A Population-Based Study of Stimulant Drug Treatment of ADHD and Academic Progress in Children
Zoega H et al. – Later start of stimulant drug treatment of attention–deficit/hyperactivity disorder is associated with academic decline in mathematics. Methods
- The linked nationwide data from the Icelandic Medicines Registry and the Database of National Scholastic Examinations.
- The study population comprised 11,872 children born in 1994–1996 who took standardized tests in both fourth and seventh grade.
- The authors estimated the probability of academic decline (drop of ≥5.0 percentile points) according to drug exposure and timing of treatment start between examinations.
- To limit confounding by indication, the authors concentrated on children who started treatment either early or later, but at some point between fourth–grade and seventh–grade standardized tests.
- In contrast with nonmedicated children, children starting stimulant treatment between their fourth– and seventh–grade tests were more likely to decline in test performance.
- The crude probability of academic decline was 72.9% in mathematics and 42.9% in language arts for children with a treatment start 25 to 36 months after the fourth–grade test.
- Compared with those starting treatment earlier (≤12 months after tests), the multivariable adjusted risk ratio (RR) for decline was 1.7 (95% confidence interval [CI]: 1.2–2.4) in mathematics and 1.1 (95% CI: 0.7–1.8) in language arts.
- The adjusted RR of mathematics decline with later treatment was higher among girls (RR, 2.7; 95% CI: 1.2–6.0) than boys (RR, 1.4; 95% CI: 0.9–2.0).