Incidence of ADHD diagnoses and medication initiation among children and adolescents in Norway from 2016-2024

Global trends show an increase in ADHD diagnoses and medication use. This study aimed to describe the incidence of ADHD among children and adolescents in Norway from 2016 to 2024, and to investigate sociodemographic factors associated with treatment initiation among newly diagnosed individuals. This nationwide longitudinal study used data from Norwegian health registers, including all incident ADHD cases (first diagnosis or medication) at ages 3-17 years between 2016 and 2024. Incidence rates were calculated per 1,000 individuals along with proportion initiating medication 0-3 months and 4-12 months post diagnosis. Logistic regression models were used to assess factors associated with initiation. The overall incidence of ADHD more than doubled between 2016 and 2024 (from 4.4 to 9.0 per 1,000), with 52,149 incident ADHD cases. The most pronounced increase was observed among adolescent females (14-17 years), where incidence rose from 3.1 to 11.4 per 1,000. Among 38,749 individuals diagnosed between 2016 and 2023, the proportion initiating medication within one year of diagnosis increased from 72.8% to 78.4%. Following a peak in 2021, proportion initiation within 0-3 months declined, while initiation at 4-12 months increased. Having a foreign-born parent was associated with lower odds, while older age at diagnosis and lower paternal education associated with higher odds of medication-initiation. This study documents a doubling in the incidence of ADHD diagnoses among children in Norway, and an even stronger increase among adolescent females. Medication initiation increased slightly but evolved toward a delayed approach. Sociodemographic factors, especially age at diagnosis, parental region of birth and father's education influence medication-initiation.