Australian researchers are questioning the effectiveness of antidepressants, after a clinical study suggested many might be taking them unnecessarily.

Researchers at the University of Melbourne have found that the gap between placebos and antidepressants is closing.

They say this means it is likely that patients with depressive symptoms tend to recover over time, irrespective of treatment. The medicines still have a role in treating depression, they add, but the industry might need to think about new means to combat the lower effectiveness.

“Antidepressants are the most commonly used treatment [for depression], taken by 10 per cent of adult Australians each day, and at a rate that has more than doubled since 2000 to be among the highest in the world,” according to Dr Christopher Davey and Professor Andrew Chanen’s new report.

The release of the first selective serotonin reuptake inhibitors (SSRIs) in the 1980s encouraged people to think of depression as a chemical imbalance that needed to be corrected with medication.

But the increasing placebo response could be behind falling effectiveness, as studies show the gap between response to medications and placebo narrowing.

“The placebo response is a complicated phenomenon. In part, it is driven by a positive expectation bias, but it also illustrates the statistical concept of regression to the mean, whereby patients with depressive symptoms at baseline tend to recover over time irrespective of treatment,” the authors explained.

Other treatments for depression also have modest effects, with psychotherapies such as cognitive behavioural therapy and interpersonal psychotherapy similarly showing declining effectiveness in recently published trials.

Although the latest evidence may have tempered the initial enthusiasm for antidepressants, they still have a role in treating depression, the authors say.

Combining different treatments is one way to combat lowering effectiveness.

“The combination of psychotherapy and medication is more effective than either alone,” the authors write.


They say all patients should be offered psychotherapy where it is available, and medication should be considered if:

  •  the depression is of at least moderate severity
  •  psychotherapy is refused
  •  psychotherapy has not been effective

Alongside these treatment strategies, the authors say good eating and exercise are always valid recommendations to help encourage a healthy mind and body.

Their paper is published in the AMA’s journal MJA.