Attention-deficit hyperactivity disorder (ADHD) is most often identified in childhood and is characterized by difficulty sustaining attention, controlling activity levels, and regulating impulses. While the exact causes remain unclear, research suggests that a child’s relative age within a school grade may influence the likelihood of receiving an ADHD diagnosis and medication. A large Taiwanese study published in The Journal of Pediatrics investigated this possible link.
Researchers led by Dr. Mu-Hong Chen analyzed health records for 378,881 children aged 4 to 17 years between September 1, 1997 and August 31, 2011 using Taiwan’s National Health Insurance Research Database. Taiwan’s school-entry cutoff is August 31, which allowed the team to compare the youngest children in a classroom—those born in August—with the oldest—those born in September—and examine whether birth month was associated with higher rates of ADHD diagnosis and ADHD medication prescriptions.
The overall analysis showed that children born in August were more likely than those born in September to be diagnosed with ADHD and to receive ADHD medication. When the researchers stratified results by age, the increased risk was concentrated among preschool and elementary school-aged children born in August. By adolescence, the association was no longer evident, suggesting that as children mature the influence of being relatively younger within a grade diminishes.
Globally, both ADHD diagnoses and prescriptions for ADHD medications in children and adolescents have risen over recent years. The concept of relative age—how young or old a child is compared with classmates—can act as a proxy for neurocognitive maturity. Younger children in a given class may display behaviors that, relative to older peers, appear more inattentive or hyperactive, increasing the chance of an ADHD diagnosis or treatment. Dr. Chen emphasized the clinical relevance of these findings: clinicians and educators should consider a child’s age within the grade when evaluating behavior and making treatment decisions.
Source: Becky Lindeman, Elsevier Health Sciences
Image credit: The image is in the public domain.
Original research: Abstract for “Influence of Relative Age on Diagnosis and Treatment of Attention-Deficit Hyperactivity Disorder in Taiwanese Children” by Mu-Hong Chen et al., Journal of Pediatrics. Published online March 10, 2016. doi:10.1016/j.jpeds.2016.02.012
Abstract
Influence of Relative Age on Diagnosis and Treatment of Attention-Deficit Hyperactivity Disorder in Taiwanese Children
Objective
This study aimed to determine whether a child’s relative age within a school grade influences the likelihood of being diagnosed with ADHD and of receiving ADHD medication, with a specific focus on data from Taiwan.
Study design
The investigators included 378,881 children aged 4–17 years who were registered in the Taiwan National Health Insurance Research Database during the study period (September 1, 1997 to August 31, 2011). Using logistic regression, they compared the odds of receiving an ADHD diagnosis and of being prescribed ADHD medication for children born in August (the youngest in class) versus those born in September (the oldest in class).
Results
Children born in August had significantly higher odds of being diagnosed with ADHD and of receiving ADHD medication compared with children born in September. Specifically, boys born in August had an increased odds ratio (OR) of 1.63 (95% CI, 1.45–1.84) for ADHD diagnosis and OR 1.76 (95% CI, 1.53–2.02) for receiving medication. Girls born in August showed similar patterns with OR 1.71 (95% CI, 1.36–2.15) for diagnosis and OR 1.65 (95% CI, 1.26–2.18) for medication. Sensitivity analyses across different time periods produced consistent results.
Conclusions
Relative age—reflecting neurocognitive maturity compared with peers—appears to be an important factor in the risk of ADHD diagnosis and medication use among children. The elevated risk for the youngest children in a grade highlights the need for clinicians, parents, and educators to consider a child’s age relative to classmates when evaluating behaviors and deciding on diagnostic or pharmacologic treatment for ADHD.