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Mental rehearsal of past stressors through rumination may extend the physiological stress response and exposure to stress-related physiological mediators, such as cortisol. If repeated over time, this prolonged activation may contribute to a number of chronic health conditions. Findings from the emerging literature on the tendency to ruminate and its association with cortisol have been somewhat mixed. In the present study, we tested whether trait rumination predicted elevated cortisol concentrations in response to a performance stressor, and whether this association varied by the social-evaluative context of the stressor and gender. We also examined whether associations persisted into the evening of the stressor. Participants (50% female; mean age = 19.83, SD = 1.62) were randomly assigned to complete a laboratory speech stressor either in a social-evaluative (SET; n = 86) or non-evaluative context (non-SET; n = 58). Salivary cortisol concentrations were measured throughout the laboratory visit and later that evening. There was a main effect of trait rumination on greater total cortisol exposure into the evening of the stressor. In addition, trait rumination interacted with stressor context to predict cortisol declines: on the night of the SET stressor, high trait ruminators did not exhibit typical declines in cortisol. Different cortisol patterns emerged for men and women with tendencies to ruminate: women with higher rumination scores had flatter cortisol slopes with greater evening cortisol, whereas men with higher trait rumination scores had greater initial cortisol reactivity to the stressor. Together, these findings suggest that the relationship between the tendency to ruminate and cortisol concentrations is qualified by individual differences (gender) and stressor characteristics (social-evaluative threat).

Persistent or excessive exposure to stressors and consequent physiological changes have a range of negative health implications (for review, see Juster et al., 2010). One route to persistent activation of the stress response is through the mental rehearsal of stressful experiences, or rumination. In other words, cognitive representations of past stressful events may perpetuate stress-related physiological changes or reactivate stress responses. This conceptual model is outlined by the Perseverative Cognition Hypothesis, and there is growing empirical support for the premise that cognitive processes such as rumination can amplify, maintain, or reactivate physiological stress responses and predict greater somatic symptoms and physical health complaints (Brosschot et al., 2006). Thus far, the majority of the evidence for the association between rumination and extended related physiological activation has come from the cardiovascular domain. A smaller, but increasing body of work has begun to test this model within the context of the hypothalamic–pituitary–adrenal (HPA) axis (for review, see Zoccola and Dickerson, 2012). However, findings from the emerging literature on rumination and cortisol have been somewhat mixed. These discrepancies may stem in part from situational factors and individual differences, such as gender and the social-evaluative nature of the stressor. Rumination has been defined in multiple ways across contexts, but there is general consensus that rumination can be described as repetitive, past-oriented thoughts about negatively-valenced content (Segerstrom et al., 2003 and Smith and Alloy, 2009). Rumination is a relatively stable emotion regulation strategy and certain individuals are more prone to perseverate than others. For example, individuals who display a ruminative cognitive style of responding to sad or depressive mood consistently report this tendency over a range of time intervals (e.g., Just and Alloy, 1997 and Nolen-Hoeksema and Davis, 1999). In addition, gender differences are frequently noted, with women tending to report more rumination than men (Zlomke and Hahn, 2010). Thus, to better understand whether and how rumination prolongs cortisol elevations, it may be useful to examine individual differences in the tendency for rumination and test for gender differences. Conditions in which central goals are threatened or blocked are also important for shaping cortisol responses and ruminative thought. This is well illustrated with social self-preservation theory (Dickerson et al., 2004). According to this model, social-evaluative threat (SET) occurs when a key component of one's self-identity is actually or potentially judged in a negative way by others (e.g., rejection). In response to SET, one may engage in negative self evaluation and consequently, may experience shame and other self-conscious emotions, which in turn coordinate a specific set of physiological and behavioral responses, including HPA axis activation ( Dickerson et al., 2004). Meta-analytic and empirical studies indicate that SET preferentially elicits the HPA axis and subsequent increases in salivary cortisol ( Dickerson et al., 2008 and Dickerson and Kemeny, 2004). In contrast, mood inductions or difficult distressing tasks that lack a social-evaluative component have been less reliable methods for eliciting increases in cortisol ( Dickerson and Kemeny, 2004). Therefore, individuals who tend to ruminate on stressors may be more likely to experience prolonged cortisol exposure in response to cortisol-eliciting stressors, or SET contexts, compared