Spit may predict how we handle stress

"Have you ever wondered why adversity affects some people more negatively than others? Well, it is possible that sNGF is an important piece of that puzzle," says Douglas Granger. (Credit: Daniel Epstein/Flickr)

A component in saliva may indicate how effectively we respond to stress, researchers report.

That component—salivary nerve growth factor, a neurotrophic protein abbreviated as sNGF—is typically linked to the survival, development or function of neurons, but now may also be a marker of stress response.


“So far, sNGF appears to represent a unique facet of the way a person responds to acute stress, with individual differences in sNGF related to both short-term and more lasting measures of psychological health,” says Heidemarie Laurent, professor of psychology at the University of Oregon.

“Most importantly, sNGF responsiveness appears to be related to resilience rather than risk.”

For the study, published in the journal Psychosomatic Medicine, Laurent collected five saliva samples from 40 young adults (17 male, 23 female) twice before and three times following a stressful conflict-resolution task.

The participants were drawn from a larger study of romantic couples. Samples also were taken from a 20-member control group at the same time intervals but in the absence of the conflict scenario.

Samples were analyzed for sNGF and two other stress-linked indicators. Changes in sNGF were significant in the experimental group in response to the conflict.

The saliva was analyzed at the Institute for Interdisciplinary Salivary Bioscience Research at Arizona State University.

“The use of oral fluid as a research and diagnostic specimen has tremendous potential,” says study co-author Douglas Granger, ASU professor of psychology. “Have you ever wondered why adversity affects some people more negatively than others? Well, it is possible that sNGF is an important piece of that puzzle.”

Nerve growth factor was discovered in the 1950s by Italian neurologist Rita Levi-Montalcini and Stanley Cohen in collaborative research done at Washington University in St. Louis. They later shared the Nobel Prize in Physiology and Medicine in 1986.

Fight or flight

Much has been uncovered about its role in the brain and nervous system, but few scientists considered how NGF levels in people’s saliva might be related to the behavioral and biological components of the body’s stress response.

Conflict with a romantic partner caused sNGF to rise in parallel with the two main components of the “fight or flight” stress response—the autonomic nervous system and the hypothalamic-pituitary-adrenal axis.

Most significantly, the researchers found that the more a person’s s NGF level increased in response to stress, the lower their conflict-related negative emotions.

“This finding, suggests that an sNGF response to stress might be protective, a counterpoint to other aspects of the stress response known to negatively impact mental and physical health,” Laurent says.

“This is consistent with what we’re finding in adolescents, where higher levels of sNGF during stress are associated with lower levels of problem behaviors.”

At the time of the study, Laurent was at the University of Wyoming, which funded the research.

Source: University of Oregon