US researchers claim to have found a way to predict if antidepressants or psychotherapy will work best for depressed patients. Though not yet in use, the scientists said a brain scan of depressed patients' insular cortex could show doctors whether psychotherapist or antidepressants are the most effective treatment.

Located just above the ear, the insular cortex, or insula, plays a role in influencing emotional life and was key to research conducted by the team at Emory University in Atlanta, Georgia.

According to their study, patients whose insula consumed an excess of glucose benefitted most from cognitive behavioral therapy, a form of psychotherapy. In patients whose insula were less active and thus consumed less glucose, antidepressants were more successful.

"If verified with prospective testing, the biomarker defined in this study provides the first objective marker, to our knowledge, to guide initial treatment selection for depression," Helen Mayberg and her colleagues wrote.

Two different kinds of depression?

The results are "interesting food for thought," said Wolfgang Maier, psychiatrist at University Hospital in Bonn, adding that they should not be overrated. "This is only a small study." The researchers tested 67 patients, but their analysis based on only 38 of them - the patients who didn't fit into the pattern were excluded.

Mayberg and her colleagues speculated that two forms of depression exist which can be treated either with antidepressants or with psychotherapy.

"This hypothesis is dangerous because it rattles a current theory," Maier said, adding that the best treatment of a severe depression is currently understood to be a combination of psychotherapy and medication. "If the researchers are right, patients shouldn't gain any benefit from a combined therapy."

In case of severe depression, a doctor should always prescribe medication as well as psychotherapy

A doctor's choice

At the moment there is no way to determine in advance which therapy will work best with an individual patient. Treating depression is more or less trial and error with fewer than 40 percent of all depression patients getting better after the initial treatment.

The guidelines for treating depressions in Germany state that a severe depression should be treated with both psychotherapy and medication while mild cases of depression should not be treated with drugs.

"But in reality these guidelines aren't followed to 100 percent," Maier said, adding that what kind of treatment patients receives often depends on where they go to seek help. "A psychotherapist will prescribe psychotherapy. A general practitioner and a psychiatrist will probably prescribe antidepressants. In a hospital, the patient will probably get both."

Antidepressants on the rise

Since 1994 antidepressants use in Germany has risen more than fourfold. And it is still rising: Between individual years it increases on average by 10 percent.

Some people warn that these drugs are overused. Dieter Best, chair of the Union of German Psychotherapists, said, "Especially with older women, general practitioners prescribe antidepressants like a shot in the dark, often without even generating a diagnosis first."

Every fourth woman above 80 years takes antidepressants, according to Best. "But often these women are just lonely," he said.

General practitioners should take the time to talk to their patients and the patient's relatives, have a well-founded diagnosis and send them to a psychiatrist if they aren't sure, he said. "Not everyone who feels blue is depressed."

Doctors often prescribe antidepressants without having a well-founded diagnosis

A placebo effect?

In 2008, Irving Kirsch of University of Hull and his colleagues wrote in the journal "Plos Medicine" that the effect of antidepressants is just a little higher than that of placebos. Often patients' belief in them helps, not the drug itself.

Some people even say that economic interests of pharmaceutical companies are the true reason why antidepressants are on the rise.

Maier, however, did not agree, "Antidepressants are effective drugs to treat a functional disorder of the brain."

Antidepressants lower the risk of a suicide, writes the German Society for Psychiatry, Psychotherapy, Psychosomatic Medicine and Neurology on its website.

But for every patient the benefits and the risks of the medication have of course to be balanced, Maier said. A regular contact between patient and doctor is essential. "As is the case for all other drugs and therapies."