to non-SET situations. Rumination may also be more likely to occur in response to a SET context. In evaluative and potentially rejecting situations, the fundamental needs of an individual are threatened (e.g., need for social belonging). Such a failure in goal attainment is expected to elicit rumination (Martin and Tesser, 1996). Consistent with this premise, recent work provides support for the notion that SET can lead to both shame and rumination (Zoccola et al., 2012 and Zoccola et al., 2008). Specifically, participants assigned to perform a SET stressor reported greater post-task ruminative thoughts than those who performed identical tasks without the evaluative component (Zoccola et al., 2008). A follow-up study confirmed these results, and demonstrated that SET effects on state rumination can persist at least 3–5 days post-stressor (Zoccola et al., 2012). Together these results suggest that stressors characterized by SET may be particularly likely to induce ruminative thought and prolong stress-related cortisol activation. Past studies that have utilized SET stressors in the laboratory to test the relationship between rumination and cortisol have generally showed that rumination predicts greater cortisol reactivity or delayed recovery (e.g., Puterman et al., 2011, Zoccola et al., 2010 and Zoccola et al., 2014), although there have also been null (Young and Nolen-Hoeksema, 2001) and mixed findings depending on the rumination measure (Gianferante et al., 2014 and Zoccola et al., 2008). Results from studies testing the link between rumination and cortisol following non-evaluative stressor tasks (e.g., anger provocation; challenging model construction) indicate that cortisol concentrations may sometimes be greater in ruminative conditions relative to comparison tasks, such as distraction ( Denson et al., 2009 and Rudolph et al., 2011). However, these studies have not demonstrated net increases in cortisol relative to pre-stressor resting values. Furthermore, the SET studies that demonstrated rumination-related elevations in cortisol during the recovery period had somewhat limited post-stressor follow-up periods (up to 75 min post-stressor). Although cortisol concentrations typically return to resting levels within the first hour following a social-evaluative psychosocial stressor ( Dickerson and Kemeny, 2004), for individuals with a tendency to ruminate, cortisol recovery may take longer ( Puterman et al., 2011 and Zoccola et al., 2010). Deviations from the normative diurnal decline in cortisol (flatter slopes) have been linked to a variety of adverse conditions, including cardiovascular disease and cancer morbidity and mortality ( Kumari et al., 2011, Matthews et al., 2006 and Sephton et al., 2000). Given the significant health correlates of flattened cortisol slopes, it is important to examine an extended recovery period to test the associations between trait rumination and diurnal cortisol declines. Another likely moderator of the rumination–cortisol association is gender. An abundance of evidence shows that men and women have different salivary cortisol patterns in response to acute performance-based stressors. Compared to women, men typically demonstrate greater increases, or reactivity, in cortisol concentrations (for review, see Kudielka and Kirschbaum, 2005). In some cases, men exhibit elevated cortisol in anticipation of an impending stressor (Ennis et al., 2001 and Kirschbaum et al., 1992). Biological differences between men and women (e.g., sex hormones) as well as psychosocial differences in gender identity (e.g., masculinity/femininity) may moderate cortisol responses to SET stressors and influence associations between rumination and cortisol concentrations. Dedovic and colleagues provide an excellent review of the evidence for synergistic biological and gender effects on neuroendocrine stress reactivity (Dedovic et al., 2009). In particular, their review indicates that differences in cortisol stress responses between men and women may be accounted for by gender socialization in early life, which in turn influence stressors appraisals, brain morphology, and HPA axis activation. Although it is beyond the scope of this project to distinguish between the unique or synergistic biological and gender effects, we examined the extent to which rumination–cortisol associations were similar or different for men and women. In doing so, we use the term gender to represent the broad social categories that encompass biological factors and psychosocial processes. In the present study, we took a novel approach by extending the post-stressor recovery window beyond the immediate laboratory stressor period into the subsequent evening. We predicted that trait rumination would be associated with elevated cortisol on the night of the stressor. We also tested whether the association between trait rumination and cortisol responses to the stressor was impacted by the social-evaluative context of the stressor (SET v. non-SET). We hypothesized that trait rumination would be associated with greater cortisol concentrations under conditions of SET (compared to non-SET), based on theoretical and empirical work (Martin and Tesser, 1996 and Zoccola and Dickerson, 2012). Finally, given the frequently reported gender differences in rumination (Zlomke and Hahn, 2010) and cortisol stress reactivity (Kudielka and Kirschbaum, 2005), we also explored the extent to which the rumination–cortisol associations were moderated by gender.