According to the most authoritative data at the time of this writing, approximately 8% of children in the United States, aged 4 to 17, have been diagnosed as having ADHD (Attention Deficit Hyperactivity Disorder). The same reports note that the disorder is about 3 times as frequent in boys as it is in girls, so this means that roughly 12% of boys and 4% of girls have received the diagnosis.
Think of it. Twelve percent of boys—that's approximately one boy out of every eight—have been determined by some clinical authority, using official diagnostic criteria set out by the American Psychiatric Association, to have this particular mental disorder. [Note added in June, 2015. Now things have gotten worse. According to the latest data, now 20% of boys are diagnosed with ADHD at some point in their school career.]
If only teachers' ratings were used, the numbers would be even greater. In one study involving 16 different schools and more than 3,000 children, teachers filled out the standard ADHD diagnostic checklist of behaviors for the students in their classrooms. In that study, where teachers' ratings were not averaged in with the ratings made by parents, 23% of elementary school boys and 20% of secondary school boys were diagnosed as having ADHD. What an amazing finding. By teachers' ratings, nearly one fourth of all elementary school boys and one fifth of all secondary school boys has the mental disorder ADHD.
ADHD Is Fundamentally a School Adjustment Problem
What does it mean to have ADHD? Basically, it means failure to adapt to the conditions of standard schooling. Most diagnoses of ADHD originate with teachers' observations. In the typical case, a child has been a persistent pain in the neck in school—not paying attention, not completing assignments, disrupting class with excessive movements and verbal outbursts—and the teacher, consequently, urges the parents to consult with a clinician about the possibility that the child has ADHD.
Using the standard diagnostic checklists, the clinician then takes into account the ratings of teachers and of parents concerning the child's behavior. If the ratings meet the criterion level, then a diagnosis of ADHD is made. The child may then be put on a drug such as Adderall or Concerta, with the result, usually, that the child's behavior in school improves. The student begins to do what the teacher asks him to do; the classroom is less disrupted; and the parents are relieved. The drug works.
The diagnostic criteria for ADHD, as outlined by DSM-IV (the official diagnostic manual of the American Psychiatric Association), clearly pertain primarily to school behavior. The manual lists nine criteria having to do with inattention and another nine having to do with hyperactivity and impulsivity. If a child manifests at least six of either set of nine, to a sufficient degree and over a long enough period of time, then the child is identified as having one or another version of ADHD. Depending on which set of criteria are manifested, the child is given a diagnosis of ADHD Predominantly Inattentive Type; ADHD Predominantly Hyperactive-Impulsive Type; or ADHD Combined Type.
Here, for you to peruse, are the complete lists of criteria, quoted directly from DSM-IV:
- Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
- Often has trouble keeping attention on tasks or play activities.
- Often does not seem to listen when spoken to directly.
- Often does not follow instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).
- Often has trouble organizing activities.
- Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period of time (such as schoolwork or homework).
- Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books, or tools).
- Is often easily distracted.
- Is often forgetful in daily activities.
Hyperactivity & Impulsivity
- Often fidgets with hands or feet or squirms in seat.
- Often gets up from seat when remaining in seat is expected.
- Often runs about or climbs when and where it is not appropriate (adolescents or adults may feel very restless).
- Often has trouble playing or enjoying leisure activities quietly.
- Is often "on the go" or often reacts as if "driven by a motor."
- Often talks excessively.
- Often blurts out answers before questions have been finished.
- Often has trouble waiting one's turn.
- Often interrupts or intrudes on others (e.g., butts into conversations or games).
OK, after reading this list, who is surprised that so many boys have been diagnosed as having ADHD and that teachers usually initiate the diagnostic process? Raise your hand (but please don't blurt out your answer before I call on you).
How convenient that we have this official way of diagnosing kids who don't sit still in their seats, often fail to pay attention to the teacher, don't regularly do the assignments given to them, often speak out of turn, and blurt out answers before the questions are finished. They used to be called "naughty"—sometimes with a frown, sometimes with a smile of recognition that "kids will be kids" or "boys will be boys"—but now we know that they are, for biological reasons, mentally disordered.
