ADHD diagnoses rise as milder cases are identified

Danish researchers have found that the surge in ADHD diagnoses over the past two decades appears to include more people with milder symptoms, according to a study published in JAMA Psychiatry.

The study, led by researchers at the University of Copenhagen, analyzed genetic data from over 37,000 individuals diagnosed with ADHD or autism in Denmark between 1994 and 2016. It revealed that those diagnosed closer to 2016 had a lower genetic risk for the conditions compared to those diagnosed in 1994—about 10 to 15 percent lower for ADHD and up to 25 percent lower for autism.

Senior author Andrew J. Schork, an associate professor at the university’s Department of Neuroscience, said the findings suggest a broader group of people, including those on the milder end of the spectrum, are now being diagnosed. He attributed this to increased awareness of ADHD and autism symptoms.

Per Hove Thomsen, a professor of child and adolescent psychiatry at Aarhus University, called the study robust and noted that it indicates diagnoses are now being given to individuals with lower genetic risk who still meet the criteria for ADHD or autism, not just the most severe cases.

However, the study does not address whether symptoms are less severe in those diagnosed more recently, nor does it comment on potential overdiagnosis. Schork emphasized that all diagnosed individuals still had an elevated genetic predisposition, and the decline in risk was not rapid enough to suggest irresponsible diagnostic practices.

Niels Bilenberg, a professor of child and adolescent psychiatry at the University of Southern Denmark, said the research raises questions about whether more people with milder symptoms are being diagnosed and whether they could receive help without a formal diagnosis. He noted that ADHD is a spectrum disorder, with a blurred line between deviation and normal variation.

Bilenberg, a child psychiatrist since 1994, argued that society should be better at accommodating differences without requiring a diagnosis, as access to support—particularly in schools—often depends on having one.