ADHD (Attention Deficit Hyperactivity Disorder) is currently the most frequently diagnosed psychiatric “illness” among young North Americans.
Eleven percent of them receive this diagnosis at least once between the ages of 4 and 17. The number of diagnosed cases and treatments has increased so much in the last decade that one might wonder if something affecting so many people truly constitutes a disease; and rightly so!Recent neuroscience research shows that individuals with ADHD are brain-programmed to seek novelty: a characteristic that, until recently (a few thousand years ago), represented an evolutionary advantage. Compared to others, the reward circuits in the brains of people with ADHD are under-stimulated by a routine and unstimulating daily life.
To compensate, people with ADHD are drawn to new and exciting experiences. They are known for their impatience and restlessness in reaction to the constraints and procedures that characterize our modern world. In short, people with ADHD don't so much have a disorder as a set of behavioral traits that don't align with the expectations of our contemporary culture.
From the perspective of teachers, parents, and the world at large, children with ADHD experience problems that manifest as a lack of concentration and attention, and impulsive behavior. But if you have this "condition," the real issue is that your brain perceives a fundamentally uninteresting world around it.
One of my patients, a young woman of 20, is typical. "I was on Adderall (Amphetamine) for years to help me concentrate," she told me during our first interview.
Before taking Adderall, she couldn't stand sitting in meetings and would lose focus within minutes. Like many people with ADHD , she sought out interesting and varied experiences to alleviate boredom and also turned to alcohol. But when she encountered something new and stimulating, she was able to concentrate remarkably well. I knew she enjoyed painting, and I asked her how long she could maintain her focus while working with her palette and brushes. She told me she could paint for hours on end without any problem.
“Rewards” like sex, money, drugs, and novel situations all trigger the release of dopamine in the brain’s reward circuits, a region buried deep beneath the cortex. Beyond the feeling of pleasure, this dopamine signal tells your brain something like, “Pay attention, this is an important experience to remember.” The more novel and unpredictable the experience, the more activity increases in your reward center.
But what is stimulating for one person can be boring, unbearable, or, conversely, thrilling for another. There is great variability in the sensitivity of this reward circuit. Clinicians have long observed this, and everyday experience demonstrates it. Think of adrenaline junkies who bungee jump without breaking a sweat and compare them to anxious spectators for whom this experience evokes only terror and dread!
Dr. Nora D. Volkow, a scientist who directs the National Institute on Addiction, studied the dopamine reward pathway in people with ADHD . Using a PET scan, she and her colleagues compared the number of dopamine receptors in this brain region in a group of adults with untreated ADHD to that of a group of healthy controls. What she found was striking. Adults with ADHD had significantly fewer D2 and D3 receptors (two subtypes of dopamine receptors) in their reward circuits than those without ADHD . Furthermore, the lower the level of dopamine receptors, the more pronounced the subjects' symptoms of inattention. Studies in children have shown similar changes in dopamine function.
These results suggest that people with ADHD have reward circuits that are less sensitive to inclusion than those of the rest of us. Having an underactive reward circuit makes normally interesting activities seem dull and partly explains why people with ADHD find repetitive and routine tasks unrewarding and even painfully boring. Psychostimulants like Adderall and Ritalin help people with ADHD by blocking the reuptake of dopamine around their neurons, thus increasing its level in the brain.
Another of my patients, a 28-year-old man, was suffering greatly at his job in an advertising agency. Sitting at a desk for long hours and concentrating his attention on a file was almost impossible.
He was multitasking, listening to music and texting, "working" to escape the routine. Eventually, he left his job for a startup, which put him in a constantly changing environment. He's much happier and—surprise, surprise—has lost his ADHD symptoms. My patient simply "treated" his ADHD by swapping his highly routine work environment for one that was more varied and less predictable. Suddenly, his biggest flaws—impatience, short attention span, and restlessness—became strengths, and I think this finding is fundamental to understanding what goes on in ADHD . Humans evolved over millions of years as nomadic hunter-gatherers.
It was when we invented agriculture, around 10,000 years ago, that we settled down and began to live a more sedentary and boring life. Before that, as hunters, we had to adapt to a constantly changing environment where dangers were as unpredictable as the time of our next meal.
In such a context, a short, fluctuating, and intense attention span, along with a thirst for discovery, constituted a selective advantage. This profile facilitated the location and securing of "rewards," such as a mate or a prime piece of mastodon meat. In short, what we now call ADHD would have made you a champion in the Paleolithic era.
In fact, we have modern evidence to support this hypothesis. In Kenya, there is a tribe called the Ariaal, animal herders who were traditionally nomadic. More recently, a subgroup seceded and settled down to practice agriculture.
Dr. Dan Eisenberg, an anthropologist at the University of Washington, compared the frequency of a genetic variant of the type 4 dopamine receptor called DRD4 7R in nomadic and sedentary Ariaal groups. This genetic variant decreases the receptor's sensitivity to dopamine and is specifically linked to ADHD .
