Saliva Test May Predict How Body Reacts to Stress

Saliva Test May Predict How Body Reacts to Stress

Scientists from the University of Texas Health Science Center at San Antonio (UTHSCSA), Duke University, Columbia University, and the University of Pittsburgh who were studying depression in teens have discovered that subtle changes in a gene can predict how the brain will react to stress. These changes, they speculate, can lead to serious health conditions—including depression and obesity. In “Beyond Genotype: Serotonin Transporter Epigenetic Modification Predicts Human Brain Function,” published online in August by Nature, the authors point to the serotonin transporter gene as a promising predictor of stress.

By regulating the amount of signaling between the gene and brain cells, the serotonin transporter impacts how people handle stress. Previous theories on stress and stress-related disorders theorized that they were inherited or caused by a traumatic event. Now researchers believe that genes continue to change, with some people becoming more susceptible to stress over the course of their lifetimes.

One way to monitor this gene change is through saliva testing. In the study, the team performed brain imaging on 80 subjects. Responses in the amygdala—the bundle of neurons located deep in the brain’s medial temporal lobe—were recorded as participants were shown angry and fearful faces. The researchers then sampled the presence of methylation, a form of gene modification, on serotonin transporter DNA from the subjects’ saliva. Analysis revealed that even a slight change in methylation corresponded with activity in the amygdala and appeared to be a better predictor of depression risk than inherited genetic sequence variation.

The scientists theorize that exposure to stress over time produces changes in methylation. “The study’s findings and our ongoing research are contributing to a paradigm shift in how our field examines genetic contributions to psychiatric conditions, such as depression and post-traumatic stress disorder,” notes Douglas E. Williamson, PhD, director of the genetic epidemiology program at UTHSCSA and one of the study’s authors. “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.”

The researchers hope that this discovery, with the support of ongoing study, will eventually help reduce the risk of depression and other stress-related disorders.

Hygiene Connection E-Newsletter

September 2014