خوددلسوزی بعنوان پیش بینی کننده واکنش اینترلوکین 6 به استرس حاد روانی

Abstract We examined the hypothesis that self-compassion is associated with lower levels of stress-induced inflammation. On two consecutive days, plasma concentrations of interleukin-6 (IL-6) were assessed at baseline and at 30 and 120 min following exposure to a standardized laboratory stressor in a sample of 41 healthy young adults. Participants who were higher in self-compassion exhibited significantly lower day 1 IL-6 responses, even when controlling for self-esteem, depressive symptoms, demographic factors, and distress. Self-compassion was not related to day 2 IL-6 response but was inversely related to day 2 baseline IL-6 levels, and to increase in baseline IL-6 from day 1 to day 2. These findings suggest that self-compassion may serve as a protective factor against stress-induced inflammation and inflammation-related disease.

. Introduction Although modern humans are spared many of the physical stressors faced by our early ancestors, such as confrontations with predators, psychosocial forms of stress are pervasive in everyday life, from social exclusion to workplace tensions and marital conflict. When chronic, these forms of stress can be damaging to physical health. As one potential pathway, psychosocial stress has been shown to elicit an inflammatory cascade similar to that elicited by illness or injury (Segerstrom and Miller, 2004 and Steptoe et al., 2007). This biological response is theorized to have evolved to promote healing and prevent infection in wounds resulting from physical conflict (Dhabar, 1998) and, some have suggested, to promote behavioral disengagement in dangerous situations (Kemeny et al., 2004). Although properly regulated inflammation is required and adaptive in certain contexts, elevated levels of inflammation can increase the risk of a range of diseases, including cardiovascular disease, cancer, and Alzheimer’s disease (e.g., Danesh et al., 2008 and Ershler and Keller, 2000). According to social self preservation theory (Dickerson et al., 2004), psychosocial stress is especially likely to elicit increased peripheral inflammation, as well as other potentially maladaptive biological responses, when it involves threats to the self encountered in social evaluative contexts. A handful of studies provide support for the link between self-threat and inflammation. In one study, participants who performed a speech and math task in front of an evaluative audience showed increases in the production of tumor necrosis factor alpha (TNF-α) following the stressor, whereas those who performed the task alone did not show this response (Dickerson et al., 2009), suggesting that the presence of a socially evaluative audience was instrumental in eliciting an inflammatory response. A related study found that writing about a traumatic experience of self-blame, but not a neutral experience, led to increases in TNF-α receptor activity, especially among those participants reporting high levels of shame in response to the manipulation (Dickerson et al., 2004). Trait shame has also been linked cross-sectionally to higher baseline levels of the pro-inflammatory cytokine interleukin-6 (IL-6) as well as to lower glucocorticoid inhibition of IL-6 in vitro (Rohleder et al., 2008). The present research examined the hypothesis that self-compassion, a self-attitude that involves treating oneself with kindness and nonjudgmental understanding (Neff, 2003a), may be associated with lower stress-induced increases in inflammation. Self-compassion may reduce the extent to which a stressor is experienced as self-threatening, thereby attenuating the magnitude and duration of the corresponding inflammatory response. In support of this idea, prior research found that a self-compassion intervention reduced feelings of shame and self-criticism (Gilbert and Procter, 2006) and that self-compassionate individuals were less emotionally reactive in stressful situations than those low in self-compassion (Leary et al., 2007). No prior research, however, has examined the relationship between self-compassion and inflammatory responses to stress. Previous research has shown that inflammation is influenced by psychological states that are related to but distinct from self-compassion. For example, a number of studies have linked positive mood to reduced inflammation (e.g., Brouwers et al., 2012 and Sepah and Bower, 2009) and to healthy immune functioning more generally (for a review, see Marsland et al., 2007). In addition, mindfulness meditation, which involves