The overdiagnosis of depression
"Depressed? No, you’re suffering from modern life," was the headline of a Daily Express article. The BBC, Daily Mail and The Daily Telegraph reported the same story: that an expert has said too many people are being diagnosed with depression when they are merely unhappy.
The sources reported that Professor Gordon Parker of the University of New South Wales, Australia, ascribes this to a lack of a reliable diagnostic tool and to marketing of anti-depressants by drug companies.
Most of the news sources, reported that the journal in which this opinion piece appeared also published a counter-argument from another expert, Professor Ian Hickle. He argued the opposing view, that depression is not overdiagnosed, and that increased diagnosis has led to benefits such as reduced suicides and increased productivity from those who are treated.
These stories are based on two opinion pieces from experts in the field of psychiatry, which argued for and against the suggestion that depression is currently overdiagnosed. Although most newspaper stories do refer to both opinions in their main text, and the BBC and the Telegraph delivered a balanced report on both arguments, all the headlines relate to the opinion that depression is overdiagnosed or inappropriately diagnosed. This may create an unbalanced view of the balanced arguments that were presented in the opinion pieces.
Where did the story come from?
The opinion pieces were written by Professor Gordon Parker from the University of New South Wales and Professor Ian Hickie from the University of Sydney. They were published in the British Medical Journal . Competing interests were declared.
What kind of scientific study was this?
The two papers were a "head to head" feature, where two experts in the field with opposing views put forward their opinions about a topical issue; in this case, whether depression is being overdiagnosed.
Both experts discussed their professional opinions and experience, and supported these by referencing the medical literature.
What were the results of the study?
Professor Parker suggests that changes in how depression is diagnosed has meant that too many people are now be considered to have a depressive disorder. To support this he refers to his group’s findings that in a group of 242 teachers, 79% met criteria for some level of depression. He argues that, as a result, people who are experiencing a normal feeling of low mood rather than true illness may receive treatment unnecessarily.
Conversely, Professor Hickie argued that an audit of general practice data from the UK, Australia and New Zealand does not suggest that depression is overdiagnosed. Those who are diagnosed are likely to be people with worse depression, people who ask for treatment, and those who have tried to harm themselves. He suggests that the increased diagnosis and treatment for depression has had several benefits, such as reduced stigma associated with depression, reduced suicides, and better physical health.
What interpretations did the researchers draw from these results?
Professor Parker concludes that depression is overdiagnosed, and that the “low threshold for diagnosing clinical depression risks treating normal emotional states as illness” and risks inappropriate treatment.
Professor Hickie concludes that depression is not overdiagnosed, and that “The real harm... comes from not receiving a diagnosis or treatment when you have a life-threatening condition like depression”.
What does the NHS Knowledge Service make of this study?
Both these pieces are written by experts in the field on an important issue. Both views are the opinions of the authors, based on their experience, and on their interpretation of the scientific evidence available. It is important for readers to note that there are opposing views on this issue, and they should consider both views before coming to any conclusions.
The authors’ responses to the simplified question "Is depression overdiagnosed?" are far from simple. Both agree that there is no single cause, no single diagnostic group, and no single treatment. Although many of the news stories focused on the dangers of overdiagnosis, there are also risks associated with underdiagnosis.
Sir Muir Gray says…
There are important points to be made about this debate;
- This type of debate often gives a false impression of the distance between the two positions. Both opinions are probably true as some doctors over-diagnose, whereas others under-diagnose
- Depression is diagnosed not on the doctors' impressions but against set criteria
