Younger children in the same grade with peers that may be almost 1 year
older are significantly more likely to be diagnosed with
attention-deficit/hyperactivity disorder. This may lead to overdiagnosis and
overprescribing of medications among these children, according to researchers.
Richard L. Morrow, MA, and colleagues from the University of British
Columbia examined a cohort of 937,943 children in British Columbia, where the
cut-off for entry into kindergarten or grade one is Dec. 31. Children were
included in the 11-year study at some point between the ages of 6 and 12 years.
Researchers compared children who were nearly 1 year apart in age (those
born in December and those born in January nearly 1 year earlier). When divided
between boys and girls, the younger boys were 30% more likely to have a
diagnosis of ADHD, and the younger girls were 70% more likely to have a
diagnosis of ADHD. Similarly, the younger boys were 41% more likely, and girls
77% more likely, to have a prescription for a medication to treat ADHD,
compared with their older peers.
The relative age of the children is influencing whether they are
diagnosed and treated for ADHD, Morrow said in a press release. Our
study suggests younger, less mature children are inappropriately being labeled
and treated. It is important not to expose children to potential harms from
unnecessary diagnosis and use of medications.
Disclosure: Drs. Morrow, Garland, Wright, Maclure and Dormuth
received a Catalyst grant from the Canadian Institutes of Health Research to
study postmarket drug safety and effectiveness. Dr. Maclure is employed by the
University of British Columbia and the British Columbia Ministry of Health. Dr.
Taylor is employed by the British Columbia Ministry of Health. No other
competing interests were declared.