Neuroscience of ADHD
ADHD is one of the most common diagnoses for kids, and many adults today claim to have it.
But what if we told you we don't know enough about it to cure it... or prove it exists at all?
Research shows that over 9% of children are diagnosed with ADHD, but considering how common it is you'd think we understand a lot of what's going on and why certain therapies or medications help to relieve symptoms.
Yet what we know (or don't know) about it will shock you.
So what DO we know about the brain and ADHD?
And if it's not ADHD... then what could it be?
Tune into this month's deep dive into the neuroscience of ADHD where Laine walks us through the controversial science from Slater, Tate, Rubia, and many others looking at
what we know so far
why do we know so little
and what we can do about it
We mention some studies from previous episodes as well, so if you haven't yet feel free to check them out via the links below.
Mini Episode: Neuroscience of Motivation
Season 1, Neuroscience of Music
TIMESTAMPS
2:01 - What is ADHD?
8:06 - The Shocking Truth
11:27 - The History (Caveman Jo?)
13:34 - Why Neuroscience?
16:17 - Break
16:34 - The Brain...?
24:19 - What we (somewhat) know
25:26 - Neural Networks
36:50 - Break
37:05 - The Great Misdiagnosis?
41:40 - Takeaways
RESOURCES
CDC: Toward Systems Neuroscience of ADHD: A Meta-Analysis of 55 fMRI Studies
Leanne M Williams, Tracey W Tsang, Simon Clarke, and Michael Kohn - An ‘integrative neuroscience’ perspective on ADHD: linking cognition, emotion, brain, and genetic measures with implications for clinical support
Jessica L. Slater and Matthew C. Tate - Timing Deficits in ADHD: Insights From the Neuroscience of Musical Rhythm
Carlos Acuña - The ADHD-200 Consortium: a model to advance the translational potential of neuroimaging in clinical neuroscience
Katya Rubia - Cognitive Neuroscience of Attention Deficit Hyperactivity Disorder (ADHD) and Its Clinical Translation
General Outline of Episode
Have you noticed how short our attention spans are nowadays?
Short, attention-grabbing videos + dopamine = mindless entertainment
Boredom feels more uncomfortable
Our minds are constantly all over the place
No surprise that so many of us think it might be ADHD…
Might explain why there are so many diagnoses of it as well.
This is the neuroscience of ADHD.
LAINE
CDC states that ADHD is “ADHD is one of the most common neurodevelopmental disorders of childhood.”
Stating “The estimated number of children aged 3–17 years ever diagnosed with ADHD, according to a national survey of parents, is 6 million (9.8%) using data from 2016-2019. This number includes
3–5 years: 265,000 (2%)
6–11 years 2.4 million (10%)
12–17 years: 3.3 million (13%).
Boys (13%) are more likely to be diagnosed with ADHD than girls (6%).1
Black, non-Hispanic children and White, non-Hispanic children are more often diagnosed with ADHD (12% and 10%, respectively), than Hispanic children (8%) or Asian, non-Hispanic children (3%).”
The National Institute of Health states that 4.4% of adults have ADHD, with 5.4 vers 3.2 found in males and white individuals higher than all other races.
ADHD(colloquially) - Synonyms - hyperactive, short attention span. We are turning it more and more into slang for ‘easily distracted or all over the place”. Squirrel
ADHD(clinically) - Pattern of inattention and/or hyperactivity-impulsivity that interferes with function and development as characterized by Inattention (must have 6 or more symptoms of inattention) and Hyperactivity and Impulsivity (with 6 or more symptoms) that have both been present for at least 6 months and is inconsistent with developmental levels and causes clinically significant distress - must see this before age 12 and must be present in more than 2 settings
ADHD - It is one of the most overdiagnosed diagnoses we have, without question. According to the global health review, Psych Central, Cleveland Clinic, and the National Institute of Health - it is one of the most commonly misdiagnosed disorders WORLDWIDE. We have study after study to prove this. ADHD symptoms overlap with so MANY other conditions. Inattentive, irritable, trouble sleeping, problems at school, dysregulated, not listening, not focusing, easily distracted, poor working memory - these are all found all over the DSM.
PART 1: Terms & Background Info (5-10 minutes)
Don’t go back to BC for this one. There are descriptions of children being distracted and having trouble focusing in 1798 and 1902 specifically but that does not mean it was ADHD. In 1932 Fran Kramer and Hans Pollnow from Germany identified children who had trouble sitting still, dysregulated, and focusing and called it Hyperkinetic Disease. Most of these children got better as they got older. Again - likely not a disease.
