ADHD prevalence in US nears 1 in 10

Telephone surveys of parents in the US about the health and well-being of 73,123 children and youths between 4 and 17 years of age revealed that at one time or another 9.5% of the parents said “a doctor or other health-care provider had … told [the parent] that [the] child had ‘attention deficit disorder or attention deficit hyperactive disorder, that is, ADD or ADHD.'” This represents a substantial increase from the 7.8% of parents who responded in the same way to a similar question four years earlier.

I don’t have time to dive into the details of the study right now, but interested readers can chase it through the US Centers for Disease Control. It was published several days ago as “Increasing Prevalence of Parent-Reported Attention-Deficit/Hyperactivity Disorder Among Children — United States, 2003 and 2007” in the Morbidity and Mortality Weekly Report (MMWR).

2 Responses to “ADHD prevalence in US nears 1 in 10”

  • Did you see the article by Daniel Carlot on this study? Here’s the link:

    Here are more than a few paragraphs:

    Here’s the problem: The science behind the numbers is suspect, if not outright bogus.

    Here’s how they came up with the ADHD diagnoses. First, they hired a bunch of interviewers — none of whom were doctors (nor did they have any other clinical training, apparently) — to place phone calls to a random sampling of households. Then, the interviewers asked parents about dozens of health issues, plowing though a 114-page computerized questionnaire. Buried in the middle of the questionnaire were these three questions about ADHD:

    “Does your son currently have ADD or ADHD?”

    “Would you describe his ADD or ADHD as mild, moderate or severe?”

    “Is he currently taking medication for ADD or ADHD?”

    To sum up, interviewers with no medical background determined that 5.4 million U.S. children have ADHD by asking their parents three questions over the phone.

    Nobody actually met with the children or the parents. Nobody explained each of the diagnostic criteria for ADHD. And unlike legitimate epidemiological studies, no clinicians were sent to a sub-sample of the respondents to test the validity of the phone interviews.

    If I had a child with problems, I certainly would not feel particularly confident with this diagnostic process.

    ADHD is a very tricky diagnosis. Lots of kids have trouble in school and at home. But only a small percentage of them have ADHD.

    Let’s assume you’re worried about your son. If you really want to know if he has ADHD, you’d have to bring him to a pediatrician or a mental health clinician. The doctor would interview you and your son, call the school to find out what the teachers think, and would then put all the data together in order to come up with a diagnosis. It might, indeed, turn out that your son had ADHD. On the other hand, he could have a learning disability. Or maybe he can’t concentrate because he’s getting bullied at school. Or perhaps there’s a messy divorce going on in the home and your son can’t think about schoolwork because he’s wondering why mom and dad are yelling at one another all the time. The non-ADHD possibilities are endless.

    There’s no conspiracy going on here. The CDC was not claiming to actually be able to make complex diagnoses over the phone. They were merely trying to determine if parents believed a doctor had made such a diagnosis. Unfortunately, people’s memories are often flawed, and the validity of a past “diagnosis” of ADHD is always questionable. When a patient tells me that he or she was diagnosed with ADHD once, careful questioning usually reveals that the diagnosis was made casually, and is rarely valid.

    The CDC conducted this study as a sincere attempt to track the prevalence of a number of childhood illnesses, using the resources and tools at their disposal. For less subjective illnesses, like diabetes or epilepsy, the phone call technique might be more accurate, but still questionable. But for ADHD, it inevitably leads to over-diagnosis — on a vast scale.

  • Liz, thanks for the comment and for pointing me to Professor Carlot’s critique of the CDC study. He made some important points about the study, though I’d say they are a bit hyperbolic.

    Professor Carlot’s observation that there the study does not represent a conspiracy seems sensible to me. It’s just a telephone survey—nothing more, nothing less. Reasonable people won’t take it as the equivalent of assessing a well-selected sample using many highly trained, multi-disciplinary teams of clinicians who employ the most robust, reliable, and valid instruments under the standardized conditions. Nor will they take it as equivalent to an estimate based on the number of prescriptions that pediatricians write for patients between 4 and 17 years of age in the US. Nor will they take it as the equivalent to an estimate based on a survey of randomly selected primary-grade teachers who complete a Connors checklist of all the students in their classrooms whose last names begin with the letters A, K, M, or T. Each of these yields different views of the elephant.

    Furthermore, as I pointed out when I commented on the previous version (see on “CDC on ADHD” over on EBD Blog) there are many possible reasons for a telephone survey of parents to have error (in the technical sense, i.e., variation).

    To be sure, the data in a survey such as this can not be taken as showing what one might call the true prevalence of a condition, whether it is ADHD, Autism, diabetes, blondness, or just about anything else. Not only might reporters (parents in this case) give mistaken information for any of many different reasons (faulty memories, perceptions of what the interviewer hopes to hear, and so forth), but also the reporter might accurately report false information provided to her or him in the past (a person selling herbs might have suggested some remedy for ADHD or, after a brief, one-time encounter with the child, a dentist might have made a comment about ADHD). So, readers of the CDC report should take it for what it is: Just a report of a telephone survey showing what parents report.

    So, in the vaster scale of things, these findings are not particularly momentous. I agree with Professor Carlot that they’re likely to be overplayed by popular media. Of course, what isn’t? We can hear the newscasters’ tease at the top of the hour: “In the headlines tonight: President Smith has yet another white hair, ADHD has skyrocketed to 10% in a new government survey, three countries have attacked each other with nuclear weapons, and shocking new photos of Priscilla P. Princess, star of stage, screen, and billboard reveal an untreated pimple. We’ll have all this and more right after these words.”

    (By the way, Liz, when I looked at what I’d written in 2005 about the previous version of the CDC study, I found a typo…bummer. I had to fix it. Thanks for making me go back to it.)

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