non-evaluative attention to mental processes, has been shown to reduce stress-induced inflammation in both healthy and patient populations (e.g., Creswell et al., 2012 and Rosenkranz et al., 2013). Meditation that focuses on increasing compassion for others has also been shown to reduce stress-inducted inflammation (Pace et al., 2009). Finally, recent research found that self-esteem was a protective factor against increases in interleukin-1 receptor antagonist (IL-1Ra) and TNF-α following acute psychosocial stress, but self-esteem was unrelated to IL-6 (O’Donnell et al., 2008). Self-compassion is distinct from these related constructs in important ways. Although self-compassion may involve feelings of positive affect (i.e., compassion), these positive feelings are directed toward the self and toward the specific types of self-conscious emotions likely to arise in self-threatening situations, such as shame and humiliation (Dickerson et al., 2004). Self-compassion is also distinct from mindfulness. Whereas mindfulness involves non-judgmental observation of mental processes, self-compassion goes beyond non-judgment by involving the active expression of warmth and caring toward the self (Neff 2003a). Some research suggests that the development of self-compassion may in fact be a key mechanism explaining the effectiveness of mindfulness-based interventions (Baer, 2010). Finally, although self-compassion and self-esteem are both directed toward the self, they are conceptually and empirically distinct. Unlike self-esteem, self-compassion is non-evaluative: people can have compassion for themselves even if they are not feeling good about themselves. Self-compassion has been shown to predict more balanced emotional reactions to laboratory-based stressors compared to self-esteem, including lower levels of negative affect and more realistic self-appraisals, potentially because self-compassion is less likely than self-esteem to promote defensive self-enhancement as a means of coping with self-threat (Leary et al., 2007). Research has also shown that self-compassion is associated with greater self-worth stability (Neff and Vonk, 2009), lower narcissism (Neff, 2003b), and greater self-improvement motivation (Breines and Chen, 2012) compared to self-esteem, making it a potentially more adaptive strategy for coping with threats to the self. Recent research suggests that self-compassion may impact physical health through a number of pathways. For example, self-compassionate people may be more motivated to take care of their health by engaging in healthy lifestyle behaviors and adhering to medical regimens (Terry and Leary, 2011). Self-compassion may also affect health more directly by affecting the degree to which acute psychosocial stressors encountered in everyday life produce elevated levels of systemic inflammation that persist over time. In other words, self-compassion may operate through biological as well as health behavioral pathways. The goal of the current research was to examine the relationship between self-compassion and inflammatory responses to a repeated laboratory-based psychosocial stressor. The use of a repeated stressor was intended to provide a window into the types of physiological responses participants might be likely to experience in daily life when psychosocial stressors were encountered. A standardized laboratory-based stressor, the Trier Social Stress Test (TSST; Kirschbaum et al., 1993), was used to hold constant the type and degree of stress and to allow for repeated blood sampling and assessment of interleukin-6 (IL-6), a pro-inflammatory cytokine that has been shown to be sensitive to stress and also to predict long-term health outcomes (Brydon and Steptoe, 2005 and Steptoe et al., 2007). It was hypothesized that participants who were higher in trait self-compassion would show lower IL-6 responses to both an initial stressor and a similar stressor repeated on the following day. Furthermore, it was hypothesized that the relationship between self-compassion and IL-6 response would be independent of self-esteem and depressive symptoms, which have been linked to both self-compassion and inflammation in prior research (Hiles et al., 2012 and O’Donnell et al., 2008), and independent of demographic factors (i.e., age, gender, ethnicity), temporal factors (i.e., TSST start time), and body mass index (BMI). We also hypothesized that the relationship between self-compassion and inflammation would not be explained by differences in the extent to which the TSST was experienced as emotionally distressing.