Wonder-of-wonders, we even have an effective treatment. We can give them a powerful drug—a preparation of methylphenidate or amphetamine, both of which have effects on the brain similar to those of cocaine (but without the euphoria) and are, for good reasons, illegal to take unless you have been diagnosed with a mental disorder and given a prescription. The drug works. The children become more tractable and classroom management becomes easier.
The most common subtype of ADHD is the Predominantly Inattentive Type. This is the disorder that used to be called just ADD. A highly respected pediatrician at Yale University who treats (with drugs) many children diagnosed with this disorder made this interesting confession:
"A disproportionate number of children labeled ‘ADHD without hyperactivity' are exceptionally bright and creative children. I've often thought that these kids find their own inner theater much richer and more interesting than the outer theater of the classroom and, so, naturally, focus on it at the expense of classroom attention ... The proper fix for this problem would be done at the school level, a place where I am unlikely to have any significant effect. I can, however, help these children concentrate and return their attention to the classroom."
Why Do So Many Kids Have Difficulty Adjusting to School?
From an evolutionary perspective, school is an abnormal environment. Nothing like it ever existed in the long course of evolution during which we acquired our human nature. School is a place where children are expected to spend most of their time sitting quietly in chairs, listening to a teacher talk about things that don't particularly interest them, reading what they are told to read, writing what they are told to write, and feeding memorized information back on tests.
As I have detailed in previous essays, during the entire course of human history until very recently, children were in charge of their own education. They learned by following their own inner, instinctive guides, which led them to ask countless questions (their own questions, not someone else's), converse with others as equal partners, explore their world actively, and practice the skills crucial to their culture through self-directed play in age-mixed groups. [See Children Educate Themselves II: The Wisdom of Hunter-Gatherers.]
From my evolutionary perspective, it is not at all surprising that many children fail to adapt to the school environment, in ways that lead to the ADHD diagnosis. All normal children have at least some difficulty adapting to school. It is not natural for children (or anyone else, for that matter) to spend so much time sitting, so much time ignoring their own real questions and interests, so much time doing precisely what they are told to do.
We humans are highly adaptable, but we are not infinitely adaptable. It is possible to push an environment so far out of the bounds of normality that many of our members just can't abide by it, and that is what we have done with schools. It is not surprising to me that the rate of diagnosis of ADHD began to skyrocket during the same decade (the 1990s) when schools became even more restrictive than they had been before—when high-stakes testing became prominent, when recesses were dropped, when teachers were told that they must teach to the standardized tests and everyone must pass or the teachers themselves might lose their jobs.
Schools' Intolerance of Normal Human Diversity
Why do some kids adapt to school better than do others? The answer to that does lie in biology—normal biology, not abnormal biology. For good evolutionary reasons, members of our species vary genetically in ways that create diversity in personality. People have always lived in communities, and communities—as well as the individuals within them—benefit from diversity.
It is good that some people are relatively restrained while others are more impulsive, that some are relatively passive while others are more active, that some are cautious while others are bolder, and so on. These are among the dimensions that make up normal personality. In situations where people are free, they find ways of behaving and learning that fit best with their biological nature, and through those means they make unique contributions to the communities in which they live. Normal human environments always have a variety of niches that people can occupy, and people who are free naturally choose niches where they are most comfortable and happy, the niches that match best with their biological nature.
But school, especially today, does not have a variety of niches. Everyone is expected to do the same thing, at the same time, in the same way. Everyone must pass the same tests. Some people, apparently most, have a personality that allows them to adapt sufficiently well to the school environment that they pass the tests and avoid behaving in ways that the teachers can't tolerate. School may take its toll on them, but the toll is not so obvious. The toll may manifest itself as diffuse anxiety, or moderate depression, or cynicism, or suppression of self-initiative and creativity; but the school system can absorb all that. Those characteristics become viewed as "normal." Unless they become really extreme, they don't get DSM-IV diagnoses. It's the kids whose personalities do not allow them to go along with the system who get the ADHD diagnoses. And most of those are boys.
