A diagnostic profile that is slowly converging
Children and adolescents in Denmark who receive a diagnosis of attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder (ASD) today share more characteristics with their peers in the general population than those diagnosed a decade earlier, according to a study led by the Barcelona Institute for Global Health (ISGlobal) and Aarhus University. The findings, published in JAMA Psychiatry, suggest that the widely reported rise in diagnoses over the past ten years may partly reflect a change in who is being diagnosed, not only a change in how many people genuinely develop these conditions.
For years, research has consistently shown that certain traits appear more often among people diagnosed with ADHD or ASD than among the population at large. Those traits span the prenatal period, the family environment, and the health care trajectory that precedes a formal diagnosis. The new work asks a straightforward but rarely tested question: do the people receiving these diagnoses still look like the people who received them in the past?
The characteristics researchers tracked
- Pregnancy- and birth-related factors, including preterm birth and low birth weight
- Family and socioeconomic circumstances, such as lower parental education or household income
- A parental history of psychiatric disorders
- Greater use of health care services in the period before a diagnosis was recorded
Each of these markers has historically been associated with a higher likelihood of an ADHD or ASD diagnosis. What the researchers wanted to know was whether that association has weakened as diagnosis rates have climbed.
Two million children and a decade of records
To find out, the team analyzed data covering more than 2.1 million children and adolescents living in Denmark. They compared more than 71,000 individuals diagnosed with ADHD or ASD between 2012 and 2022 against a comparison group of more than 713,000 peers who did not receive either diagnosis.
The headline result did not overturn the established pattern. Children and adolescents with a diagnosis were still more likely than their peers to have been born preterm or at low birth weight, to come from households facing socioeconomic disadvantage, or to have a parent with a psychiatric history. But the size of those differences contracted steadily across the study period, in some cases dramatically.
How the gaps narrowed
Low birth weight offers the clearest illustration. At the beginning of the study window, children born with low birth weight were 54% more likely than children born at a normal weight to later receive an ADHD or ASD diagnosis. By the end of the period, that elevated likelihood had fallen to 17%. Similar reductions were observed for preterm birth and for several indicators of socioeconomic disadvantage.
In practical terms, the statistical distance between diagnosed children and their typically developing peers has shrunk, even though it has not disappeared. A risk marker that once stood out sharply to clinicians — a complicated birth, a family under financial strain, an existing parental diagnosis — now carries considerably less discriminating power than it did a decade ago.
Why this matters for rising diagnosis rates
Diagnosis counts for both ADHD and autism have risen in many countries over the past decade, fueling a long-running debate about whether more children are genuinely affected, whether awareness and screening have improved, or whether both forces are operating at once. The Danish analysis points to a third element: the composition of the diagnosed group itself appears to be drifting toward the profile of the general population.
If diagnoses are increasingly being assigned to children who might previously have gone unrecognized — those without the birth complications, family histories, or socioeconomic risk markers that once drew clinical attention — then part of the apparent increase could reflect broader detection rather than a uniform rise in underlying risk. The researchers are careful on this point, describing changes in the characteristics of diagnosed individuals as a plausible contributor alongside possible changes in the actual risk of developing these conditions.
What the study can and cannot show
The analysis is observational and based on population registries, which means it can document patterns and associations but cannot establish cause and effect. It cannot say why the profile of diagnosed children has shifted, only that it has. Several explanations are compatible with the data: wider public awareness, changing clinical guidelines, earlier identification in schools and primary care, or a genuine broadening of the population that meets diagnostic criteria.
Denmark's universal health system and detailed national registries make it an unusually rich setting for this kind of research, allowing researchers to link birth records, family data, and health care contacts at scale. That same strength is also a limitation. Countries with different diagnostic practices, insurance arrangements, or levels of clinical awareness might see a different trajectory, and the findings should not be assumed to transfer directly elsewhere.
What it means for families and clinicians
The results do not imply that ADHD or autism are becoming less substantial conditions, nor that risk factors such as preterm birth no longer matter. They indicate something narrower and more useful: the group of children who end up with a diagnosis is becoming more representative of childhood in general. That has implications for how clinicians weigh risk. Relying heavily on a familiar set of red flags may miss a growing share of children who do not fit the older profile.
For parents, the message is less about individual risk than about context. The shifting profile helps explain why diagnosis figures can climb without a matching rise in any single biological cause. It also underscores that a diagnosis is the product of a child, a family, a school system, and a health service interacting — not a fixed biological threshold that everyone crosses in the same way.
The takeaway
Across more than 2.1 million Danish children and a decade of records, the line separating diagnosed children from their peers has become noticeably fainter. Children diagnosed with ADHD or autism today are more like the general population than the children diagnosed ten years ago. That single observation reframes part of the debate over rising diagnosis rates, suggesting that who receives a diagnosis is changing at least as much as how many do.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