Results 3.1. IL-6 response We first examined whether exposure to the TSST induced increases in circulating IL-6. Repeated measures ANOVA indicated that there was a significant effect of time for IL-6 on both day 1 and day 2, indicating that IL-6 levels increased significantly from baseline to 120 min following the TSST on both days: day 1 F (1, 39) = 43.64, p < 0.001; day 2 F (1, 34) = 49.01, p < 0.001. IL-6 increase did not differ significantly across days, F (1, 34) = 2.70, p = 0.11, indicating that while stress induced increases in plasma IL-6 concentrations, there was no habituation or sensitization upon repeated stress exposure, consistent with prior research ( von Kanel et al., 2006). Mean IL-6 levels across the 3 time points on both days are shown in Fig. 1. Mean IL-6 levels at baseline and 30 and 120min post-TSST on days 1 and 2. Fig. 1. Mean IL-6 levels at baseline and 30 and 120 min post-TSST on days 1 and 2. Figure options 3.2. Self-compassion and day 1 IL-6 response We next performed a linear regression analysis to examine whether self-compassion predicted IL-6 response on day 1. Consistent with hypotheses, self-compassion was a significant negative predictor of day 1 IL-6 response, β = −0.40, t (1, 36) = −2.61, p = 0.013, accounting for approximately 16% of the variance in IL-6 response, R2 = 0.16, F (1, 36) = 6.80, p = 0.013 (see Fig. 2 and Fig. 3). Self-compassion predicting IL-6 response. Fig. 2. Self-compassion predicting IL-6 response. Figure options Mean day 1 IL-6 levels at baseline and 30 and 120min post-TSST for participants ... Fig. 3. Mean day 1 IL-6 levels at baseline and 30 and 120 min post-TSST for participants above and below the mean on self-compassion (ns = 20 and 21 for the high and low self-compassion groups, respectively). Figure options 3.2.1. Covariate analyses We next examined the alternative hypothesis that the relationship between self-compassion and day 1 IL-6 response could be due to related psychological factors (i.e., self-esteem, depressive symptoms, post-TSST distress), or to demographic factors (i.e., age, gender, ethnicity), temporal factors (i.e., TSST timing), or physical factors (i.e., BMI). We first created a regression model where each covariate was entered simultaneously as a predictor of day 1 IL-6 response along with self-compassion. When all covariates were entered simultaneously, self-compassion remained a significant negative predictor of day 1 IL-6 response, β = −0.94, t(9, 28) = −3.31, p = 0.003. None of the covariates were significant predictors of day 1 IL-6 response (ps > 0.1), with the exception of BMI, which predicted marginally significant higher IL-6 response, β = 0.27, t(9, 28) = 1.72, p = 0.097. To ensure that the contribution of each covariate was not masked by the presence of other covariates in the model, we also conducted a series of linear regression models for which each covariate was entered independently, along with self-compassion. In each model, self-compassion remained a significant predictor of day 1 IL-6 response (ps < 0.05), and all other predictors were non-significant (ps > 0.1). 3.3. Self-compassion and day 2 IL-6 response We next examined whether self-compassion predicted IL-6 response on day 2. Unexpectedly, self-compassion was not a significant predictor of day 2 IL-6 response, β = 0.02, t(1, 32) = −0.08, p = 0.13, R2 = 0.001, F(1, 32) = 0.02, p = 0.88. The inclusion of covariates did not change this result. 3.3.1. Follow-up analyses Self-compassion was found to predict marginally significantly lower baseline IL-6 levels on day 2, β = −0.31, t(1, 33) = −1.95, p = 0.06, and this relationship was significant when controlling for baseline IL-6 levels on day 1, β = −0.25, t(1, 32) = −2.43, p = 0.02. Self-compassion did not predict baseline IL-6 levels on day 1, β = −0.15, t(1, 38) = −0.92, p = 0.36. Analyzed another way, self-compassion was a significant negative predictor of increase in IL-6 baseline levels from day 1 to day 2, β = −0.40, t(1, 33) = −2.49, p = 0.02, suggesting that participants lower in self-compassion were more likely to show greater IL-6 baseline levels on day 2 compared to day 1. This relationship remained significant when covariates were included (ps < 0.05), including day 2 TSST timing and day 2 post-TSST distress.