New study estimates US prevalence of ADHD is 3.5% and confirms strong association with co-occurring conditions

A study(opens in new tab/window) in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP), published by Elsevier, reports that the estimated true prevalence of ADHD in the US population is approximately 3.5% – substantially  lower than many publicized estimates. The study also found that over half of children with ADHD had a co-occurring mental disorder.

This is the first nationwide study of prevalence of Attention-Deficit/Hyperactivity Disorder (ADHD) to incorporate multiple informants. Many reports have highlighted national survey-based estimates of 8-10%, whereas scientific studies that use sophisticated modeling to estimate strictly defined ADHD support the 3-4% range reported here. These variations in prevalence estimates are due to differences in how ADHD is defined. Relying on strict definitions is necessary to detect genetic and other developmental alterations, although children identified with less strict criteria may genuinely require care for a related condition. This suggests the importance of careful definition and accurate diagnostic formulation to effectively study the scientific causes of ADHD.

In the study, researchers at Oregon Health & Science University (OHSU) Center for ADHD Research and from the University of Minnesota Masonic Institute for the Developing Brain were able to establish a definition of ADHD using both categorical and dimensional perspectives by leveraging the Adolescent Brain Cognitive Development Study (ABCD) dataset – a groundbreaking study of nearly 12,000 children aged 9-10 years old, funded by the National Institutes of Health to map behavioral, social and brain development over a 10 year period. The dataset provided the opportunity to use a nationwide sample to estimate prevalence of ADHD and correlations with clinical, neurocognitive and genetic measures.

The authors used four tiers to phenotypically define ADHD, with Tier 1 being the least strict and Tier 4 the strictest. Tier One relies on a single informant’s reported outcomes, while Tier Four relies on multiple informants on multiple measures. The study found that when using Tier Four definition criteria with the ABCD dataset, ADHD prevalence is estimated to be 3.53%, of which two-thirds were male. Additionally, those individuals identified as having ADHD with Tier 4 definition showed higher genetic risk; the authors computed a genetic risk score, a measure of heritability for certain disorders, and found that the likelihood of ADHD was 60% higher for those with high genetic risk scores than for those with average or lower scores.

Researchers also confirmed that ADHD often presents with other psychiatric symptoms and conditions. Again, when using the stricter definition, ADHD was strongly correlated with irritability, disruptive behavior and difficulty with concentration and executive functioning. Additionally, a substantial proportion of those individuals identified as having ADHD also had co-occurring conditions such as an anxiety, mood or behavior disorder.

“This research is significant because it underscores the need for neurobiological research using a sophisticated, multi-method way of defining ADHD, which is something that was unclear before. It also demonstrates that many children presenting with what appears to be ADHD, while really in need of care, may not have a neurobiologically characterized ADHD syndrome,” said Joel Nigg, Ph.D., Director for the Center for ADHD Research at OHSU, who led the study. “This opens the door to ask why, and to consider multiple kinds of ADHD. Our hope at our center is that an expanded understanding of ADHD will sharpen the effectiveness of our science and ultimately accelerate progress on causes and treatments.”

While the study provided key epidemiological and clinical data, it was not able to effectively address questions about the potential variation in ADHD prevalence and characteristics among racial and ethnic groups, which Nigg and his team say should be a priority in future research efforts. The children in this study are being followed by a national consortium over a 10 year period, providing rich opportunity to track long term change and stability in ADHD, something the team will be undertaking along with other research groups around the country.

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Notes for editors

The article is "Attention-Deficit/Hyperactivity Disorder: Restricted Phenotypes Prevalence, Comorbidity, and Polygenic Risk Sensitivity in the ABCD Baseline Cohort” Michaela M. Cordova, BA, Dylan M. Antovich, PhD, Peter Ryabinin, MS, Christopher Neighbor, MS, Michael A. Mooney, PhD, Nathan F. Dieckmann, PhD, Oscar Miranda-Dominguez, PhD, Bonnie J. Nagel, PhD, Damien A. Fair, PhD, Joel T. Nigg, PhD https://doi.org/10.1016/j.jaac.2022.03.030(opens in new tab/window). It currently appears on the JAACAPArticles In Press(opens in new tab/window) page and will appear in the Journal of the American Academy of Child and Adolescent Psychiatry, volume 61, issue 10 (October 2022), published by Elsevier(opens in new tab/window).

Copies of this paper are available to credentialed journalists upon request; please contact the JAACAP Editorial Office at [email protected](opens in new tab/window) or +1 202 587 9674. Journalists wishing to interview the authors may contact Nicole Rideout, Senior Media Relations Specialist; e-mail: [email protected](opens in new tab/window)

About JAACAP

Journal of the American Academy of Child and Adolescent Psychiatry(opens in new tab/window) (JAACAP) is the official publication of the American Academy of Child and Adolescent Psychiatry. JAACAP is the leading journal focusing exclusively on today's psychiatric research and treatment of the child and adolescent. Published twelve times per year, each issue is committed to its mission of advancing the science of pediatric mental health and promoting the care of youth and their families.

The Journal's purpose is to advance research, clinical practice, and theory in child and adolescent psychiatry. It is interested in manuscripts from diverse viewpoints, including genetic, epidemiological, neurobiological, cognitive, behavioral, psychodynamic, social, cultural, and economic. Studies of diagnostic reliability and validity, psychotherapeutic and psychopharmacological treatment efficacy, and mental health services effectiveness are encouraged. The Journal also seeks to promote the well-being of children and families by publishing scholarly papers on such subjects as health policy, legislation, advocacy, culture and society, and service provision as they pertain to the mental health of children and families.

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