New research from Denmark reveals that increased diagnoses of autism and ADHD over the past decade may be driven more by changes in detection thresholds and access to services than by actual increases in prevalence, highlighting a shift in diagnostic practices.
New data from Denmark suggests that rising autism and ADHD diagnoses may owe as much to changes in detection and services as to changes in underlying risk, according to research published in JAMA Psychiatry. The study looked at more than 2 million children and adolescents and found that people diagnosed with either condition have, over time, become more similar to their peers without those diagnoses on measures such as birth weight and household income.
That narrowing gap matters because it points to a shift in who is being identified. Researchers reported that the differences between diagnosed children and other children weakened over the decade they studied, from 2012 to 2022. In practical terms, that implies that diagnostic thresholds, awareness and access to specialist care may be bringing in a broader group of children than in earlier years.
The findings fit with earlier work from the University of Copenhagen, which argued that Denmark’s sharp rise in autism and ADHD diagnoses reflects broader diagnostic practice rather than a simple rise in the number of people with more severe underlying impairment. The university said the study also pointed to a falling genetic contribution over the past 20 years, a result it linked to wider criteria and changing clinical behaviour.
A separate register study covering Denmark’s entire population from 2000 to 2022 found that ADHD prevalence climbed from 0.10% to 3.03% over that period. It also showed that diagnosis patterns differed by age and sex, with the highest incidence in 2022 among women aged 18 to 27 and among boys and young men aged 6 to 18. Taken together, the studies suggest that autism and ADHD trends should be interpreted cautiously: higher diagnosis rates do not necessarily mean the conditions themselves are becoming more common in the same way.
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