ADHD and Autism Diagnoses Show Shifting Demographics in Denmark

Children diagnosed with attention deficit/hyperactivity disorder (ADHD) or autism spectrum disorder (ASD) in Denmark now more closely resemble the general population than those diagnosed a decade ago. This is according to a study of over 2.1 million young people. The Barcelona Institute for Global Health (ISGlobal) and Aarhus University led the research.

The findings suggest that increased diagnoses may reflect broader identification and changing diagnostic patterns. This occurs alongside any potential increase in the underlying conditions. The study was published in *JAMA Psychiatry*.

Researchers analyzed data from more than 2.1 million Danish children and adolescents. They compared over 71,000 young people diagnosed with ADHD or ASD between 2012 and 2022 with over 713,000 individuals without either diagnosis. Previously identified characteristics, such as premature birth, low birth weight, and parental socioeconomic factors, were more common in diagnosed individuals. However, the differences between diagnosed and undiagnosed groups narrowed over the study period.

For example, children born with low birth weight were 54% more likely to receive an ADHD or ASD diagnosis at the beginning of the study. This difference dropped to 17% by the end of the study. Similar declines were observed for premature birth and socioeconomic disadvantages. This indicates that individuals receiving diagnoses in recent years are more similar to the general population.

The study does not conclude that these conditions are being overdiagnosed or have become less severe. Instead, it suggests that the population receiving these diagnoses has changed over time. Increased awareness, improved healthcare and education system identification, and expanded access to diagnostic evaluations may contribute to this shift. These findings could influence how scientists interpret changes in prevalence and plan healthcare and educational services.