ReviewAssessing the relationship between rumination and cortisol: A review
Introduction
Stress can have profound consequences on our bodies, and an abundance of research has documented the wide range of negative effects that stressors can have on health [1]. For individuals who ruminate, or mentally rehearse past stressful events, the physiological effects of a stressor may be longer lasting. This could happen via slower physiological recovery, or longer time to turn off the response. For example, elevated levels of stress hormones may continue to circulate in the body long after an argument has ended for those who dwell on it. In addition, subsequent recall of a stressor could serve to reactivate the stress response later in time. For instance, thinking about yesterday's argument may trigger increases in blood pressure again today. Both of these pathways may lead to persistent activation of stress-related systems as outlined by the Perseverative Cognition Hypothesis [2]. The majority of evidence supporting the hypothesis that perseverative cognition, such as rumination, may prolong the physiological activation originates from the cardiovascular domain [2]. A growing body of research has also examined this model in the context of the hypothalamic–pituitary–adrenal (HPA) axis and its end-product, cortisol [3].
The HPA axis is a major stress response system that is critical for survival and adaptation, and may be particularly relevant in understanding the adverse effects stressors may have on health. Release of cortisol in response to certain stressors may be adaptive in the short term, as it leads to behavioral and physical changes to deal with the acute threat [1]. Prolonged exposure to cortisol from exaggerated, extended, or repeated activation of the HPA axis, however, may be maladaptive. Indeed, a range of disorders, including insulin resistance and cardiovascular disease, have been associated with persistent activation of the HPA axis [4]. Therefore, identifying and targeting factors, such as rumination, that may lead to excessive cortisol exposure could have important health implications.
The studies that have thus far examined the association between rumination and cortisol have produced inconsistent results. Factors contributing to the mixed findings include variability in conceptualization, measurement, and manipulation of rumination, as well as differences in cortisol assessment (e.g., basal cortisol versus cortisol responses to stressors). This review summarizes these key theoretical and methodological issues, discusses these factors in the context of the 151 published studies to date that have examined the association between rumination and cortisol, and provides suggestions for future studies in this rapidly-growing area of research. In this review, the study results have been organized by rumination measure and manipulation as well as by cortisol assessment.
Section snippets
Rumination: definition and elicitors
Rumination has been defined in multiple ways and across a variety of contexts and is largely characterized by repetitive, unwanted, past-oriented thoughts about negative content [5], [6]. Rumination is generally considered to be maladaptive in nature and it has been implicated in the exacerbation and maintenance of a variety of adverse mental health outcomes, including depression [7], social anxiety [8], and post-traumatic stress disorder [9]. Rumination is related to another perseverative
SET, rumination, and cortisol
Conditions in which central goals are threatened or blocked are also potent elicitors of cortisol. This is well illustrated with social self-preservation theory [16]. According to this model, SET takes place when an important aspect of the self-identity is or could be negatively judged by others (e.g., rejection). In response to real or perceived negative social evaluation by others, one may engage in negative self-evaluation and consequently experience shame and other self-conscious emotions
Rumination: measurement and manipulation
Rumination has been operationalized in many different ways, which could lead to different relationships between rumination and cortisol. In the following section, we review the findings from the published studies for the various measures and manipulations of rumination.
Cortisol assessment
The way in which researchers assess cortisol may also contribute to the inconsistent associations between rumination and cortisol. As already reviewed, some researchers examined cortisol concentrations in response to rumination manipulations to understand whether rumination is associated with prolonged activation. Other cortisol assessment methods have also been used, including: (a) basal, or resting, cortisol levels at a specific time of day, (b) the cortisol awakening response (CAR), and (c)
General discussion and considerations for future research
Results of the studies in this review demonstrate mixed associations between rumination and cortisol. Researchers who have examined the effects of rumination on the HPA axis have utilized a heterogeneous set of methods. Patterns of cortisol results emerged based on how researchers conceptualized rumination through measures and manipulations of rumination. In addition, methods of cortisol assessment also contributed to the variable results.
Conclusion
In conclusion, the ways in which researchers conceptualize and assess rumination and the associated cortisol response can influence the association between rumination and cortisol. Rumination may lead to prolonged activation of the HPA axis, and for those who ruminate excessively or repeatedly, these sustained elevations in cortisol may have important health consequences.
Conflict of interest
The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.
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