In 1937 Charles Bradly noticed a stimulate that caused some children to improve school work and regulation. A diagnosis was not until 1968, in the second edition of the DSM, called Hyperkinetic Reaction of Childhood. 1980 is when it was called Attention Deficit Disorder and ADHD did not exist till 1987.
PART 2: What About Neuroscience (5 minutes)
To quote the meta-analysis of 55fMRI studies on the Neuroscience of ADHD” “ adhd pathophysiology remains incompletely understood”
Williams, Tsang, Clarke, and Kohn state that there is “a translational gap” between neuroscience knowledge and our knowledge in clinical practice. Often in clinical work, we treat this with behavior, and how to function in a neurotypical world, but most clinicians who are treating this know little about what is going on in the brain if someone has ADHD. Clinicians are focused on trying to make someone successful in life, but this is often done with little understanding about what is going on that is causing struggles.
**BREAK**
PART 3: The Science (30-35 minutes)
Acuna - understanding of the pathophysiology of ADHD is insufficient. “Equally problematic, translational promises have yet to be delivered, as clinically useful biomarkers are rarely attained” and notes “Psychiatry remains uniquely reliant upon a diagnostic and classification system derived from clusters of symptoms rather than etiology or neurobiology”
Slater and Tate agree saying “Despite significant research efforts, characterization of the neurobiological basis of ADHD has proven elusive”
Saying even though we list this as a neurological disease, essentially we diagnose this based on a self-report questionnaire, give you medication, and see if it works”
They state “it has been difficult to identify biomarkers of the disorder because there has been no clear mapping between neural measures and clinical subtypes. Although ADHD is associated with structural and functional abnormalities, including within frontal, striatal, and cerebellar pathways, these findings have generally been small, and have not always been replicated”. They are specifically going to cite the problems with Rubia’s works, which we will cover in a second. What they are arguing is that there has not been enough consistency to say for certain. We see some abnormal patterns but it's only within a subgroup of individuals who have been diagnosed with ADHD, not all of the testing participants, and they argue that is not a reliable basis. They do state that “motor and timing deficits are not included within the diagnostic criteria for ADHD, they are increasingly recognized as common symptoms and have been identified as a promising area for future study”. So let's get into both Rubia and the timing studies.
Neural Networks
Rubia is essentially stating issues with ADHD are hypothesized to be more focused on neural networks
specifically “right and left hemispheric dorsal-ventral and medial fronto-cingulo-striato-thalamic and fronto-parieto-cerebellar network”
What’s a neural network? - We’ve hinted at this - one of the things humans struggle with, including this podcast, is the need to say x part of the brain does y. And we’ve tried to caveat this with ‘that’s an oversimplification’. Now, this podcast exists to simplify the brain - so it's no wonder we do this. But now we have to dive a bit more into the complexity that is neuro - To quote Dr. Sughrue “There are no areas solely responsible for complex functions like language, emotion, and attention, but multiple that are working in complex coordination - often presiding in completely different, non-adjacent parts of the brain. How they are connected is worth equal, if not more, attention, and together they form brain networks.” We hinted at this in the Neuroscience of Motivation - it's about what part of your brain is singing in harmony, rather than belting out a solo.
What’s hypothesized a lot for ADHD is that it's hard to understand because it focuses more on networks. The Dorsal Ventral and medial fronto-cingulo-striato-thalamic and frontal-parietal cerebellar network are helping with thought control, attention, timing, and what we call your working memory.
Dorsal Ventral - is attention processing
Specifically in a study, we saw reduced activation in this area for people diagnosed with ADHDnmedial fronto-cingulo-striato-thalamic - focused on movement execution, habit formation, and rewards
In ADHD what we see are potential issues with the white matter in this area in both here and in frontoparietal - intelligence, task switching, task adaptation, implementation, and flexibility in thought control
Orbital/Ventromedial
In addition, according to Rubia, there is emerging evidence for “abnormalities in
orbital and ventromedial prefrontal and limbic areas that mediate motivation and emotion control”
So Orbital and Ventromedial prefrontal cortex - from the neuroscience of depression - (this is literally just in front of your eyes)This is an area that is likely very important for rewards and punishments - left being reward and right being punishment. In ADHD what we see are abnormalities in this area, specifically evidence for a potential lack of cortical thickness, or delay in the maturation of this area
Studies were not specific here only stating that they say ‘abnormalities’ in this area for ADHD patients.
