Washington, May 11 : A new study suggests that use of functional magnetic resonance imaging (fMRI) can help doctors predict whether patients with generalized anxiety disorder (GAD) would benefit from the treatment given to them or not.

For the study, the team of researchers led by Dr. Paul Whalen selected subjects diagnosed with GAD, who underwent brain scans both before and after treatment with venlafaxine, an antidepressant that is believed to be effective in treating anxiety.

During the fMRI scans, the researchers also measured the participants' responses to viewing pictures of fearful facial expressions.

"We focused our study on a regulatory circuit in the brain involving the amygdala, an area that serves to detect the presence of threatening information, and the prefrontal cortex, an area that functions to control these threat responses when they are exaggerated or unnecessary," said Whalen.

The findings revealed that about two thirds of the patients experienced relief from their anxiety symptoms after treatment, and of those who improved, some responded better than others. The fMRI data predicted who would do well on the drug and who would not.

"Subjects who showed high prefrontal cortex activation together with low amygdala activation in response to the fearful faces reported a significant decrease in their anxiety symptoms, while those showing the reverse brain activation pattern (i.e., high amygdala, low prefrontal) did not," he added.

Dr. John H. Krystal, Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, comments on this study said that there is a tremendous need for biomarkers of treatment response.

"The paper by Whalen et al. joins a small group of preliminary studies suggesting that fMRI research might contribute to the effort to develop treatment biomarkers," he said.

However, Krystal warns, "while these are exciting data, we have yet to see this type of biomarker receive sufficient rigorous validation to be useful for matching patients to existing treatments or to test new potential treatment mechanisms."

Dr. Whalen said, "future studies will be needed to determine the exact impact that brain imaging might have in helping physicians prescribe anti-anxiety medications."

The report is published in Biological Psychiatry.