This week we’re going to look at what is entailed in ADHD research—what it is, how it works, and what it all means for us.
Before we get going though I wanted to start with a brief explanation of what really drove my thinking about this topic—which now looks like is going to end up as a multi-part series.
So there’s an idea called the illusion of explanatory depth, which occurs when people believe they understand something but, when asked to explain it, realize that they don’t quite understand the underlying mechanism as well as they thought. Classic examples are things like how a computer works, how a bicycle stays upright, or how a toilet functions.
If I were to ask you how any of these things work I expect most people would say they could. But let’s take the toilet example—I know personally, I’d probably start with something about the flush adding water and maybe creating a difference in pressure and… okay maybe I don’t know how a toilet works. And that’s the point here: with the illusion of explanatory depth, we have some understanding of what’s going on, but when pressed for details, we often find those gaps in our knowledge.
And this was something that I was feeling about ADHD research and had me questioning what I really knew. That isn’t to say that I didn’t know anything but we hear all the time that new studies are coming out about ADHD, but what does that really mean? How is this research being conducted? Who’s funding the research? What are ADHD scientists actually studying? Who's doing this research? What kind of research are they even doing? And what even makes one research study better than another?
We all have some semblance of feeling like we know some of the answers to those questions, but this is also where the illusion of explanatory depth comes in because the answers to all of those questions is far more complex than our initial assessment would grant.
In this series, we’ll be examining these questions more closely. And in this particular episode we’ll be focusing on the different types of research, the methods used, and some the challenges that researchers face when studying ADHD.
I also want to emphasize that I will not be able to cover everything in this series, but that’s not the goal. What I’m hoping you get out of this is a better understanding of what goes into the making of the science of ADHD.
Broadly speaking, ADHD research can be divided into three categories: basic research, clinical research, and behavioral research.
Basic research—which is also sometimes known as pure research or fundamental research—is about improving scientific theories to create a better understanding of what is being researched. In the case of ADHD, this means that the research is looking to better understand the underlying causes of ADHD.
This includes neuroscience studies that focus on brain function and structure. They do this through functional MRI (fMRI) and Positron Emission Tomography (PET) scans, which allow them to observe brain activity in real-time. These kinds of studies allow researchers to see what areas of the brain are activated when a person is paying attention, managing impulses, or performing tasks that require executive function.
One of the main findings from these studies is that people with ADHD often show differences in the prefrontal cortex, the part of the brain involved in decision-making, attention, and controlling impulses. The prefrontal cortex tends to be less active in individuals with ADHD, which helps explain why they often struggle with planning, organizing, and staying focused.
Recent neuroscience research has also produced new details on the default mode network (DMN), a network of brain regions that’s active when you’re not focused on a particular task—it’s the parts of the brain that are lit up when you’re daydreaming or letting your mind wander. However, in individuals with ADHD, it seems that this network may stay active even when we’re trying to stay focused on a task, which, honestly, makes a ton of sense to me. Personally, I think this is going to be one of the most interesting areas of ADHD research in the future as I feel like this may hold a big key to the picture of why it’s so hard for us to keep our focus.
In addition to neuroscience, we also have genetic studies that explore the genetic nature of ADHD. Because while we do know that ADHD has a genetic component, there is still a lot we don’t understand about how that exactly works.
Genetic studies focus on identifying the specific genes that may increase the likelihood of developing ADHD. One of the primary tools for this is genome-wide association studies (GWAS). In these studies, researchers analyze the DNA of thousands of people with ADHD and compare it to the DNA of people without the disorder. By doing this, they can identify small differences in the genetic code that are more common in individuals with ADHD. These differences can provide clues about which genes may be involved in the development of the disorder. One exciting area of genetic research is epigenetics, which looks at how environmental factors—like stress, diet, or exposure to toxins—can affect the way our genes are expressed without changing the underlying genetic code. This means that while you might have a genetic predisposition to ADHD, certain environmental factors could trigger or potentially worsen your symptoms. Of course, we’re very early in this research so it’s hard to say what those factors actually are.
Neuroscience studies are helping us understand the "why" behind ADHD behaviors by showing us how the ADHD brain functions differently—it gives us a biological basis for ADHD, and genetic studies help us understand the biological roots of ADHD and how our genes interact with the environment to shape the symptoms we experience.
Clinical research is what most people are thinking about when they hear about ADHD research. In clinical research, they are testing different treatment options and what works best with ADHD brains.
One of the most common forms of clinical research are randomized controlled trials (RCT), which are considered the gold standard for testing the effectiveness of new treatments. In an RCT, participants are randomly assigned to either a treatment group or a control group. The treatment group might receive a medication or therapy, while the control group might receive a placebo or standard treatment. The randomization helps eliminate bias, ensuring that the results are as objective as possible.
While the most common type of clinical research is looking at the effectiveness of medications, clinical research also tests a host of non-pharmacological treatments such as cognitive behavioral therapy (CBT), mindfulness practices, or even recently, digital therapeutics like apps and video games.