Lymbic
Lymbic - we talk about the Lymbic system all the time - because this is your happy middle child brain - specifically the super cliquy group of the hippocampus (brains filing cabinet) amygdala (brain’s alarm) and hypothalamus (brain’s thermometer) - and this has a pretty big role in the regulation of emotions, dealing with memories, and learning and gets very very impacted by stress. And we’ve had a few meta-analyses showing volume reductions in this area.
Dopamine
Slater and Tate Further specifically have a study focusing on timing. They are specifically citing Valera’s study that there are likely impacts to dopaminergic transmission. Dopamine impacts timing behavior. Noreika did a study 10 years ago that showed that methylphenidate, a drug that increases levels of dopamine reduced these timing deficits.
Timing is something we covered in the Neuroscience of Music. Dopamine we’ve covered a lot this season. Dopamine helps with musical rhythm. To quote Slater and TAte “Dopamine supports neural communication within reward, motor, and cognitive pathways and is involved in a wide range of functions including reward-based learning, motor coordination, and cognitive control”. It helps keep us in sync with the world around us. Slater and Tate argue that we need to take a great look at this, as it has promising results.
Body
Feel it on a scale of 1-Diagnosis (1-5)
This is a key one for the body right - because a lot of the time this is seen as trouble sitting still. It's like the body needs to be in movement all the time (at least with hyperactivity).
Inattentive has sometimes been described as more removed from the body - or distant, not present.
Behavior
Share examples
Warning sign
A lot of what we’ve already talked about. We usually assess for ADHD when we see someone having trouble paying attention, controlling impulsive behavior, or being overly active.
We want to learn WHY we do what we do as humans, and we’ve looked to the brain for explanations…
**BREAK**
PART 4: TAKEAWAYS (10-15 minutes)
Actions to support yourself or someone who thinks they may have ADHD - again this is not a diagnosis I treated and I’m cautious with it because it is so overdiagnosed.
I can say I have known one psychologist who I very much trusted - if she said you have it, you have it and it’s partially because she’s cautious and thorough - but specifically because she is a rarity amongst clinicians, (something all of us need to do so much better than we do) in which is she focuses on why you have your symptoms, not that you have them. - Her strength was approaching something from the patient’s perspective and getting into what was going on and why.
And I worked with her a lot, I think she’s one of the best clinical psychological testers I’ve ever seen. And some of the patients I saw her work with did get an ADHD diagnosis -but not all of them. This included a patient I had who the teachers swore the kid had ADHD, the primary care provider swore the kid had ADHD, the parents swore the kid had ADHD and the kid did not have ADHD.
ADHD is hard - because it does look like so many other things. And a lot of diagnoses do, which is why diagnosing is so tricky - but ADHD specifically.
But here’s the thing. What matters is not what you have so much as what works for you. What you have is a difficulty that should be honored and voiced. Something is making life harder than it should be. But does it matter if we call it Hyperkinetic Disease, or ADHD, or something else entirely? ADHD is treated primarily (in my limited experience) by medication and behavioral modification tools. I’m cautious of medication because I worked in a lot of environments where I saw adults who wanted kids medicated so much so they wouldn’t be loud, or active or a lot of work to regulate and focus. So you know, kids. Instead of adults. Right? So they wanted medication increased so that a 6-year-old would sit quietly in a corner all day.
But generally, if the medication works well for you, that’s often a sign. Medications are stimulants and if they act more like a depressive, that’s likely a sign something is not engaging as expected.
Behavioral modifications - I have seen a lot of these over social media. The pandemic made us all think we had ADHD. None of us could focus! None of us could pay attention. There was lots of trouble sleeping and staying on task. Hmm, shared trauma looks like ADHD. Just putting that out there. However, I saw a lot of helpful tips and tricks for managing ADHD. Ways to organize, ways to stay on task. If you see those and they work for you - great! Use them. If you see them and they work for your kids - great! Use them! You don’t need a diagnosis to get benefits from these - it doesn’t make them more or less valid for you. Use what works for you. Because we all need things from time to time to make life a little more manageable.
If you feel like you have the symptoms of ADHD, you likely do. It doesn’t mean you have the diagnosis. Honestly, even if you have the diagnosis it doesn’t necessarily mean you have ADHD.
