Mental illness diagnosis needs a major revision, study warns

10 Oct 2019

Image: © VadimGuzhva/

Researchers led by TCD have published findings that suggest our current methods of mental illness diagnosis are too broad to be accurate.

A study published to JAMA Psychiatry has determined that mental illness diagnosis is in serious need of an overhaul as the current system might not accurately reflect a person’s underlying neurobiology.

This finding was made by a team of researchers led by Dr Claire Gillan of Trinity College Dublin (TCD), determining that a far more individualised approach is needed to define mental illness.

In the study, the team showed that a compulsive dimension of mental health maps onto various aspects of ‘cognitive flexibility’ better than current expert-assigned diagnosis. Cognitive flexibility reflects a set of brain processes that are thought to be essential for controlling our habits.

It was previously known that habits play a significant role in mental health conditions represented by compulsive, repetitive behaviours. In this study, the focus was on obsessive-compulsive disorder (OCD) but others may include binge-eating and other forms of addiction.

More individual treatments

Currently, mental disorders are defined in terms of diagnostic and statistical manual (DSM) diagnoses, in which a patient is either labelled as being within the criteria or not. This yes or no answer is an important part of making clinical decisions, the team said, but might be missing the reality of mental illness.

A current rework of diagnosis is needed, it added, because there is substantial overlap across disorders where patients could meet the criteria for a number of different disorders, many of which could share commonalities. This latest study showed that it could be possible for two patients to be given the same diagnosis but have little to no overlapping symptoms, and even though they might respond in entirely different ways to the same treatment.

When it comes to OCD, the study suggested self-reported levels of compulsive behaviour are a better predictor of alterations in cognitive flexibility than whether someone has a diagnosis of OCD.

Speaking of the findings, Gillan said: “By defining mental health and illness in a way that is true to the biology of the brain and respects the reality that most mental illness varies in the population, it is hoped that we are charting a path towards a future where treatments can be prescribed on a more individualised basis, based on well-defined brain systems and circuits and, crucially, with a higher rate of success.”

Colm Gorey was a senior journalist with Silicon Republic