Child Psychiatry Consult

ADHD boundaries with normal behavior


Case summary

Dylan is a bright and lively 10-year-old boy who has always been energetic and passionate. His parents have celebrated his exuberance but now have become concerned that there is "something more," after his teacher has needed to remove him from class for several episodes of impulsive and disruptive behavior. Further history reveals that, compared with his classmates, he can be quite distractible and often needs a lot of prompting and redirection to complete his work. Dylan is an intelligent child who has always managed to do well in school despite some longstanding challenges with attention. His performance has slipped somewhat as the academic load increases, although not to the point that he is in jeopardy of being held back.

Dr. David C. Rettew

At home, Dylan enjoys playing outside but also is drawn to video games, an activity that seems to hold his attention well. His parents get frustrated with needing to repeat requests several times and having to remind him to be quieter in the house.


Attention-deficit/hyperactivity disorder, like all other psychiatric disorders, is defined in binary terms as being present or not-present. Nonetheless, it has become abundantly clear from research studies that the symptoms exist dimensionally and are normally distributed in a manner such as height. As such, diagnosing ADHD is analogous to diagnosing someone as being tall. Given this reality, how does a clinician figure out when a child really "has" a disorder, versus the behavior being "just" part of normal behavior?

All of the diagnostic criteria for ADHD include behaviors that at age-appropriate levels are considered completely normal. To qualify as a symptom that is present, the behaviors have to occur "often" and be inappropriate to the child’s developmental level. These subjective judgments about moving targets make drawing the line difficult for clinicians. Most children are well within normal limits and others are clearly beyond them, yet that leaves a sizable group somewhere in that middle "gray zone."

Making matters more complicated is the increasing but still insufficient evidence suggesting that this dimensionality exists when it comes to the underlying neurobiology of ADHD as well. In other words, the genes, environmental factors, brain regions, neurotransmitters, etc., that determine why a child has an average attention span or activity level are the same ones involved in ADHD. Such a revelation, however, in no way should be interpreted as ADHD being not "real," any more than other dimensional nonpsychiatric conditions (hypertension, hyperlipidemia).

This continuum of behaviors, however, does present a real diagnostic challenge. The inconvenient reality is that there really may not be any "true" rate of ADHD at 5%, 7%, or more recently, 11%. Many people make much of assessing whether or not there is associated impairment with the behaviors, but the truth of the matter is that impairment itself is dimensional.

Thus, we need to appreciate the complexities and limitations of this challenging diagnosis without throwing up our hands in frustration and giving up. After all, these problems can get significantly better with treatment. Here are a few tips to consider.

1. In making an ADHD diagnosis, use quantitative rating scales that appreciate this dimensional nature. Ideally, these instruments should be standardized by age and sex so that, for example, scores of 8-year-old boys can be compared to those of other 8-year-old boys. Don’t feel compelled to come up with a diagnosis on the spot if this procedure takes a little time in getting input from multiple people (parents, teachers, self-report).

2. Don’t stop investigating just because you arrive at an ADHD diagnosis. There are many factors that can result in a child struggling with these behaviors. Poor sleep, excessive screen time, inadequate nutrition, suboptimal parenting practices, exposures to lead and other substances, and lack of exercise are some factors that can underlie these problems. Correcting them can often make a big difference and in some cases can obviate the need for medication.

3. Approach a dimensional diagnosis with dimensional treatment. Just as many patients with borderline levels of hypertension or borderline glucose levels might be recommended to try nonpharmacological interventions first, the same principle can be applied to ADHD. Parent behavioral management, skills training, and addressing potential causes or exacerbating causes described in No. 2 can all provide important benefits.

The bottom line here, in my view, is to appreciate and respect the inherent blurriness of these boundaries without it leading to clinical paralysis. Children who struggle with inattention and hyperactivity are well known to be at risk for a variety of negative outcomes. Pediatricians have a large number of options to help these children that have been shown to be effective and can be individually tailored to each specific case.

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