TOPLINE

Medication for attention-deficit/hyperactivity disorder (ADHD) had no statistically significant evidence of a causal effect on grade point average or individual school subject grades among Norwegian children and adolescents on the margin of treatment, who were followed up for a maximum of 10 years, a registry-based analysis found.

METHODOLOGY

• In a registry-based population study, researchers analysed individual-level data of 6255 Norwegian children aged 5-15 years diagnosed with ADHD between 2009 and 2011 who were followed up through the completion of 10th grade (at 15-16 years of age).
• Treatment exposure was defined as the cumulative number of defined daily doses of ADHD medication filled from diagnosis through the end of 10th grade; 74%-88% of patients filled prescriptions, depending on the diagnostic age group and treatment period.
• Outcomes were final grades in the nine subjects mandatory in 10th grade, the grade point average across those subjects, and two binary outcomes: exemption from at least one subject and no basis for assessment in at least one subject.
• The researchers compared ordinary least squares (OLS) regression with an instrumental variable model. The instrumental variable estimates applied to patients on the margin of treatment, whose medication use depended on their clinic's prescribing preference.
• Models were adjusted for patient and family characteristics (such as sex and parental education) and features of each clinic's catchment area, including the high school dropout rate.

TAKEAWAY

• In the OLS analysis, treatment (scaled so that 1 represented full-time treatment) was linked to a 0.05-point higher grade point average (95% CI, 0.02-0.09; SD, 0.94), a small effect of roughly 5% of the SD.
• In the instrumental variable model, treatment had no statistically significant effect on grade point average (coefficient, -0.01; Anderson-Rubin 95% CI, -1.13 to 0.15; about 0.01 SD), although the authors noted that the estimates were imprecise.
• In the instrumental variable model, no individual school subject showed a statistically significant treatment effect; in the OLS analysis, the strongest association was observed for maths (coefficient, 0.13; 95% CI, 0.09-0.17; SD, 1.07).
• In the OLS analysis, neither exemption nor no basis for assessment was significantly associated with treatment (risk differences, 0.01 [95% CI, -0.01 to 0.03] and -0.01 [95% CI, -0.02 to 0.00], respectively), and instrumental variable estimates were also non-significant.

IN PRACTICE

"Although our results do not provide evidence of any positive causal effects of pharmacological treatment on academic outcomes, neither do they suggest negative effects," the authors wrote.

"Nonetheless, the potential improvement of grades is not the only reason to consider pharmacological treatment for ADHD," they added.

SOURCE

The study was led by Ingvild Lyhmann, Haukeland University Hospital, Bergen, Norway. It was published online on September 28, 2026, in The British Journal of Psychiatry.

LIMITATIONS

The study was limited by imprecise results from its main analysis, with wide CIs. The instrument, clinic prescribing preference, was weaker than conventionally required for standard inference and too weak to analyse female individuals separately or to interpret age-stratified models. Treatment was averaged over time, routine care likely involved less consistent medication use and monitoring than a trial, non-drug treatments were not captured, and the findings were not applicable beyond patients on the margin of treatment.

DISCLOSURES

The study was funded by the Research Council of Norway. One author also received funding from the Western Norway Regional Health Authority, and the research group was additionally supported by the Centre for Research and Education in Forensic Psychiatry, Haukeland University Hospital. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.