MONDAY, Sept. 14, 2026 (HealthDay News) — Anyone looking for certainty in a psychiatric diagnosis may be disappointed, according to new Danish research.

“Our study shows that when two psychiatrists diagnose the same patient, they will agree only 55% of the time," said study leader Dr. Julie Nordgaard. She's a professor and consultant psychiatrist at the University of Copenhagen. 

That level of physician disagreement is "worryingly low," she said in a university news release. 

"In fact, it is similar to the levels reported in some of the studies conducted in the 1970s, which prompted the development of standardized diagnostic criteria in the first place,” Nordgaard said.

Her team published its findings recently in Frontiers in Psychology.

Guidebooks to psychiatric diagnosis, such as the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, were formulated to get practitioners literally "on the same page" in diagnosing patients.

It may not have worked, the new study found. 

In their research, Nordgaard's team first devised nine written patient case descriptions. They then presented two of these case descriptions to 1,038 psychiatrists and physicians working in psychiatry, sourced from 19 countries. 

Faced with the same case descriptions, any two psychiatrists agreed on a diagnosis only a little more than half the time, the study found.

The biggest disparities occurred for cases in the schizophrenia spectrum of illnesses.

“Cases that could be diagnosed either as schizophrenia or schizotypal disorder generated especially high levels of disagreement," noted study lead author Dr. Mateo Boberg, a PhD candidate at the university. 

"In many of these cases, agreement among participants was well below 50%,” he noted.

Boberg said confusion over diagnoses may stem from the fact that symptoms can occur across a wide variety of conditions. 

For example, obsessive thoughts can arise in both obsessive-compulsive disorder (OCD) and schizophrenia, he said.

In Nordgaard’s view, diagnostic disagreement among psychiatrists "is not about psychiatrists doing a poor job."

"Rather, it reflects the fact that, despite the existence of diagnostic systems, clinicians continue to differ in how they interpret symptoms and which features they consider most important," she said.

"We need a greater degree of consensus, otherwise patients risk receiving changing diagnoses and treatments,” Nordgaard added.

The findings could also have implications for psychiatric research, according to study co-author Mads Gram Henriksen.

“In research, it is essential that we know exactly what we are studying," said Henriksen, a professor at the university whose work combines psychiatry and philosophy. 

"If a considerable part of participants enrolled in a study on treatment of personality disorders actually suffer from schizophrenia, the study’s results become difficult to interpret," he continued in a news release. "Which condition is the treatment having — or not having — an effect on? Personality disorders or schizophrenia?”

In the new study, psychiatrists were asked to base their diagnoses on the World Health Organization's ICD-10 diagnostic system, which comprises over 200 mental disorders. That may lead to complexities that hinder accurate diagnosis, Nordgaard said.

“In our view, it is necessary to take a step back and develop more precise descriptions of psychiatric disorders so that clinicians can distinguish them more clearly," she said. "It may also be necessary to reduce the number of diagnostic categories.”

More information

Find out more on how psychiatry works at the American Psychiatric Association.

SOURCES: University of Copenhagen, news release, Sept. 9, 2026; Frontiers in Psychology, July 28, 2026