Images of the brain's fastest signals reveal an electromagnetic marker that predicts a patient's response to a fast-acting antidepressant, researchers have discovered.
"Such biomarkers that identify who will benefit from a new class of antidepressants could someday minimize trial-and-error prescribing and speed delivery of care for what can be a life-threatening illness," said Carlos Zarate, M.D., of the National Institute of Mental Health (NIMH), Mood and Anxiety Disorders Program.
In the new study at the National Institutes of Health in Bethesda, MD, depressed patients showed increasing activity in a mood-regulating hub near the front of the brain while viewing flashing frightful faces the more the increase, the better their response to an experimental fast-acting medication called ketamine. By contrast, healthy controls showed decreasing activity in this brain area under the same conditions.
Zarate, Giacomo Salvadore, M.D., Brian Cornwell, Ph.D., and NIMH colleagues report on their discovery online in Biological Psychiatry September 24, 2008.
Two years ago, Zarate and colleagues reported that ketamine, which targets the brain chemical glutamate, can lift depressions in just hours, instead of the weeks it takes conventional antidepressants, which work through the brain chemical serotonin. Evidence suggests that glutamate likely acts closer to the source of the depression than serotonin, and is not dependant on slower mechanisms, such as the synthesis of new neurons.
Earlier imaging studies with conventional antidepressants had hinted that increased activity of the mood-regulating hub, called the anterior cingulate cortex (ACC), signals a better response.
To find out if ACC activity might also forecast response to glutamate-targeting medications, the NIMH researchers imaged the brain activity of 11 depressed patients and 11 healthy participants, using magnetoencephalography (MEG). This
|Contact: Jules Asher|
NIH/National Institute of Mental Health