Conclusive Proof ADHD Is Overdiagnosed

School classroom with school desks and blackboard in Japanese high school
School classroom with school desks and blackboard in Japanese high school

There are 3 possible explanations for the  explosion of the ADHD diagnosis during the past 20 years -- with rates that have skyrocketed from only 3-5 percent of kids to 15 percent.

1) Diagnostic enthusiasts celebrate the jump as indication of increased awareness of ADHD and better case finding.

2) Diagnostic alarmists worry that we are making our kids sicker via environmental toxins, computers, an over-stimulating world, maternal drug use, or some combination.

3) Diagnostic skeptics attribute the change to the raters, not the rated -- it's not that the kids are sicker, it's rather that the diagnosis is being made too loosely.

There is no gold standard or biological test to prove precisely which view is correct and what would be the ideal rate of ADHD to best balance the risks and benefits of being diagnosed. I am strongly in the skeptic school. Long experience has taught me how great is the impact on diagnostic rates of even small changes in how any disorder is defined or appraised. And this is greatly amplified when heavy drug company disease mongering aggressively sells the disorder to doctors, parents, and teachers.

Fortunately, there is one ingenious and compelling indirect way to determine whether rates of ADHD are inflated. Five large studies in four different countries have compared rates of reported ADHD in the youngest vs the oldest kids in classrooms. The studies converge on the inescapable finding that we are turning immaturity into disease.

I invited Joan Lipuscek, MS LMFTA, a child and teen therapist, to summarize the results of these studies.


Taiwan Study (2016)

The sample was 378,881 Taiwanese school children, ages 4-17, who were in school from 1997 to 2011. Kids born just one month prior to the grade cutoff date were 61% more likely to be diagnosed with ADHD compared to their oldest classmates. These youngest children were also 75% more likely to be medicated. According to the authors, these findings "emphasize the importance of considering the age of a child within a grade when diagnosing ADHD and prescribing medication for treating ADHD."

Canada Study (2012)

The sample was 937,943 children in British Columbia ranging between 6 and 12 years of age and used data from between 1997 through 2008. The study found that male children born one month prior to the grade cutoff date were 30% more likely to be diagnosed with ADHD and 41% more likely to be medicated compared to the oldest male children in the same grade. Female children born one month prior to the grade cutoff date were 69% more likely to be diagnosed with ADHD and 73% more likely to be medicated compared to the oldest female children in the same grade. The study concluded that, "The potential harms of over-diagnosis and over-prescribing and the lack of an objective test for ADHD strongly suggest caution be taken in assessing children for this disorder and providing treatment."
 
Iceland Study (2012) 

The sample was 11,785 Icelandic children, ages 9 and 12. Male children born 1-4 months prior to the grade cutoff date were 52% more likely to be medicated for ADHD compared to the oldest male children in the same grade. Female children born 1-4 months prior to the grade cutoff date were 73% more likely to be medicated for ADHD compared to the oldest female children in the same grade. The study concludes that, "Relative age among classmates affects children's...risk of being prescribed stimulants for ADHD."

USA (2010)

Of all the studies reviewed, this one showed the highest increase in risk of diagnosis and medication of ADHD for the youngest children in a class. The study gathered data from 11,784 children in the Early Childhood Longitudinal Study-Kindergarten longitudinal survey tracked them for 9 years starting in 1998. Children born 1 month prior to the September 1st class grade cutoff date were 122% more likely to be diagnosed with ADHD and 137% more likely to be medicated for ADHD.  The study concludes by noting that, "Whether relatively young children are over-diagnosed, relatively old children are under-diagnosed, or both, current efforts to define and diagnose ADHD evidently fall short of an objective standard."

USA (2010)

This study used a sample of 35,343, children from the National Health Interview Survey and 18,559 children from the Medical Expenditures Panel Survey. Children born 1-3 months prior to the grade cutoff date were found to be 27% more likely to be diagnosed for ADHD and 24% more likely to be medicated for ADHD compared to children born 10-12 months prior to the grade cutoff data. The study does a nice job of relating its findings to the "real world" scale of the problem when it states, "To put our estimates into perspective, an excess of 2 percentage points implies that approximately 1.1 million children received an inappropriate diagnosis and over 800,000 received stimulant medication due only to relative maturity." 

For additional data on these studies see here.

Thanks so much, Joan. The results could not possibly be more consistent or convincing. Being the youngest kid in the class clearly puts you at great risk to be tagged with an inappropriate ADHD diagnosis and to be inappropriately treated with stimulant medication that is both unneeded and potentially harmful. We should let kids outgrow immaturity the old fashioned way by getting older, not treat it with a pill.

If you are concerned about the overdiagnosis and overtreatment of ADHD, you will also be interested in several recent blogs done with Keith Conners, the world's expert on the diagnosis.
On his regrets about how the diagnosis is misused
How parents can protect kids from overtreatment.
On the risks of diagnosing ADHD in adults.

Allen Frances is a professor emeritus at Duke University and was the chairman of the DSM-IV task force.