International team of researchers has discovered that brain activity differs significantly between healthy individuals and those suffering from treatment-resistant clinical depression.

Announcing their results in Biological Psychiatry, (October 15, 2003) the researchers were led by consultant psychiatrist, Professor Tonmoy Sharma, Director of the Clinical Neuroscience Research Centre in Dartford. He says: "This is a significant step in unravelling the reasons why these people may not be responding to the antidepressant drugs currently available."

The study, the most significant to date to have investigated dysfunction in different parts of the brain in treatment-resistant depression, also heralds a new era in drug development. There are already benchmark drugs for treatment-resistant schizophrenia, but there is no equivalent treatment for treatment-resistant depression at the moment. This development in the understanding of the biological basis of treatment-resistant depression gives hope to scientists searching for a much-needed "atypical" antidepressant.

Six women with treatment depression were recruited to the study, alongside six healthy female volunteers. The participants viewed a series of images that contained a picture and a caption while the researchers observed their emotional reaction using a brain imaging technique, known as functional magnetic resonance imaging (fRMI). This procedure is invaluable in tracking brain activity, and can pinpoint areas of the brain used in specific tasks.

The team found that people with depression processed their emotional response to the images differently from the healthy individuals. Some parts of the brain were less active in people with depression than the control group, while other areas showed greater activity. For instance activities in some regions of the brain, such as the rostral anterior cingulate, were reduced in people with depression compared to the healthy participants. However the team noticed that an area of the brain, the subgenual cingulate, associated with sadness in healthy people, was activated by the positive images shown to the participants with depression.