so when I'm working with clients, we do a baseline check: what is your sleep like? What is your exercise like? You know, all of those things that are likely to be shifted if you're struggling with something like hay fever. I guess one of the interesting things they mentioned was—because they worked with a lot of people from primarily Asian countries—they talked about this idea of rapid urbanization and maybe that was affecting the growing number of people who are struggling with hay fever. Obviously, you mentioned climate change. It feels like this paper is a bunch of arrows pointing to one another, but not necessarily a solid link.
William Curb: Yeah, 100%. It's one of those things where it's great preliminary research to be like, "There is 100% a link that we need to look into." And so I don't want anyone to come away from this being like, "Oh, either allergies cause ADHD or ADHD causes allergies." That's not something that we know yet, but it is something where we're like, "Oh yeah, you're just more likely to have both."
Skye Waterson: Yeah. And so what they took away from it was if somebody presents with hay fever, it might be worth telling them that they are also more likely now to present with the symptoms of ADHD.
William Curb: Yeah. And one thing I always find with these things too is because of how we assess ADHD—you know, it's like these thresholds of detriment in your life. And so if you have something like hay fever, it's going to increase your detriments across multiple areas of your life. And so then you're starting to hit these thresholds much more likely because—oh yeah, if I'm going from forgetting my keys occasionally to chronically not being able to find anything, you're now clinically diagnosable with ADHD because you're hitting these thresholds.
Skye Waterson: Yeah, exactly. It's an interesting conversation, and it also adds to that piece on how people are always interested in the connections. Like, "Oh, I didn't realize this could be connected to ADHD." And for those of you listening, now we have another one.
William Curb: Yeah, it's something. And there are so many ways that it can work, too. While I don't want to talk about the individual science too heavily, there's stuff like how this chronic inflammation from hay fever can affect things. You know, you have stuff where it's like the blood-brain barrier isn't as strong, and so you have more allergies from that kind of thing. And then you can have stuff with neurotransmitter metabolism being not as effective. So suddenly you go, "Oh, dopamine is not as effective with hay fever." That feels like it's connected.
Skye Waterson: Yeah, 100%.
William Curb: Um, so is there anything else you want to talk about with this paper?
Skye Waterson: I think I found it really interesting that... I guess my biggest thing was, why are so many papers spending money on this? Doing this research costs money, and there are many things related to ADHD that I wish people would study, and they don't. And then suddenly this one has all of these different papers that made me curious. There was no financing mentioned for this. This obviously comes from the University of Chinese Medicine. I'm just curious about the reasoning behind so many papers about allergies and ADHD, because it doesn't feel like a natural fit, at least to me.
William Curb: Yeah, I agree. As I said when we were picking the topic, I was like, "Oh, I'm just experiencing this. I wonder if there's a connection." And it is interesting that it's not just me experiencing this curiosity about this connection enough so that there's a lot of research going into it, but not a lot of conclusive research yet.
Skye Waterson: Yeah. It does make me wonder if there is a universe—and I don't know, so please don't hold me to this—if there is a universe where people are going, "What would happen if we found a really good way to deal with hay fever?" They're both medication-based supports. What does that look like? I wonder if there's something being built because they're investing a lot of money in these papers on this topic.
William Curb: Yeah, I could definitely see a potential for drug companies trying to be like, "Oh yeah, this is something we can definitely make a dime off of."
Skye Waterson: Mm-hmm. Yeah. And maybe not. Maybe they just really want to help us out and give us that research. Let's hope it's that one.