Stress gets under our skin

Everyone experiences social stress, whether it is nervousness over a job interview, difficulty meeting people at parties, or angst over giving a speech. In a new report, UCLA researchers have discovered that how your brain responds to social stressors can influence the body's immune system in ways that may negatively affect health.

Lead author George Slavich, a postdoctoral fellow at the UCLA Cousins Center for Psychoneuroimmunology, and senior author Shelley Taylor, a UCLA professor of psychology, show that individuals who exhibit greater neural sensitivity to social rejection also exhibit greater increases in inflammatory activity to social stress.

And although such increases can be adaptive, chronic inflammation can increase the risk of a variety of disorders, including asthma, rheumatoid arthritis, cardiovascular disease, certain types of cancer, and depression.

The study appears in the current online edition of the journal Proceedings of the National Academy of Sciences.

"It turns out, there are important differences in how people interpret and respond to social situations," Slavich said. "For example, some people see giving a speech in front of an audience as a welcome challenge; others see it as threatening and distressing. In this study, we sought to examine the neural bases for these differences in response and to understand how these differences relate to biological processes that can affect human health and well-being."

The researchers recruited 124 individuals — 54 men and 70 women — and put them into two awkward social situations. First, in the lab, the volunteers completed the Trier Social Stress Test (TSST), which involves preparing and delivering an impromptu speech and performing difficult mental arithmetic, both in front of a socially rejecting panel of raters wearing white lab coats. Mouth swabs were taken before and after the public-speaking tasks to test for changes in two key biomarkers of inflammatory activity — a receptor for tumor necrosis factor-α (sTNFαRII) and interleukin-6 (IL-6).

In a second session, 31 of the participants received an MRI brain scan while playing a computerized game of catch with what they believed were two other real people. The researchers focused on two areas of the brain known to respond to social stress — the dorsal anterior cingulate cortex (dACC) and the anterior insula.

At first, the game was between all three "players." Halfway through the game, however, the research subject was excluded, leading to an experience of social rejection. The researchers then examined how differences in neural activity during social rejection correlated with differences in inflammatory responses to the TSST.

Their results showed that individuals who exhibited greater neural activity in the dorsal anterior cingulate cortex and anterior insula during social rejection in the brain scanner also exhibited greater increases in inflammatory activity when exposed to acute social stress in the lab.