Inside the New Data on ADHD Diagnosis Rates

The New York Times had a cover story recently reporting on the estimated prevalence of Attention-Deficit/Hyperactivity Disorder from the 2011-2012 National Survey of Children’s Health (they don’t identify the survey by name).

The story is going to get a lot of people interested in what is happening to children — every new datapoint on ADHD is noteworthy because it allows journalists to reopen the black box on childhood behavioral health disorders, and to raise the perennial alarm bells about over-diagnosis of children.

All of the issues raised in the article are valid. Many children with very mild impairments are getting a diagnosis, and enterprising drug companies are increasing demand for their product by implying that ADHD medications are a cure for generalized social impairments.

But — and this is critical – we have little systematic population-level data to compare the reported prevalence of a diagnosis with underlying data on ADHD symptoms in children. The NSCH, for example, does not include a validated set of questions measuring ADHD symptoms (like the Strengths and Difficulties questionnaire). This is a major shortcoming, because it leaves us to speculate about how much the diagnosis data reflect real underlying changes in symptoms in children, versus more prescription-pad-happy diagnosis from doctors and therapists.

For example, the article quotes William Graf at Yale: “Mild symptoms are being diagnosed so readily, which goes well beyond the disorder and beyond the zone of ambiguity to pure enhancement of children who are otherwise healthy.”

Dr. Graf is undoubtedly right, but nobody can say with certainty how much the diagnosis patterns may also be driven by alarming changes in the profile of environmental toxicants, exposure to over-stimulating television for toddlers, or disruptive family environments (since 2007, we also went through four years of major economic turmoil, which is disruptive to children and their parents). Again, this is speculative, but we need to get better answers to these and other potential exposures.

Second, and also critical, the NSCH numbers reported in the NYT focus on lifetime diagnosis rather than current diagnosis. This is a less accurate way to measure changes across successive cohorts, because it tangles up two factors — how doctors are diagnosing now, and how they diagnosed at earlier periods in time. Perhaps not surprisingly, the largest growth in lifetime ADHD diagnosis occurred among high school aged, not preschool-aged, youth. High school kids today may be carrying around a diagnosis that was given to them when they were 8 or 10 years old, but may no longer have symptoms of ADHD.

Third, although the lifetime diagnosis rates are growing, the rate of growth is slowing. Check out the CDC report from the 2003 and 2007 data. The diagnosis grew about 21.8% between those two survey waves compared to the 16% reported between 2007 and 2011. Again, these are concerning numbers, but I would have expected the lifetime diagnosis rate to have grown even if the current diagnosis rate did not increase, because kids diagnosed during the peak period (elementary school) are still carrying their old diagnoses in high school age.

We need to work much more with these data to understand what is happening, but let’s drop the panic level for a moment while we do. We still don’t know whether the ADHD epidemic is still peaking or has begun to steady out, and we also don’t have a great handle on what biological and social exposures may be driving ADHD symptoms over time (and whether these exposures are rising or falling).

Brendan Saloner is a postdoctoral fellow at the University of Pennsylvania in the Robert Wood Johnson Health and Society Scholars Program and founding co-editor of the blog, Inequalities, where this post first appeared.