A “depression risk” gene identified more than 5 years ago may not be linked to the mental illness after all, a new study reports.
Scientists believe that most mental disorders are caused by a complex interaction between genes and the environment. But it’s difficult to detect their precise roles.
In 2003, researchers thought they’d found a gene, the serotonin transporter gene, that affects the risk of major depression in people who’d experienced several stressful events. But follow-up research by other scientists raised questions about the 2003 study’s findings.
To take a closer look, scientists from NIH and 6 universities reviewed research studies that had looked into the connection. The team re-analyzed data on over 14,000 participants in 14 studies of depression and the serotonin transporter gene.
The researchers found a strong link between the number of stressful life events and the risk of depression. But the serotonin transporter gene seemed to have no effect on the risk for major depression, alone or in interaction with stressful life events.
Scientists note that it can be hard to distinguish between the modest effects of certain genes and the impact of environmental factors, like stressful life events. That’s why it’s important to conduct follow-up research to see if the results hold up with further study.
“We are still in the early days of understanding how genes and environment interact to increase the risk for depression,” says Dr. Thomas Insel, director of NIH’s National Institute of Mental Health.