The difficulty of identifying ADHD in children
Diagnosing ADHD, or attention deficit hyperactivity disorder, is intrinsically problematic.
The symptoms—distractibility, impulsivity, and hyperactivity—are consistent with the normal behavior of young children.
So when a child is diagnosed, the implication is that he is more distractible, impulsive, or hyperactive than he should be for his age.
But where do we draw the line between developmentally normal behavior and medical disorder?
That's a crucial question because diagnosis rates among very young children are on the rise, and many kids are being medicated.
According to historical health data collected in the United States, the percentage of 2-to-5-year-olds diagnosed with ADHD increased by 50% between 2008 and 2012 (Danielson et al 2017).
And a study by the U.S. Center for Disease Control indicates that children diagnosed in this age group are more likely to receive prescription medication than the go-to, first-line treatment recommended by the American Academy of Pediatrics: behavioral therapy (Visser et al 2016).
Here I review current ideas about ADHD in children, including reasons for doubt.
It's not a comprehensive account of ADHD, and it's not meant to deny that some kids suffer from important attention or hyperactivity problems. If you think your child might have ADHD, you should discuss your concerns with a physician.
But the following account provides an overview of the reasons why parents of young children should exercise a healthy skepticism before accepting a diagnosis of ADHD. I raise these points:
• The official definition of ADHD in children is based on subjective criteria. To get diagnosed with ADHD, a child's symptoms should be bothersome--so much so that she has trouble functioning at school or in other social settings. But who sets the standards that kids must meet to be considered normal?
• Expectations about kids have probably changed over the decades. In Britain, all kids begin formal schooling at the age of 4. In the United States, kindergarten is becoming more academic. But in many traditional cultures, people don't expect much self-discipline from children until they are 6 or 7.
• Throughout the world, ADHD is being overdiagnosed. International studies suggest that some kids are being diagnosed with ADHD because they are young or immature for their assigned grade level, not because their behavior falls outside the range of normal development.
• Biomarkers don't prove that a person needs drugs. Kids diagnosed with ADHD are more likely to carry certain genes and exhibit certain brain chemistry profiles. But we can probably say the same about kids who are shy, or aggressive, or perennially cheerful. Genes and neurotransmitters influence all sorts of behavior. That by itself doesn't make behavior pathological or worthy of medication. The decision to medicate should be based on a careful weighing of factors, including the severity of the symptoms, and the costs and benefits of taking the drug. Side effects may render the costs too high.
• ADHD isn't the only cause of distractibility or hyperactivity. ADHD-like symptoms may be caused by a variety of conditions, including sleep disorders, anxiety, and poor working memory skills. If there is a rush to attribute a child's problems to ADHD, alternative treatments could get overlooked.
Attention deficit disorder, or ADHD, has been defined as "the co-existence of attentional problems and hyperactivity"
According to the American Academy of Child Adolescent Psychiatry (AACAP), this means a child who
If you think ADHD symptoms sound like the description of a normally-developing preschooler, you're right.
Virtually everybody shows these "symptoms" when they are two, three, or four years old.
And different kids develop at different rates. Some take a little longer to focus their attention and restrain their impulses.
On average, though, most kids seem to settle down between the ages of 5 and 7. And this age range is recognized worldwide. It's called the "5-to-7" transition, the period during which young children begin to show more "executive control," i.e., improved abilities to plan ahead, think abstractly, focus attention, and inhibit inappropriate behavior.
Along these lines, it's interesting to reflect on the results of a study conducted in Sweden. Researchers screened 422 first graders for signs of ADHD by asking parents and teachers to answer a standard, ten-point questionnaire (the "Conners 10-item scale").
Three years later, they checked on the kids' progress.
Did the early screening predict which children would receive a formal diagnosis of ADHD in the fourth grade?
It did, but with a big margin of error. The very best predictor--which was a combination of high scores from both parents and teachers--had a positive predictive value of 50%, meaning that only half the children who screened positive for ADHD in the first grade ended up with a formal diagnosis in the fourth grade (Holmberg et al 2013).
Around the world, societies show remarkable agreement. Kids aren't expected to show much self-discipline until they reach the 5-to-7 transition.
In a famous study, psychologist Barbara Rogoff and her colleagues reviewed 50 different cultures to discover when ordinary people think kids are capable of self-control and ready to meet responsibilities (Rogoff et al 1975).
The researchers considered a wide array of criteria, including these:
The results suggest that regular people don't demand much executive control from young children.
The majority of societies surveyed didn't expect to observe common sense and rationality before the age of 6.
