Objective: To describe trends in the prevalence of prescribed attention-deficit hyperactivity disorder (ADHD) medication by Canadian preschoolers and school-age children and to compare these with trends in the prevalence of the ADHD diagnosis between 1994 and 2007.
Methods: Subjects participated in the National Longitudinal Survey on Children and Youth, a Canadian prospective survey collecting data biennially. Three cross-sectional samples of nonreferred children, aged 3 to 9 years and representative of Canadian children for 1994-1995 (n = 12 595), 2000-2001 (n = 13 904), and 2006-2007 (n = 14 655), were selected for the analyses. Information on prescribed medications and ADHD diagnosis was reported by each child's parents. Prevalence was estimated at each cycle, taking the child's age and sex into account.
Results: The estimated prevalence of prescribed medications and ADHD diagnosis in Canada was generally low (less than 3%), but higher for boys (less than 4%) and school-age children (less than 5%). Preschoolers' prevalence of both prescribed medications and ADHD diagnosis stayed stable between 1994 and 2007 (1% or less), while that of school-age children increased nearly 2-fold. Boys' prevalence was higher than that of girls, but girls show the steepest increase over time, up to 2.1-fold. The association between prescribed medications and ADHD diagnosis has strengthened during the 2000s: a greater number of medications were used for children with ADHD (from 43% in 2000 to 59% in 2007) while off-label use of prescribed medications decreased among school-age children.
Conclusions: The upward trend in the prevalence of prescribed ADHD medications and ADHD diagnosis currently observed in contemporary societies is also occurring in Canada, except with preschoolers.