April 27 (UPI) -- A worldwide research project has identified 44 genetic risk factors for major depression, including 30 new discoveries.
The study by the Psychiatric Genomics Consortium, which included more than 200 scientists, is the largest mapping of genetic risk factors for major depression. The findings were published this week in the journal Nature Genetics.
"With this study, depression genetics has advanced to the forefront of genetic discovery," Dr. Gerome Breen, from the Institute of Psychiatry, Psychology & Neuroscience at King's College London said in a press release. "The new genetic variants discovered have the potential to revitalize depression treatment by opening up avenues for the discovery of new and improved therapies."
The scientists hope to find out why half of patients don't respond favorably to antidepressant treatments.
In their research, they found the genetics behind major depression are shared with psychiatric disorders including schizophrenia. And they found that a higher body mass index, or BMI, is linked to an increased risk of major depression.
Major depression is characterized by changes in mood, and cognitive and physical symptoms over a two-week period. About 8 percent of American adults had depression in a given two-week period, according to the Centers for Disease Control and Prevention.
All humans carry at least some of the 44 genetic risk factors.
The researchers, by combining seven separate datasets, identified more than 135,000 people with major depression and more than 344,000 controls. The data came primarily from people of European descent, but researchers contrasted European results with a study of depression and genetics in Han Chinese population.
"This study has shed a bright light on the genetic basis of depression, but it is only the first step," Dr. Cathryn Lewis of King's College London said. "We need further research to uncover more of the genetic underpinnings, and to understand how genetics and environmental stressors work together to increase risk of depression."
The scientists are developing an online tool by the fall to allow volunteers with depression to take part in further genetic studies.
The study was led by the University of North Carolina School of Medicine and the University of Queensland in Australia. The Psychiatric Genomics Consortium began in 2007 and includes more than 800 investigators from 38 countries.