Study data published in the Journal of the American Academy of Child & Adolescent Psychiatry provide prevalence estimates for attention-deficit/hyperactivity disorder (ADHD) and comorbid medical conditions. Per data from a large, population-based cohort study, the national prevalence of ADHD was estimated at 3.5%. Comorbidity rates were high, with up to 70% of the affected sample reporting at least 1 medical condition in addition to ADHD.  

Investigators extracted data from the Adolescent Behavior Cognition Development (ABCD) study, a longitudinal cohort study that enrolled children aged 9 to 10 years at baseline from 21 sites around the US. The cohort study captured participants’ mental health status using the parent-completed Kiddie Schedule of Affective Disorders and Schizophrenia (KSADS-COMP). Results from the parent-reported Childhood Behavioral Checklist and teacher-reported Brief Problem Monitor were also integrated.

ADHD prevalence and comorbidity were calculated for 4 tiers of ADHD severity, with tier 4 requiring convergence of the KSADS-COMP and parent and teacher ratings. Genotyping data were also extracted and polygenic risk scores (PRS) were calculated for patients in each of the 4 ADHD phenotypes.


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The ABCD cohort comprised 11,878 children. The estimated prevalence of current ADHD in children aged 9 to 10 years was 3.53% (95% CI, 3.14-3.92) when the most stringent ADHD tier was applied. Of these ADHD cases, 70% had a comorbid psychiatric disorder, including 30.9% (95% CI, 25.7-36.7) with a comorbid disruptive behavior disorder, 27.4% (95% CI, 22.3-33.1%), with an anxiety or fear disorder, and 2.1% (95% CI, 1.2-3.8%) with a mood disorder.

Children in the top decile of PRS risk had a 63% increased chance of having ADHD compared with the bottom half of the polygenic load (P <.01). However, this association was only present within the most stringent ADHD phenotype (tier 4) and not in tiers with less strict diagnostic criteria.

This study provides robust estimates of the prevalence and comorbidities of ADHD in children. Study limitations include the high degree of missingness for certain measures, though multiple imputation was used to correct for this.

“The analysis here suggests that the most dependable findings for clinical application will benefit from utilization of a refined categorical phenotype for ADHD cases,” the investigators noted.

Reference

Cordova MM, Antovich DM, Ryabinin P, et al. Attention-deficit/hyperactivity disorder: restricted phenotypes prevalence, comorbidity, and polygenic risk sensitivity in ABCD baseline cohort. J Am Acad Child Adolesc Psychiatry. Published online April 11, 2022. doi:10.1016/j.jaac.2022.03.030