Attention Deficit Hyperactivity Disorder. A friend recently pointed out that the very name of the disorder stems from the “publicly negative” aspects of ADHD. Like most mental disorders, ADHD runs deep. Small attention spans, and high bursts of activity do characterize ADHD, but so does forming new relationships too quickly, Sensory Processing Disorder (SPD), and substance abuse. Interestingly, this disorder’s diagnosis rate is up to 13%, making it perhaps the most common chronic disorder. Yet, despite its prevalence, ADHD remains deeply misunderstood—lets explore this fascinating disorder.
I am preparing a series about the evolutionary advantages of chronic mental disorders with a high diagnosis rate. Of all qualifying disorders, ADHD may provide the strongest benefit to the diagnosed individual. However, the “What is X Disorder Really?” sub-series means to focus on diverse, factual information. Let me leave you with a thesis statement as a teaser: ADHD only constitutes a disorder in a primarily sedentary society and educational system.
To grossly oversimplify the disorder, and jump to conclusions of continued research, ADHD primarily results from either reduced dopamine levels or some deficiency in processing dopamine. As one of the primary chemicals involved in the brain’s reward and learning systems, dopamine and reward-related behavior correlate heavily. Again, this description disgustingly oversimplifies the complex biochemistry and neural physiology behind ADHD. I have written a more detailed description of current research on ADHD later in the article, but this explanation will suffice for most of the article.
Fun fact: DSM-5 no longer recognizes Attention Deficit Disorder (ADD); ADHD now includes what used to be ADD, and ADHD classification contains three presentations—Combined Presentation, Predominantly Inattentive Presentation, and Predominantly Hyperactive-Impulsive Presentation—based on an individual’s specific symptoms.
Attention Deficits and Sensory Processing Disorder
We’ve all heard the trite trope of having the attention…SQUIRREL! Bland jokes aside, people with ADHD really do have reduced attention spans. We’ve known for decades that dopamine plays a role in regulating attention. A topic that interests you stimulates your reward pathway, and one that doesn’t, doesn’t. However, people without ADHD can force themselves to maintain attention despite losing interest. Importantly, the conversation doesn’t have to be boring for someone with ADHD to lull off, it simply needs to generate less dopamine than competing stimuli, i.e. don’t take it personally if someone with ADHD zones out of the conversation or gets distracted. I do not mean to paint an image of someone with ADHD chasing the highest local dopamine source. Reduced attention regulation does not constitute a complete inability to manage one’s focus. In fact, reduced attention spans result in unique and nuanced side effects.
Attention regulation may cause SPD, but one of many common co-morbid disorders with ADHD. In brief, a person has SPD when they cannot successfully process multiple simultaneous stimuli. When one’s attention constantly shifts, due to low dopamine, a new stimulus comes as a surprise, and too many surprises overwhelm the sufferer. The stimulus may be new or changing; let’s use two examples to demonstrate:
While playing in a clear public pool, you get splashed in the back by some rowdy kids. Hundreds of variably sized droplets ripple across your skin with pseudo-random timing. Thousands of nerves send pulses to your parietal lobe, communicating vast quantities of information. Most brains filter out a lot of the noise, registering the overall sensation as a splash. But you have ADHD. Rather than filtering the information, your brain desperately tries to react to and process each signal. Instead of just noting a splash, you become irritated and even angry.
You’re wearing a new bright green shirt to showcase your deep brown socks and marbled pants (I should never be allowed to work in the fashion industry). However, the manufacture chemically treated your shirt to reduce wrinkling, and prevent microbial growth. Most people can’t physically feel the treatment, or may not mind the tactile sensation. But you have ADHD. You walk down the hallway, and the shirt moves against your skin. That chemical coat itches as it runs across your body. Every step shifts your shirt and sends a new wave of discomfort. You’re basically writhing, trying to remove that itchy film. However, you can’t stop the flood of neural signals, and eventually change to a washed shirt.
