—Marc Caron, Ph.D., Duke University Medical Center (2005 Distinguished Investigator, NARSAD Scientific Council member), led a research team that discovered a genetic variation that may predispose people to developing major depression. This same gene may also cause those who suffer from depression to be less responsive to the selective serotonin reuptake inhibitor drugs (SSRIs) commonly used to treat it. The findings of the study were recently published in Neuron magazine and highlighted in the New York Times.

Although the serotonin system is not yet fully understood, higher serotonin levels are associated with better mood states. SSRI antidepressant medications (such as Prozac and Zoloft) extend the action of serotonin in the brain and often help those suffering from depression.

Dr. Caron’s team identified a mutation in the gene TPH2 that greatly reduces the amount of serotonin produced by the brain. Dr. Caron pointed out that, “Abnormalities in brain levels of serotonin have been widely suspected as a key contributor to major depression and other neuropsychiatric disorders. Our findings provide a novel molecular mechanism underlying dysfunction in serotonin neurotransmission in some patients with depression.”

Thomas Insel, M.D., director of the National Institute of Mental Health and former NARSAD Scientific Council member (and a 2001 Distinguished Investigator) commented on the study as well. “[The results] suggest that we may be able to personalize the treatment of depression”, said Dr. Insel.

The research team noted that additional large-scale genetic studies are needed to confirm the findings and further investigate the connection between a mutated TPH2 gene and major depression.