In most places, kids weren’t even asked to play rule-based games until they were at least 6.
And the most common age at which people began making a special effort to teach kids social rules? 7.
So it seems awkward to try to diagnose a child with ADHD while he's still in preschool, or even first grade. Behavior that is entirely normal and age-appropriate might get labeled as ADHD.
But unfortunately, it's not unusual for kids to get diagnosed at an early age.
Indeed, according to the AACAP, a child shouldn't be diagnosed with ADHD unless his symptoms emerge before the age of 7.
Are the symptoms mentioned above the only criteria for diagnosis? Not quite. In addition, a child must be symptomatic for at least 6 months, and the symptoms must interfere with the child's ability to function in at least two areas of life:
But who sets the standards for acceptable behavior in these settings?
If we ask a kindergartner to sit still for 20 minutes, or to pay attention to what he regards as a boring lecture, he might have trouble. But is this because he's got a psychological disorder, or because we're asking him to conform to standards of maturity that are unrealistically high?
The first look at a troubling pattern
Todd Elder of Michigan State University wanted to know if kids are being misdiagnosed with ADHD because they show normal levels of distraction and hyperactivity for their age.
So he trawled through some old data: a large, longitudinal study of kindergartners conducted by the U.S. National Center for Education Statistics (Elder 2010). And he took a look at two groups of kindergartners:
Elder's reasoning went like this: If kindergartners are getting diagnosed with ADHD because they have a real psychological disorder—and not because they show developmentally-normal signs of immaturity—then there should be no correlation between a child’s age and her diagnosis.
In other words, the youngest kindergartners should be no more likely than the oldest kindergartners to get diagnosed with ADHD.
But that's not what he found. On the contrary, the youngest kindergartners were 60% more likely to be diagnosed with ADHD than were the oldest kindergartners.
And being labeled with ADHD seemed to have lasting consequences. When Elder examined older kids, he found that the youngest students in the fifth and eighth grades were twice as likely to be medicated for ADHD.
Based on his analysis, Elder estimates that as many as 20% of the 4.5 million American kids identified with ADHD have been misdiagnosed (Elder 2010).
International studies report a similar trend
Elder's results have been replicated by researchers in other
For instance, in Taiwan, investigators found that boys and girls born in August (the last month before the official school cutoff) had 63% higher odds of being diagnosed than kids born in September. Their odds of being medicated were 76% higher (Chen et al 2016). And in Sweden, six-year-old kids born in the two month interval before the cutoff had 80% higher odds of being prescribed ADHD medication compared with kids born in the two month interval after (Halldner et al 2014).
The relative age effect has also been documented in Canada (Morrow et al 2012) and Israel (Hoshen et al 2016).
So are children the problem, or are school practices the problem?
For many children, the answer seems clear. They are perceived to have a disorder because they can't meet school standards, and the standards are unrealistic.
This school-centered interpretation is bolstered by an observation from the Swedish study: The youngest kids in the classroom didn't seem to have more trouble at home. Parental reports of ADHD-like symptoms were unrelated to a child's relative age.
Given that school pressures are contributing to misdiagnosis, what can we do about it? One approach is to delay school entry for kids who aren't ready. As the Swedish researchers note:
"...[F]lexibility regarding age at school start according to individual maturity could reduce developmentally inappropriate demands on children and improve the precision of ADHD diagnostic practice and pharmacological treatment."
This approach is common in Denmark, which may explain why researchers in that country have found almost no relative age effect on medication use Pottegård et al 2014).
But another alternative is to adjust our expectations about what kids can do. Can we redesign school in ways that acknowledge individual differences in maturity level? Or is would this be too costly and difficult to manage? These are important questions to research and debate.
It's true that ADHD is highly heritable.
We know this from twin studies that compare identical twins (who share nearly 100% of their genetic polymorphisms) with fraternal twins (who share, on average, only 50% of their genetic polymorphisms).
Identical twins are much more likely than fraternal twins to share a diagnosis of ADHD (Faraone and Mick 2010).
Presumably, that's because there are genes that play a role in the development of ADHD. These genes may code for traits that alter levels of neurotransmitters in the brain.
Researchers have developed medications that target specific
neurotransmitters, and some of these medications have high success rates in helping ADHD patients control their symptoms, at least in the short-term (Stuhec et al 2015).
But that doesn't mean that everybody diagnosed with ADHD has a disorder. And it doesn't mean that everybody benefits from medication.
The observation that kids with ADHD share certain genes—or even certain neurotransmitter profiles—is interesting but not unusual. We can say the same thing about kids who are shy, or perennially cheerful, or more aggressive than average (DiLalla 2002).
