More than 17 million adults in the United States will experience at least one episode of major depression this year; of those who seek treatment, only 40 to 60 percent will respond to any given first-line treatment, whether it be therapy or medication. However, researchers have found that most eventually will respond once they find the right treatment. Being able to predict who will respond to CBT, and who will not, may prove to be a valuable tool for treating depression.
"For depression, there is no single medication or therapy that has been found to work as a primary treatment for most patients," said Greg J. Siegle, Ph.D., assistant professor of psychiatry, University of Pittsburgh School of Medicine. "We found that people with depression who have increased activity in one area of the brain and decreased activity in another in response to emotional stimuli are more likely to respond to a specific treatment--cognitive therapy. If this finding holds true, we may be able to predict what therapies will be most effective for individual patients by using imaging technology, bypassing the lengthy trial and error process that is often necessary to find the right treatment."
The study used functional magnetic resonance imaging (fMRI) to identify which areas of the brain were active or inactive when exposed to a negative stimulus. While undergoing fMRI, 14 unmedicated participants with depression and 21 control subjects who had never reported symptoms of depression were presented with emotional words and asked if those words applied to them. The participants with depression then completed 16 sessions of CBT over 12 weeks as part of a larger clinical trial.
Researchers found that compared to controls, nine of the participants with depression had decreased activity in a region of the brain called the subgenual cingulate cortex after they read negative words. Of those nine, seven recovered from their depressive symptoms after CBT. Only one of the five participants with depression who did not demonstrate decreased activity in the subgenual cingulate cortex recovered after CBT. Better recovery also was associated with increased activity after reading negative words in a brain region called the amygdala.
"The amygdala helps us to recognize things as being emotional. In some people with depression, the amygdala doesn't turn off as fast as it should after it recognizes something as being negative. The subgenual cingulate cortex regulates emotions and plays a part in turning the amygdala on and off," said Dr. Siegle. "If the amygdala doesn't get 'turned off' in a person with depression, when exposed to negative information, the person may ruminate, going over this information again and again. Cognitive behavioral therapy teaches people techniques to stop this rumination, so it makes sense that it would be a good treatment option for those people who can't turn off their amygdala," said Dr. Siegle.
The Pittsburgh researchers have recently received funding from the National Institute of Mental Health (NIMH) to replicate this study in a larger group of people. Additionally, they hope to evaluate the participants after they complete a course of CBT to determine what changes occur in their brains.
This study was funded by NIMH, the National Alliance for Schizophrenia and Depression (NARSAD), and the Veteran's Research Foundation.
In addition to Dr. Siegle, co-authors of the paper are Michael E. Thase, M.D., professor of psychiatry, University of Pittsburgh School of Medicine; and Cameron S. Carter, M.D., professor of psychiatry, University of California, Davis, formerly with the University of Pittsburgh.