Imagine suffering from the crushing weight of major depression, then finally getting diagnosed and starting treatment with a drug—only to realize after two months that the medication, despite its unpleasant side effects, is not alleviating your depression. Unfortunately, this experience is far from rare: more than two thirds of patients with depression have no luck with the first medication they are prescribed and must also endure the withdrawal effects that come with discontinuing a drug before trying a new one. Finding the right treatment can prove a lengthy, painful process of trial and error. A new technology, however, may bypass this ordeal by gauging very early in a treatment regimen how well a drug is working based on the patient’s brain waves.

The technology, called quantitative electro­enceph­alography (QEEG), measures a person’s brain-wave pattern with EEG and then compares it with a database of normal samples to detect abnormal function. In a study published in the September 2009 issue of the journal Psychiatry Research, scientists used QEEG to record brain activity in subjects with major depressive disorder before they began treatment, after one week on an antidepressant and after eight weeks on the drug—the period it takes such drugs to achieve full effect. Changes in the QEEG readout after just one week of medication predicted 74 percent of the time whether patients would experience either a recovery or a remission of symptoms by the end of eight weeks.

“There appear to be changes in brain electrical activity that occur as early as a week, when the patient isn’t feeling any different,” says Andrew Leuchter, a psychiatrist at the University of California, Los Angeles, and lead author of the study. The result “proved [this QEEG-based technique] was in the range of something that could be useful to patients,” he states.

Further research is needed to verify the technique’s promise, so Leuchter estimates it may be several years before QEEG can be used in the clinic. Still, the technique presents a much needed way to judge a drug’s efficacy, says psychologist D. Corydon Hammond, a pro­fessor at the University of Utah School of Medicine, who was not involved in the study. “Psychiatry has been in drastic need of more scientific and objective methods for medication selection for years,” Hammond says. He praised the study as “important” and added, “Many more like it are needed and with other conditions besides depression.”