Due to copyright issues, an electronic copy of the thesis must be ordered from the faculty. For the faculty to have time to process the order, the order must be received by the faculty at the latest 2 days before the public defence. Orders received later than 2 days before the defence will not be processed. After the public defence, please address any inquiries regarding the thesis to the candidate.
Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Professor Arnstein Mykletun, director of Centre for Population Health, Haukeland University Hospital
- Second opponent: Postdoctoral Researcher Camila Olarte Parra, Karolinska Institutet
- Third member and chair of the evaluation committee: Professor II Nils Eiel Steen, University of Oslo
Chair of the Defence
Professor Emeritus Erik Gunnar Jönsson, University of Oslo
Principal Supervisor
Researcher Guido Biele, Norwegian Institute of Public Health
Summary
Whether pharmacotherapy mitigates adverse academic outcomes remains one of the most pressing open questions in the field of ADHD research.
This thesis investigated the long-term effect of medication and special education services on academic achievement in Norwegian children diagnosed with ADHD. We used national registries for all individuals born in Norway in 2000–2007. These included prescription dispensations, national test scores, mental health diagnoses of children and relatives, and sociodemographic information. We employed causal inference methods for observational data, including the target trial emulation framework and sensitivity analyses.
On average, initiating medication had a small positive effect on grade eight national test scores approximately two years later. The results were compatible with effects corresponding to 4%– 21% of the achievement gap between children with and without an ADHD diagnosis.
However, via negative controls, the effect for the reading test was found to be biased by unmeasured common causes. We therefore extended a method of probabilistic bias analysis to examine the sensitivity of our conclusions to different plausible confounding scenarios. After bias adjustment, the estimated effect was slightly larger than the unadjusted estimate, but the substantive conclusion was unchanged.
Employing causal inference from observational data with sensitivity analysis, we found the effect of special education services to be near zero, and perhaps even negative for academic achievement. Possible explanations were discussed for the Norwegian context.
To investigate discrepancies between our results and the literature, we replicated the design of a Danish study in the Norwegian population. We also developed a new framework to evaluate the impact of study design choices. We partially replicated the larger effects reported in the Danish study and identified treatment operationalization as a main driver of the differences between the two studies’ original results.
This thesis adds to growing evidence suggesting that ADHD interventions have modest effects on academic outcomes.
Additional information
Contact the research support staff.