Danish children diagnosed with autism or ADHD in the latest years of the record resemble the general population more closely than those diagnosed a decade earlier, according to a registry study from the Barcelona Institute for Global Health (ISGlobal) and Aarhus University. Among 2.1 million children and adolescents followed, the researchers set 71,000 who received an ADHD or autism diagnosis between 2012 and 2022 against 713,000 peers who were never diagnosed.
Pooled cohorts, a Danish register and a ten-year gap
The finding belongs to autism and ADHD together, not to autism alone. The paper, published in JAMA Psychiatry in September 2026, treats the two as one diagnosed group, and the summaries of it do not break out autism on its own. Any statement about newly diagnosed autistic children is therefore a statement about a pooled group in which they are included, and the cohorts are Danish: the comparison is between children diagnosed around 2012 and children diagnosed around 2022 in one country’s health registers, not a worldwide trend.
The authors, led by Magnus Elias Tarp with Oleguer Plana-Ripoll as senior author, asked a specific question: which early-life and family characteristics singled out the children who got a diagnosis, and did those characteristics change between the start and end of the decade? The institutions’ own release puts the result plainly: children and adolescents diagnosed in Denmark today share more characteristics with their peers than those diagnosed a decade ago.
Low birth weight and the narrowing gap
The clearest illustration in the study is birth weight. In 2012, children born with low birth weight were 54 percent more likely to receive an ADHD or autism diagnosis than other children. By 2022 the figure was 17 percent, as SciTechDaily’s account of the paper describes it.
Preterm birth followed the same direction, with a weaker association in the later cohort than the earlier one, and so did socioeconomic disadvantage, measured through markers such as parental education and household income. Each of these used to separate diagnosed children from the rest of the population more sharply than it does now, according to the researchers’ comparison of the 71,000 diagnosed children with the 713,000 who were not diagnosed across the decade. In plain terms, a child’s start in life now says less about who ends up with a diagnosis than it did at the beginning of the period, which is what “looking more like the general population” means in the study’s terms.
Plana-Ripoll, quoted in the same account, said that greater awareness of ADHD and autism, better identification by health and educational services and broader access to assessments may all play a part, and the researchers also point to possible shifts in diagnostic thresholds over time. The word “may” belongs to the authors: the study documents a change in who is diagnosed and does not test which of these explanations is correct.
Denmark-only data and the missing autism-only figures
The authors are explicit that the result is no verdict on overdiagnosis and no sign that cases have become milder. The population receiving these diagnoses has changed over time, and that is the full claim. The team’s own reading is that the risk factors are still important, and the finding does not say they have stopped mattering.
Outside experts, gathered by the Science Media Centre, added caution. Steven Kapp of the University of Portsmouth noted that the study did not measure the degree of core traits or disability. Joanna Martin of Cardiff University said the results are likely to be relevant to the United Kingdom as well, and stressed that the impact of symptoms had not necessarily decreased. Dame Uta Frith of University College London observed that the proportion of mild cases appears to be increasing, and called for severity measures to confirm whether milder presentations are becoming more common.
A separate Danish analysis in European Child and Adolescent Psychiatry, led by Bliddal and colleagues, tracked 2.8 million children from 2000 to 2024 and found both conditions rising over two decades, with autism reaching a cumulative incidence by age 18 of 6.5 percent in boys and 3.9 percent in girls, according to the Region Hovedstaden research portal.
A second JAMA Psychiatry paper from Region H researchers in Denmark, on polygenic scores, reached a compatible conclusion, supporting broadening diagnostic criteria as an explanation for increasing rates, according to its news release. Two different research teams working from Danish data therefore point toward a widening of who is diagnosed, though neither establishes what any individual child’s diagnosis reflects.
Still open is whether the pattern holds outside Denmark and whether autism, taken by itself, shows it as strongly as ADHD does. The paper’s pooled design cannot answer the second question, and the published summaries do not report the autism-only numbers that would.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
More from Morning Overview
- Card skimmers hidden on gas pumps and ATMs are draining accounts, and here’s the tell
- Hurricane Hunter radar shows four warning signs that a tropical cyclone is about to strengthen, a University of Miami study found
- NTSB report details how a family of four died when their plane’s nose suddenly pitched up
- Doctors warn a silent liver disease now affects one in three American adults