One of the biological characteristics that predisposes for ADHD in the school environment, obviously, is the Y chromosome. For evolutionary reasons, boys are, on average, more physically active, more adventurous (in the sense of taking risks), more impulsive, and less compliant than girls. A normal distribution of such traits exists for both boys and girls. The distributions overlap considerably, but are not identical. The cutoff on the distribution that gets you a diagnosis of ADHD in our present society happens to be at a point that includes about 12% of boys and 4% of girls. In another setting, where they could choose their niches, most of those kids would do just fine.
An Illustrative Story
I'll conclude with a true story to illustrate all this. It pertains to a young man whom I have known well since he was 13 years old. Throughout his school years, he was funny, playful, extraordinarily impulsive, and a huge pain in the neck to essentially all of his teachers. He rarely completed a school assignment and was constantly disruptive in class. He truly could not focus on any of his school lessons and he seemed unable to prevent himself from saying what was on his mind rather than what he was supposed to say.
His parents were regularly called in for conferences. When school officials asked his parents to take him to a clinic for an ADHD diagnosis, his mother—a physician who knew that the long-term brain effects of the drugs used to treat ADHD have never been tested in humans and have proven deleterious in laboratory animals—refused to do so.
The boy had all the characteristics of ADHD Combined Type, and I have no doubt that he would have received that diagnosis had his mother consented. Thanks to a relatively lenient and understanding assistant principal, he was passed along from grade to grade, even though he did almost none of the assigned work and failed most of his tests. He graduated from high school at the bottom of his class.
Then, the good part of his life began. Clearly unfit for college, he did a year in an internship program and discovered that he enjoyed cooking and was good at it. After working in a restaurant for a while, he received recommendations that got him into a culinary school, where he loved the work and excelled.
Now, at the age of 22, he has an excellent job as assistant to the chef in a very busy, very successful restaurant. In this setting, which requires constant, active, hands-on work and the kind of mental brilliance that involves attending to and responding to many competing and immediately demanding sources at once, he shines. He has found his niche. He learned nothing from his 13 years of public schooling, but, because of his buoyant personality, school did not destroy him. When he was finally out of school, free to pursue his own interests in the real world, he found his niche and now is thriving there. The real world, thank goodness, is very different from school
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 For ADHD prevalence data, see: Vissar et al. (Feb., 2007), Pediatrics 119, S99-S106; Centers for Disease Control and Prevention (Sept. 2, 2005), "Mental health in the United States: Prevalence of Diagnosis and Medication Treatment for ADHD," MMWR: Morbitidy and Mortality Weekly Report 54, 842-846; and Mayes et al (2009), Medicating Children: ADHD and Pediatric Mental Health (Harvard University Press), p 2.
 Nolan et al. (2001), Teacher reports of DSM-IV ADHD, ODD, and CD symptoms in schoolchildren. Journal of the Academy of Child and Adolescent Psychiatry, 40, 241-249.
 See Mayes et al., p 4.
 In order to make ADHD not appear to be just a school problem, DSM-IV adds the stipulation that the symptoms must be seen in at least one other setting, not just in school. However, it does not stipulate that the other setting has to be radically different from school. It is easy to see how parents, after being convinced that their child has ADHD from the school reports, might "see" such symptoms at home or in another setting--especially while doing homework, or when involved in some adult-directed activity such as lessons or formal sports outside of school. Nevertheless, the failure of these symptoms to manifest themselves so much in settings outside of school probably explains why rates of ADHD diagnoses based just on teacher reports are so much higher than those based on a combination of teachers' and parents' reports.
 Sidney Spiesel, quoted by Mayes et al., p 12.
 For a documented discussion of the evolutionary foundation for diversity in personality in humans and other species see P. Gray (2010), Psychology, 6th Edition, pp 560-570