Study Refutes Depression Gene Finding

June 17 -- TUESDAY, June 16 (HealthDay News) -- A new analysis upends a previous, highly acclaimed study that had concluded that a particular gene variation was associated with an increased risk of major depression.

The new analysis did, however, verify the portion of the earlier finding that showed more stressful life events translate into a substantially higher risk for depression.

"Mental disorders are the most complex of all diseases," said study senior author Kathleen Ries Merikangas, a senior investigator and branch chief of genetic epidemiology research in the Intramural Research Program at the U.S. National Institute of Mental Health. "We're learning more about how genes can control the different biologic pathways in the brain but, more importantly, how that brain is wired to respond to environmental factors. We're at the very primitive stages of knowledge."

According to the authors of the current paper, published in the June 17 issue of the Journal of the American Medical Association, the new findings call into question how research -- especially research in the mental health field -- is conducted and received.

Scientists have had an unusually tough time linking specific genes with different psychiatric illnesses, such as depression, bipolar disorder and schizophrenia. The likely reason: The genetic and environmental interactions are both more subtle and more complex than in many other diseases, said Keith A. Young, vice chair of research at the Texas A&M Health Science Center College of Medicine Department of Psychiatry and Behavioral Science.

A 2003 study published in the journal Science reported that a mutation on a gene involved in the transport of the neurochemical serotonin increased the risk of depression, but only in people who had suffered numerous stressful events.

Serotonin is a neurotransmitter known to be involved in depression and other mental illnesses. According to Merikangas, there may be as many as 40 genes governing serotonin activity.