People are different, in part, because they carry different genes and develop different brain chemistries. That doesn't imply that all differences are pathological. Nor does it particularly matter why individual differences evolved—not when we're trying to decide if Marcus or Sylvia needs to be medicated.
Some researchers speculate that evolution has favored certain "ADHD genotypes." For instance, one theory posits that ancient social groups would have benefited by having a few ADHD-types as members. The more hyperactive, distractible people would have been the trailblazers—the people who sometimes discovered new survival tactics (Williams and Taylor 2006).
It's an interesting theory. But it doesn't—by itself—tell us if a child's behavior is pathological or worthy of medication.
Whether or not we regard ADHD as a "real" medical condition depends on other considerations, including our cultural assumptions. And even if we make the judgement that a child has a medical condition, we must weigh the costs of a treatment (like the risks of side-effects for taking a particular medication) against the apparent benefits.
For example, we might judge that a child has insomnia, but that diagnosis doesn't imply that medication is the best response. After examining the best available evidence, we may determine that the costs of medication (the problems and risks posed by side effects) outweigh any apparent benefits.
The same is true of an ADHD diagnosis. The most frequently prescribed drugs for ADHD have been linked with sleep problems, poor appetite, and abdominal pain (Storebo et al 2015; Punja et al 2016). For some people, such risks may make drug use undesirable.
Moreover, it's important to understand that these stimulants are classified as schedule II drugs by the FDA, indicating that they have a high potential for abuse and severe dependence. When abused or taken in high doses, the drugs may cause psychosis (Lakhan and Kirchgessner 2012).
Finally, we should be concerned about what we don't know. As the authors of leading meta-analyses have noted, virtually all of our knowledge of side effects is based on "very low quality evidence" (Storebo et al 2015; Punja et al 2016). Studies are poorly-controlled, and typically track children only for short intervals.
This conclusion about the state of research on ADHD-prescribed amphetamines summarizes the nature of the problem (Punja et al 2016):
"Most of the included studies were at high risk of bias and the overall quality of the evidence ranged from low to very low on most outcomes. Although amphetamines seem efficacious at reducing the core symptoms of ADHD in the short term, they were associated with a number of adverse events...Future trials should be longer in duration (i.e., more than 12 months), include more psychosocial outcomes (e.g. quality of life and parent stress), and be transparently reported."
Are some kids just overtired?
Young children aren't the only people who have trouble holding still and controlling their impulses.
Experimental studies show that elementary school kids become more moody when they get less sleep (El Sheikh and Buckhalt 2005). Even adults become more distracted and emotional when they are sleep-deprived (Yu et al 2007). Are some kids diagnosed with ADHD really just suffering from sleeplessness?
It's plausible. Studies confirm that ADHD-diagnosed kids are more likely to suffer from sleep
disorders (Shur-Fen Gau S 2006; Chiang et al 2010; Hansen et al 2013;
Moreau et al 2013). And in one study, kids who were treated for specific
sleep problems, like obstructive sleep apnea, experienced improvements in their ADHD symptoms (Huang et al 2007). Could your child's troubles stem from poor sleep? It's worth investigating.
Other conditions that can cause symptoms of ADHD in children include
possible that some cases of ADHD in children are really caused by poor working memory.
A child with low-capacity working memory has trouble keeping complex directions and goals in mind while she works. As a result, she may appear distracted or disobedient.
You may have heard the claim that ADHD doesn't exist. That it's a "lie" being perpetrated by special interests, like drug companies. Is this a valid point of view?
As with most claims, it depends on your specific meaning. It's not a lie that some people are more distracted, impulsive, or hyperactive than others. It's not a lie that some of these people suffer substantial impairments in their daily lives. And it's clear that attention deficits and hyperactivity -- like other traits -- are related to differences in brain chemistry.
So there's no question that millions of people fit the medical definition, and many of these folks have serious problems. What's less clear is causation. Do people diagnosed with ADHD represent a group affected by the same underlying causal mechanisms? Or is the population of ADHD patients a mixed bag? A collection of people who experience similar behavior problems for a variety of different reasons?
If your definition of ADHD depends on identifying a single, underlying cause, then there is reason to doubt the existence of ADHD. The science isn't there, at least not yet. But if you take a less restrictive definition, the label captures a real phenomenon: People struggling with behavioral tendencies that put them at a disadvantage in the current cultural environment.
For more reading on related topics related to ADHD in children, check out these research-based tips for helping children develop self-control and my articles about the psychological benefits of play and working memory in children.
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Content of "ADHD in children" last modified 8/17
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