Dan Eisenberg discovered that nomads carrying the DRD4 7R variant were better nourished than nomads without it. But what was striking was the opposite finding for Ariaal farmers: those carrying this genetic variant were significantly leaner than the others. So, if you're a nomad, having a gene that promotes ADHD-like behaviors is clearly advantageous (you're better nourished), but the same trait is a disadvantage if you live in a sedentary environment. It's not hard to understand why nomadic Ariaal, with their heightened attention span and thirst for adventure, are likely to fare better in a constantly shifting and unpredictable environment, especially when it comes to finding food. But that same short, intense attention span wouldn't be very helpful to farmers, who need to focus on activities that require sustained attention, like going to school, managing crops, and negotiating their harvests.
You may be wondering what explains the recent explosion in the number of ADHD diagnoses?
According to the (US) Centers for Disease Control and Prevention, its prevalence among children rose to 11% in 2011, compared to 7.8% in 2003, an increase of 41%, which is enormous. Furthermore, 6.1% of young people were taking medication for ADHD in 2011, a 28% increase since 2007. Even more alarming: at least 10,000 children aged 2 and 3 are taking these medications, far exceeding official pediatric recommendations.
The pharmaceutical industry is undoubtedly responsible for part of the increased prevalence of ADHD , as its treatments are profitable for them. Some blame the increased workload at school, but the data doesn't support this. All studies show that the number of hours of homework for high school students has remained stable for 30 years. I think another social factor that may contribute, at least in part, to the ADHD "epidemic" has gone unnoticed.
This refers to the increasingly stark contrast between the disciplined and demanding school environment and the highly stimulating digital world where young people spend their time outside of school. This digital life, with its online games and engaging social media, represents a world of instant gratification where virtually any whim or desire can be fulfilled in the blink of an eye. By comparison, school seems even more bland to a modern, stimulation-hungry child than it did in previous decades. This comparatively more boring school environment could exacerbate students' inattentive behavior, leading to an increase in diagnoses under pressure from teachers and those around them.
Fortunately, there is some good news. Interestingly, the prevalence of ADHD in adults is only 3 to 5%, a fraction of what it is in young people. This suggests that a significant number of people with ADHD simply "recover" from their condition.
Why? Perhaps because adults have much more freedom to choose the environment in which they live and pursue a career that better aligns with their aspirations and the cognitive rewards they seek. If you're a restless child who can't sit still at school, you might become an entrepreneur or a carpenter, but you're less likely to end up as a chartered accountant.
What could possibly be happening in the brain of people with ADHD that could explain this spontaneous "recovery"?
To try to answer this question, Aaron T. Mattfeld, a neuroscientist at the Massachusetts Institute of Technology (MIT) currently working at Florida International University in Miami, used MRI to compare the resting-state brain function of three groups of adults: * Individuals with ADHD whose symptoms persist into adulthood; * Individuals with ADHD who have "recovered"; * Control subjects without ADHD. Normally, when someone relaxes and is not focused on a task, brain regions known as the Default Mode Network synchronize, and these regions are generally more active during rest than while performing a task. In contrast, in individuals with ADHD, these regions appear to be functionally disconnected from each other during rest. Dr. Mattfeld found that the adults with former ADHD who had "recovered" showed a restoration of normal synchronization: their brains behaved like those of the control subjects without ADHD.
We don't yet know whether these brain changes preceded or followed the improvement in their behavior, so the exact mechanism of the adults' recovery is unclear. Furthermore, in another synchronicity study, an MIT study found that the brains of the adults who had recovered more closely resembled those of adults with ADHD than those of the control group.
In individuals without ADHD, when the Default Mode Network is activated, another network, called the Positive Task Network, is inhibited. When the brain focuses, the Positive Task Network takes over and puts the Default Mode Network to rest. This reciprocal relationship is necessary for concentration. However, both groups of adults with ADHD, including those who had recovered, showed simultaneous activation of both networks, as if these two networks were operating in opposition. Thus, the brains of adults who lost most of their symptoms did not fully recover normal activity.
What are the implications of this new research on how we understand and treat children with ADHD?
Of course, I'm not saying we should take our children out of school and send them to the savanna. Nor am I saying we should stop using stimulant medications like Ritalin or Adderall, which are safe, effective, and very helpful for many children with ADHD. But perhaps we could help these children by drawing on the experience of adults who have recovered from their symptoms. First, we should do everything we can to help young people with ADHD select educational environments or career paths that best suit their thirst for discovery, just as adults seem to choose jobs in which they are more likely to succeed.
At school, these curious and experience-seeking children would likely thrive in small classes that emphasize hands-on activities, missions and tasks that reinforce their specific ADHD skills, and computer-assisted self-directed learning that adapts to their pace. This won't eliminate the need for many children with ADHD to take psychostimulants. But let's not rush to medicalize their curiosity, energy, and thirst for novelty; in a supportive environment, these traits are not a handicap; on the contrary, they can be a real asset.
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