Researchers have known for years that psychological trauma that results in post-traumatic stress disorder (PTSD) or depression can change how a person responds to stress. Now, Cornell researchers report that rapes, sudden deaths of loved ones, life-threatening accidents and other such traumas may result in long-term changes even if the survivor doesn't develop a clinical disorder.

"The findings suggest that there may be persistent differences in the stress response in some trauma-exposed people, even if they do not exhibit PTSD or depression or both, and even if their trauma was years in the past," said Barbara Ganzel, Cornell M.S. '99, Ph.D. '02, a lecturer in human development in Cornell's College of Human Ecology.

Ganzel led a team of Cornell researchers, whose study is published in a special issue of the Journal of Traumatic Stress on the biology of trauma. They assessed a group of women before and after they took their medical admissions tests (MCATs), a stressful experience for most people. Measuring levels of a stress hormone in saliva (cortisol), they found that women who had experienced trauma earlier in life (but who did not have PTSD or major depression) had lower levels cortisol leading up to and after the MCAT exam.

In addition, they found that the women who had experienced trauma kept a negative mood after the test, compared with other women, whose moods lifted significantly after the exams.

Ganzel suspects that the stress response system in these women have compensated or changed over time. The trauma-exposed women showed lower rather than higher levels of cortisol, Ganzel theorized, because "stress initially boosts cortisol output but after the stressor is over, cortisol falls below normal. These data suggest that, in some people, it may fall below normal and stay there, or that it develops a chronic tendency to dip lower than normal under stress."

The other co-authors are John Eckenrode, Pilyoung Kim, Elaine Wethington, all in human development at Cornell; Eric Horowitz '07; and Elise Temple, formerly of Cornell and now at Dartmouth College.

The research was supported by the College of Human Ecology, the Family Life Development Center and the Laboratory for Developmental Cognitive Neuroscience at Cornell, as well as by the National Institute of Mental Health.