Recent years have seen a notable rise in autism spectrum disorder (ASD) diagnoses among Norwegian preschoolers, likely reflecting a genuine increase in children exhibiting behaviors that meet stable ICD-10 diagnostic criteria rather than changes in those criteria. Norway has maintained consistent, narrowly defined diagnostic standards since the late 1990s, with population studies estimating an ASD prevalence of around 0.9% by age 12. Differences in diagnostic systems, such as ICD-10 used in Norway versus DSM-5 or ICD-11 elsewhere, complicate international comparisons. Additionally, cultural and linguistic factors, including bilingualism and immigrant backgrounds, influence assessment outcomes and diagnostic timing. Gender disparities also exist, with boys more often and earlier diagnosed than girls, who may display subtler symptoms leading to later identification. Understanding these diagnostic trends requires considering stable criteria alongside cultural, linguistic, and gender-related influences to improve accuracy and support for all children with ASD.
