What is already known is that post-traumatic stress disorder (PTSD), or depression, can change how a person responds to stress. What is not known is how a traumatic event effects a person even though they may not develop clinical symptoms.

Normally, when a person experiences stress their is a boost in cortisol output. After the stressful event is over the cortisol falls below normal.

Barbara Ganzel, Ph.D., a lecturer in human development in Cornell’s College of Human Ecology, decided to use an unique approach to determine if there are any long-term changes on how a person responds to stress once they have been exposed to a traumatic event like rape, sudden death of a loved one, life-threatening accident, or other such trauma.

A group of women taking their medical admissions tests (MCATs) (a stressful situation for most people) were tested for their level of the stress hormone cortisol before and after taking the MCATs. In women who had experienced a previous traumatic event, but had not developed any clinical symptoms, showed a lower level of cortisol before and after the MCAT exam.

In addition, the women exposed to a traumatic event also kept a negative mood after the test compared to the other women who had not reported a previous traumatic event.

Ganzel suspects that in some people the level of cortisol may fall below normal and stay there, or that it develops a chronic tendency to dip lower than normal under stress. How the lower levels of cortisol in stressful situations for people who have experienced a previous traumatic event is not known, but opens up a new area for investigation.