In two studies, saliva cortisol responses to the psychological stress of public speaking and mental arithmetic were investigated in women using oral contraceptives (OC; n = 28) and in control women (n = 29). While no significant differences in baseline levels were observed, altered adrenocortical responses were found in OC users. These women showed significantly attenuated cortisol responses to the experimental stressor in both studies, with peak cortisol levels only slightly elevated above baseline levels. These differences could not be attributed to affective responses as indicated in ratings on visual analogue scales assessing subjective stress responses (Study 2). A comparison between control women and men (n = 19) again revealed the previously reported result of larger cortisol responses to psychological stress in males. We conclude that the use of OC may interfere with the adrenocortical response to psychological stress and should therefore be viewed as an important intervening variable. While it appears that differences at a supra-adrenal site is responsible for the observed cortisol hyporesponsiveness in OC users, the physiological mechanisms remain to be elucidated.
PIP: At the University of Trier in Germany, psychologists, using data from two studies, compared saliva cortisol responses to psychological stress (5 minutes of public speaking and 5 minutes of mental arithmetic, both in front of an audience) in users of oral contraceptives (OCs) with those of women not using OCs to determine whether OCs affect cortisol levels in women under psychological stress. Controls had a higher increase in cortisol levels than OC users (p = 0.02 in study 1; p = 0.004 in study 2). In fact, peak cortisol levels in OC users were only somewhat higher than baseline levels. The subjective rating of having been nervous had a significant positive correlation with cortisol response (p = 0.018), but there was no significant association with other subjective ratings (e.g., having control over the situation). Thus, affective responses did not explain the difference in cortisol levels between OC users and women controls. When the researchers compared cortisol responses to psychological stress between female and male controls, men had a significantly greater response than women (p = 0.04). This finding confirmed the findings of an earlier report that men have greater cortisol responses to stress than women. These findings show that OCs weaken the cortisol response to psychological stress. Based on these findings and those of other studies, the authors hypothesize that OCs cause changes in the hypothalamus-pituitary-adrenal axis. Thus, estrogen-containing drugs may in the future become a prolonged treatment of supra-adrenal stimulation. The actual physiological mechanisms must be defined first, however.