Many people with SPD share a common set of distasteful stimuli. Reactions to these stimuli range from simple dislike to strong emotions, such as anger or fear:
- Unexpected touches
- Seams of socks
- Certain foods
- Loud gatherings
In general, ADHD-SPD makes people hyper-aware of tactile and auditory stimuli. Not all sensations cause negative reactions; being hyper-aware also leads to desiring certain textures or sounds. Diagnosed individuals may really enjoy hugs, roller coasters (a plane falling during turbulence fills me with childlike glee), and textured cutlery. Exploring complex, but planned, stimuli often pleases those with SPD and helps them when learning. Personally, my hands rarely empty as I find new pens, coins, or most anything around me to explore. Attention regulation inhibitions result in complicated side effects reaching far beyond conversational steadfastness.
Hyperactivity and Perservation
Hyperactivity in ADHD is…weird. That’s one way to write a topic sentence, eh? People with ADHD have reduced dopamine in their neural synapses, but hyperactivity and impulsivity—hallmarks of ADHD—more readily correlate with increased dopamine. Dopamine levels above what’s needed to encourage a behavior basically put you into a state of constant reward, lowering the impetus requirement of activity—as a point of reference, cocaine greatly increases dopamine levels. It took me a long time to find a satisfactory answer to this dilemma. A paper published last month in Cell Reports revealed a few genes influencing hyperactivity in mice. These genes code for synaptic adhesion proteins—molecules that hold the ends of two nerves together—and control the ratio of excitatory to inhibitory connections within dopamine-responsive neurons. Interestingly, previous studies also linked these genes to schizophrenia and OCD. Mice with ADHD-symptoms have different ratios of these connective proteins compared to mice without any symptoms. This means that the ADHD brain responds differently to dopamine, namely low levels of dopamine still trigger hyperactivity. However, ADHD medications increase dopamine concentration in the brain, which mitigates both the attentive and hyperactivity components of ADHD. Given my above interpretation, more dopamine in a neural circuit that can interpret low dopamine as a hyperactive signal should skyrocket hyperactivity past the Oort cloud. However, many simultaneous signals control whether any given neuron fires, so the increase in dopamine via medication may cause unknown effects reducing the hyperactive response. There’s also a strong possibility that I’ve missed something in my research. So, yeah, hyperactivity in ADHD is weird. Moving on!
After writing the above paragraph, I became really curious about people with ADHD on cocaine. Google Scholar came back with over 34,000 results. It appears that, predictably, cocaine’s dopamine increase dramatically outweighs the dopamine deficit in ADHD brains. Impulsivity leads to drug addiction, and then the two become difficult to treat. Don’t self-medicate with cocaine kids!
Fascinatingly, the mechanisms underlying attention deficits and impulsivity also create a powerful phenomenon: hyperfocus/perservation. To reiterate the above, ADHD brains may respond to low levels of dopamine with hyperactive/impulsive behaviors, and also respond strongly to external rewards. Attention deficits also lead to hyper-awareness of one’s surroundings, as their attention flits about the environment. Now imagine your fixing something under the hood of your car. Literally hundreds of parts fill your vision; each interlaced into a powerful web of activity. Once you’ve identified the problem, you need to remove several parts, fix the issue, and put everything back together. Every movement, part, and action becomes a new focus point. This may sound overwhelming, but having so many points of interest within a coherent network and task starts to hyperfocus one’s attention. Let’s perform an exercise together:
- Close your eyes and wait a few seconds.
- Visualize yourself lying in an empty field with a thousand twinkling stars across the entire night sky above you.
- Whenever a star winks, immediately give it your full attention until the next star blinks.
- Mindfully continue this pattern for about twenty seconds.
- Now coalesce the stars into a single region. Build them into a constellation.
- Whenever a start twinkles, immediately give it your full attention as before.
- Follow the lights for about twenty seconds.
- Note what changed between step 3 and step 7.
- What was in your peripheral vision when the stars were spread out versus in a constellation?
- How far did you have to move your head to track blinks between the two steps?
- Recall looking at a star on the far left side of your field of view. When the stars were distributed, would you have missed a twinkle on opposite side of the sky? Would you have missed a star flashing on the right when they were all in a constellation?
