Placebo predictions.

Clinical trials of antidepressants often start with what's called a placebo lead-in phase. During this brief period, patients receive only inert pills so that their bodies will cleanse themselves of any drugs taken earlier. But placebo lead-in might also help clinicians predict how a patient will respond to actual medication, researchers now report.

Aimee M. Hunter and her colleagues from the University of California, Los Angeles studied 51 adults with major depression. All the patients took an inactive pill daily for a week without knowing it was a placebo. For the next 8 weeks, half the patients received one of two antidepressant medications, fluoxetine or venlafaxine, and the other half received more placebos. At the end of the period, Hunter's team evaluated each patient's depression with a standard clinical test. Some patients in each group had improved.

The researchers also used electroencephalography to examine each patient's brain activity before the trial and at several times during the trial.

In both groups, in patients whose depression had improved by the end of the study, neural activity had increased during the placebo lead-in phase, the researchers report in the August American Journal of Psychiatry. Whereas that change in medicated patients had appeared in the frontal lobe, patients who received only placebos showed the activity in their right temporal regions.

Clinicians could easily adopt this test, says Hunter. "It might provide information as one indicator of how well we expect a person to respond to medication," she says.