The aim of these studies is to measure how well interventions help people with ADHD improve things like their executive function. For example, in a CBT trial, participants might learn strategies for managing procrastination or dealing with emotional overwhelm. Researchers then track whether these skills improve daily functioning and reduce the impact of ADHD symptoms over time. So, we see studies testing the effectiveness of medications, therapies, and lifestyle interventions and examining how those methods actually work. The goal is that clinical research can bridge that gap between theory and practice.
Finally, we have behavioral research, which studies how ADHD impacts daily life. In many ways, behavioral research overlaps with clinical research; however, behavioral research tends to be more expansive. Research is often done in observational and longitudinal studies, which examine how interventions affect participants in real-world settings.
For example, a study might observe how children with ADHD behave in a classroom setting compared to children without ADHD, focusing on attention, impulsivity, and social interactions. Or you might have a study that follows children with ADHD from elementary school through adulthood, tracking academic performance, career success, social relationships, and mental health outcomes.
Those examples also illustrate that a lot of this kind of research is done on children. This is often due to the typical age of diagnosis, the developmental nature of the disorder, and the goal of early intervention. That isn’t to say that there is no adult behavioral research being done; it’s just more sparse than the research conducted on kids.
Behavioral research is often focused on executive function, social behavior, and the long-term effects of ADHD on life outcomes. By studying behavior, researchers look to develop practical tools and strategies for ADHD. Behavioral research can give us insights into how ADHD truly affects day-to-day functioning beyond the more obvious symptoms of inattention or hyperactivity.
With that understanding of what goes into ADHD research, I also want to discuss some of the limitations that come up.
And one of the biggest issues comes from the fact that ADHD is a spectrum disorder—mean that it can look incredibly different from one person to the next. There are three presentations of ADHD: Predominantly Inattentive, Predominantly Hyperactive-Impulsive, and combined. And even among those presentations, no one is going to have the exact same symptoms. This variability can make it harder for researchers to find universal patterns that apply to ADHD. This something that I have to deal with when writing for the show is and is often why I couch my language with this like “many people with ADHD experience x” because I know that not everyone is going to be dealing with the same issues.
For example, I rarely struggle with being late to things, but that’s often more to do with my anxiety around being late, which brings us to our next problem with ADHD research, which is the high number of co-morbid conditions.
It is estimated that 60-80% of people with ADHD have some sort of co-morbid condition. These can range from anxiety and depression to autism, a host of learning disorders, and sleep disorders.
With this range of co-occurring conditions, it can be hard to pinpoint what’s ADHD and what isn’t. And this is an important thing for researchers to take into account when it comes to developing treatment options because we want to make sure we're treating the right things.
Diagnosis is also a tricky area for ADHD because the process is somewhat subjective. A typical diagnosis comes from behavioral assessments, self-reports, and interviews. There’s no blood test or brain scan that can definitively say whether someone has ADHD. And this can be an issue because the symptoms of ADHD might come from somewhere else. This is often why clinicians are so hesitant about self-diagnosis. If your ADHD symptoms actually come from a sleep disorder, then the treatment plan needs to be focusing on another issue.
These limitations in the diagnostic process make it hard to determine who should be included in studies on ADHD. Cultural factors, expectations, and even gender norms can affect how ADHD symptoms are perceived, which means some people may be overdiagnosed while others may be underdiagnosed. This can skew data from where ADHD is more normalized or highly stigmatized. This doesn’t mean that research isn’t worthwhile, but it does mean that we have less reliable research on how ADHD affects these underserved populations.
For example, we have many gaps in understanding how ADHD affects women differently because ADHD is typically diagnosed in children who are considered disruptive—that is, if you have a hyperactive-impulsive presentation or combined presentation as a child, you are more likely to be assessed for ADHD. The whole squeaky wheel gets the grease thing, but also, we’re more likely to be on the lookout for those hyperactive-impulsive symptoms because those are the classic symptoms we see in pop culture. While research points to women having around the same rates of inattentive ADHD as men, it seems they are less likely to have hyperactive/impulsive symptoms. And that may only be because of different societal expectations of women and girls.
The point is that women typically receive fewer evaluations for ADHD, and therefore, we have data that points to ADHD being more common in men—but that is incredibly hard to accurately assess based on our current diagnostic system because one group is simply more like to even be assessed for ADHD than the other.
This is also true across cultures, as we see that diagnosis rates vary significantly by country, culture, and even within regions of the same country. In some places, ADHD is diagnosed more frequently, whereas in other places, the condition is underrecognized or stigmatized. This inconsistency poses a major challenge for global ADHD research, as comparing studies or generalizing findings across different populations becomes difficult.
Fortunately, more research is being done to explore these underrepresented populations, but we’re still playing catch-up in many ways.
To sum it all up, ADHD research is complex and multi-faceted, with researchers exploring everything from brain function to emotional regulation, genetics, and environmental factors. But despite the progress that’s been made, there are still plenty of challenges, including the variability of ADHD symptoms and the difficulties in diagnosis.
In the coming weeks, we are going to continue looking into ADHD research with next week focusing on where we can find good research on ADHD and how we can evaluate what’s worth listening to and what we should avoid. I’m already working on that episode, but if you’ve got any questions regarding ADHD research send them my way by heading over to hackingyouradhd.com/contact and I’ll do my best to get them answered.