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Younger age at school entry increases risk for ADHD diagnosis
Entering school at an earlier age increased the risk for attention-deficit/hyperactivity disorder diagnosis and medication treatment among a cohort of children in Asia, according to recent research in The Journal of Pediatrics.
“This study investigated whether the impact of relative age is exclusive to Western countries, such as the United States, Canada, Spain and Sweden, or is also present in Asian countries, such as Taiwan,” Mu-Hong Chen, MD, of the department of psychiatry at Taipei Veterans General Hospital, and colleagues wrote. “Our results supported the study hypothesis, which is consistent with previous studies conducted in the U.S. and Canada, and indicated a significant effect of relative age on ADHD diagnosis and treatment.”
The researchers studied data from the Taiwan National Health Insurance Research Database for 378,881 children aged 4 to 17 years, from Sept. 1 1997 to Aug. 31, 2011. Chen and colleagues used a cut-off birthdate of Aug. 31 for school enrollment to identify children entering school at a younger age. Statistical analysis was used to determine the risk for diagnosis and treatment for younger children born in August vs. those who were older and born in September.
Study data indicated that boys (OR = 1.63; 95% CI, 1.45-1.84) and girls (OR = 1.71; 95% CI, 1.36-2.15) who entered school at a younger age had a greater risk for being diagnosed with ADHD and being treated with ADHD medications (boys; OR = 1.76; 95% CI, 1.53-2.02; girls; OR = 1.65; 95% CI, 1.26-2.18) compared with older children.
According to the researchers, this trend was not observed when adolescents born in August were compared with adolescents born in September (OR = 1.27; 95% CI, 0.98-1.64), suggesting that increased age and maturity may decrease the risks for ADHD diagnosis associated with birth month.
“The relative age among classmates affects the academic performance of children and their risk of receiving ADHD diagnosis and medication,” Chen and colleagues wrote. “Our findings emphasize the importance of considering the age of a child within a grade when diagnosing ADHD and prescribing medication to treat ADHD.” – by David Costill
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Chen and colleagues utilized a very large sample of youth (n = 378,881) across a wide age-range (4 to 17 years) to examine the role of relative age on the likelihood of receiving a diagnosis of ADHD in Taiwan. While this topic has been heavily investigated in Westernized countries (ie, United States, United Kingdom, Canada, Spain and Sweden), this is the first such study to examine the role of relative age on ADHD diagnosis in an Asian sample. Results suggest that both boys and girls who were relatively younger than peers within their grade (ie, those who were born in August compared with those who were born in September) were 1.63 to 1.71 times more likely to receive a diagnosis and 1.65 to 1.76 times more likely to be prescribed medication for ADHD.
I find the fact that the prevalence of ADHD increased steadily across the relative age groups particularly compelling. That is, the rate steadily increases from approximately 2.8 to 4.5 across the month-by-month age increases. Furthermore, the authors attended to the actual age of the children and adolescents in the sample, noting that the relative age effect was much stronger among younger children (ie, pre- and elementary school-aged rather than among teens), suggesting that younger children may “catch up” with their older peers by the teen years. The real “take-home” message here is that there may be an over-identification of relatively younger children within a particular grade who may not actually have a diagnosis, and perhaps, a relative under-identification of relatively older children with ADHD who are not receiving the help they need. Obviously, it is important to provide all children (regardless of diagnosis) with the help that they need to succeed; however, this study has important implications related to both future research and practice, as future studies can utilize this information when attempting to identify causes and correlates of the disorder, and practitioners can utilize this information when deciding on a diagnosis and/or engaging in treatment planning.