The constellation models perservation well: all the interesting pieces remain in one plane, and thus a single focal point satisfies the whole. In effect, it becomes a pinball machine where one’s attention may bounce rapidly, but it stays within a single region and performs a single larger function. People with ADHD can perservate due to over-stimulus or stress, or may hyperfocus on activities of interest to themselves. Typically perservation has a tunneling effect: one task consumes all your attention, and thus everything else disappears. Snapping someone out of a hyperfocus state can literally feel like rapidly zooming out of a macro shot, and can be quite jarring—even scary. However, an ADHD brain in hyperfocus mode can accomplish work at an exhilarating pace and excels at technical work. Some of the best technicians, programmers, and engineers have ADHD.
For The Trees
I wrote my favorite piece of code ever in a state of perservation (lines 96–154). The code doesn’t merit any technical praise whatsoever—I’m 100% an amateur coder. Rather, it’s my favorite code because of how it came into existence. I was starting on a project at work and began to write some code to organize and track some data. Figuring out how to link the data within the system I made became a huge challenge, and I began perservating. About 30 minutes later, I had a eureka moment when the function finally reported the data back in the format I needed. Triumphant, I took a break, and then sat back down to review my work. I did not recognize the code at all. The next 30 minutes consisted of me figuring out what I wrote, and how the hell it worked.
Hyperfocusing empowers people with ADHD, but can also cause immense stress. When perservating, a person may refuse to leave a topic during a conversation. You might discuss a computer with a coworker, but then the conversation naturally transitions to a problem at work. However, your perservating on the computer, and keep bringing it back up—almost forcibly at times. Sadly, this state is difficult for the sufferer to recognize and even harder to stop even if you consciously know you are currently hyperfocusing. Perservation episodes can also cause obsessive-compulsive behaviors. A child might have misplaced a shoe, but now needs to find it before leaving for school. The shoe isn’t in its usual spot, and they have a time constraint. Said child repeatedly checks the same four places where their shoe “must be.” Even if the child recognizes that their perservating, they will continue to primarily only check those same four spots as stress builds. Like many aspects of ADHD, what empowers also stings.
Research and Conclusion
While the exact cause of ADHD remains unknown, substantial ongoing research continues to uncover its mysteries. Based on twin studies, we know that genetic variance explains up to 74% of cases. Environmental factors, such as certain chemicals may cause ADHD if encountered at a young age, e.g. infants with a Fetal Alcohol Spectrum Disorder may develop ADHD. A literature review in 2010 correlated lead and PCB exposure to the prevalence of ADHD. In a textbook from 2018, an entire chapter summarizes current knowledge about the structure of an ADHD brain. Both the cortico-striatal-thalamic-cortical circuit (CSTC) and the corpus callosum may have reduced organization compared to a control group. If you’re an avid reader of this blog, you may have heard of the CSTC before: it is implicated in OCD. The corpus callosum contains some 300 million axons, and connects the two hemispheres of the brain—on a complete aside, do yourself a favor and read the Wikipedia page about Dual Consciousness, a phenomenon that occurs after you sever the corpus callosum in two, it still keeps me up at night. Among other regions, this bundle of neural fibers connects the areas of the brain responsible for motor function and sensory processing. Many of these studies and reviews occurred only in the last few years; continuing efforts to understand ADHD will continue to uncover invaluable insight into this extremely common disorder.
ADHD truly mystifies the mind with complex neurophysiology and seeming contradictions. We haven’t even touched on this disorder’s effect on working memory, public education, romantic relationships, addiction, obesity, and so much more. Once you understand the fundamental differences in an ADHD brain, you begin to see it woven throughout the tapestry of one’s life. Given its prevalence, and possible benefits, ADHD serves as a bridge between the general public and mental health. Mental health education can bring along a doom and gloom atmosphere that alienates listeners. However, conversations concerning this disorder can very easily leave on a high note. Furthermore, everyone can benefit from the discussion as, statistically speaking, everyone likely knows several people with ADHD. Far from dismissable, Attention Deficit Hyperactivity Disorder significantly impacts one’s life in a unique and meaningful way.
Have a great day and always practice self-compassion!A Fantastic Friend of Mine