Stressed out? Blame your genes

Scientists have long believed that the tendency of experiencing stress-related disorders such as depression, post-traumatic stress disorder and obesity is inherited or is the result of traumatic events. But scientists from the Health Science Center who study depression in teens are looking into another factor—the role that changing genes play.

Subtle changes in a gene can predict how the brain reacts to stress, they found. And those genes may change over time, making some with the same genetic makeup more likely to experience stress than others.

The studies, led by the Health Science Center’s Douglas E.
Williamson, Ph.D., and Ahmad Hariri, Ph.D., from Duke University, looked at the serotonin transporter, a gene that regulates the amount of serotonin signaling that occurs between brain cells and is frequently the target for antidepressant drugs. They proved the existence of a mechanism impacting the brain that also may play a role in an individual’s reaction to stress, which may be a stronger predictor of stress than DNA sequencing.

Attached to the serotonin transporter’s DNA are chemical marks called methyl groups. They help regulate when, where and how much of the gene is expressed. This is one form of gene modification, which scientists are studying to understand how the same genetic code can produce different reactions to stress, and a wide range of cellular responses in the body.

“Our work is helping to identify the specific mechanisms that are involved in the onset of depression, which is involved in 70 percent of people with PTSD,” said
Dr. Williamson, an associate professor of psychiatry, epidemiology and biostatistics in the Long School of Medicine, and the Dielmann Chair of Genetic and Environmental Risk.

“The findings of the current study and our ongoing research are contributing to a paradigm shift in how our field examines genetic contributions to psychiatric conditions like depression and post-traumatic stress disorder. We are moving beyond simple inherited genetic sequence variation to examine what is being modified during one’s lifetime and how this may in turn be passed on to our children.”