Effects of pharmacological treatment and special education on school performance of children with ADHD

Children and adolescents with attention deficit hyperactivity disorder (ADHD) often have problems at school. These problems have a negative impact on the well being of these children and their families. In the long-term, problems at school lead to low educational attainment and unemployment and thus low well being also in adulthood. Despite the fact that problems at school are a core challenge for children with ADHD, there is to date little research on long-term effects of ADHD medication and special education, two interventions that in theory should improve school performances. Therefore, this project investigates long-term effects of ADHD medication and special education on the school performance. To estimate the effects of these interventions, the project uses data from Norwegian registries and the Norwegian mother, father and child cohort Study. This allows investigating if children with ADHD who received an intervention improve their school performance more than children with ADHD who did not receive it. The project will use statistical techniques to account for the fact that children with more problems are typically more likely to receive a treatment. The large sample size will also allow us to investigate if variables like parental education, additional mental health problems, or age at onset of treatment influence the effectiveness of interventions. The project will be implemented by and interdisciplinary group research with backgrounds in psychology, psychiatry, special education, and statistics and involves users throughout all project phases to insure the relevance of the research results. PROJECT PROGRESS: Until now the project implementation focused on administrative tasks. We successfully applied for approval from the Regional Committees for Medical and Health Research Ethics (South East), prepared a Data Protection Impact Assessment, and successfully applied for data from a number of registries (Population register, education register, birth register, patient register, drug prescription register) and are currently awaiting the data delivery. In addition, we have hired 2 PhD students, whose employment began 01.09.2021.

Attention-Deficit Hyperactivity Disorder (ADHD) is the neurodevelopmental disorder with the highest prevalence in childhood. Beyond symptoms of inattention, hyperactivity, and impulsiveness, it is linked to low educational attainment, low workforce participation, and low levels of well-being, making it a severe burden to individuals and society. Randomized controlled trials (RCTs) showed that ADHD medication reduces symptoms, but its long-term effects on school performance are unclear. Children in Norway with ADHD who have learning problems have also the right to individual special education (ISE). Again, RCTs document the effectiveness of specific interventions in organised experimental settings, but population-based observational studies could not show clear positive effects of ISE. The combined effects of medication and ISE remain unknown. Hence, identifying treatment approaches that improve school performance of ADHD patients is an important challenge. This project assess the long-term effects of medication and ISE on school performance, with emphasis on the effectiveness of treatment patterns resulting from variations in onset, duration, and intensity of treatment. We will link Norway’s national patient and prescription registries with results from standardised achievement tests and a large prospective cohort study in order to estimate separate and combined effects of medication and ISE. To support a causal interpretation of treatment-outcome associations, we will statistically control confounding by indication and estimate dose-response relationships. Bayesian hierarchical regression models will allow reliable estimation of effects for different treatment patterns, and variation of treatment effects between sub-groups. The project is implemented by an interdisciplinary \& international team of researchers from psychology, psychiatry, pedagogy \& statistics. An advisory board with stakeholders will ensure scientific impact and clinical relevance.