The benefits of being mindful: Trait mindfulness predicts less stress reactivity to suppression

Highlights

• We trained 48 healthy males to suppress their emotions during an acute stressor.

• Heart rate reactivity and subjective anxiety were monitored during CO₂ inhalation.

• Trait mindfulness predicted the effects of suppression on the stress response.

• Trait mindfulness may buffer against effects of maladaptive emotion regulation strategies.

Abstract

Background and objectives

There has been a recent proliferation of research evaluating the efficacy of mindfulness as a clinical intervention. However, there is still little known about trait mindfulness, or how trait mindfulness interacts with maladaptive emotion regulation strategies. The current study further explores the effect of trait mindfulness on emotion regulation, as well as whether specific factors of trait mindfulness are uniquely associated with subjective and autonomic reactivity to stress.

Methods

Forty-eight healthy male participants were trained in the use of the suppression strategy and then instructed to suppress their responses to the inhalation of a 15% CO₂-enriched air mixture for 90 s while their subjective distress and heart rate were recorded.

Results

After controlling for anxiety-related variables, the ability to provide descriptions of observed experiences predicted less heart rate reactivity to CO₂ inhalation, while skillfulness at restricting attention to the present moment was uniquely predictive of less subjective distress. The tendency to attend to bodily or sensory stimuli predicted greater distress during CO₂ inhalation.

Limitations

The inclusion of only healthy males limits the generalizability of study findings. Also, the sample size was relatively small.

Conclusions

These findings suggest that factors associated with trait mindfulness predict less stress reactivity and distress while engaging in suppression above and beyond other variables that have been shown to predict anxious responding. The implications for emotion and clinical research are discussed.

Introduction

The ability to successfully exert control over emotional experiences is a fundamental skill in humans that promotes interpersonal functioning, positive affect, and overall well-being. Individuals differ in their habitual use of emotion regulation strategies, and these differences are associated with specific behavioral, affective, and interpersonal outcomes (Gross and John, 2003, John and Gross, 2004). Maladaptive emotion regulation strategies are associated with psychopathology, greater psychological distress, poorer quality of life, stress-related symptoms, and negative affect (Aldao et al., 2010, Amstadter, 2008, Hofmann et al., 2012, Moore et al., 2008).

Research in emotion regulation has recently begun to explore the role of mindfulness as an important factor that might positively influence the stress response and emotion regulation more generally. Mindfulness is a state of consciousness originating in Eastern philosophies and religion that focuses on the practice of directing one's attention to the present moment while adopting a nonjudgmental perspective toward experiences (Kabat-Zinn, 1990). Mindfulness possesses both state- and trait-like characteristics, the former of which is particularly responsive to practice or meditation (Bishop et al., 2004, Brown and Ryan, 2004, Carmody and Baer, 2008). Studies have failed to demonstrate a linear relationship between state- and trait-like characteristics of mindfulness (Thompson & Waltz, 2007), suggesting separate but related constructs.

The construct of trait mindfulness has been theorized to consist of multiple skills or facets, and this factor structure has been empirically validated in multiple studies (Baer et al., 2004, Baer et al., 2006, Christopher et al., 2012). The factors include the ability to observe and attend to experiences, the ability to describe those experiences, the ability to focus attention on the present moment, and the ability to adopt a kind, nonjudgmental attitude toward experiences (Baer et al., 2004). Trait mindfulness has been associated with positive mental health outcomes, including life satisfaction, self-esteem, and optimism (Brown & Ryan, 2003). It has also demonstrated negative correlations with symptoms of depression, anxiety, and stress-related symptoms (Cash & Whittingham, 2010), neuroticism (Giluk, 2009), difficulties in emotion regulation (Baer et al., 2006, Coffey et al., 2010), cognitive reactivity (Raes, Dewulf, Van Heeringen, & Williams, 2009), and experiential avoidance (Baer et al., 2004).

A limitation of prior studies of trait mindfulness is the use of measures designed to assess only one facet of mindfulness, namely present-moment awareness (e.g., Brown and Ryan, 2003, Chadwick et al., 2008), which precludes the exploration of which factors of trait mindfulness are most important in predicting outcomes. These distinct facets of trait mindfulness have demonstrated differential predictive validity across a variety of outcomes, including eating pathology (Adams et al., 2012), substance use (Eisenlohr-Moul, Walsh, Charnigo, Lynam, & Baer, 2012), and symptoms of depression and anxiety in both clinical (Desrosiers, Klemanski, & Nolen-Hoeksema, 2013) and non-clinical samples (Cash & Whittingham, 2010). For example, Desrosiers et al. (2013) found that the ability to describe internal and external experiences was inversely related to anxious arousal in adults presenting for treatment at a mood and anxiety disorders clinic, but the ability to notice and attend to these experiences was positively related to anxious arousal.

Much of the research to date on mindfulness consists of correlational research between trait mindfulness and psychological health, mindfulness-based clinical interventions, and laboratory research on the immediate effects of mindfulness induction exercises on stress and emotion regulation (for a review, see Keng, Smoski, & Robins, 2011). Despite the promising results of mindfulness-based interventions (e.g., Hofmann et al., 2010, Khoury et al., 2013) and brief mindfulness induction exercises (e.g., Arch and Craske, 2006, Broderick, 2005), there has been little research conducted on the effects of trait or dispositional mindfulness beyond correlational research. Exceptions include Arch and Craske (2010), who found that trait mindfulness predicted less reactivity to a hyperventilation task in both anxious and non-anxious individuals. In another study of undergraduate students, trait mindfulness was found to predict lower cortisol responses and less subjective distress to a social evaluative threat (Brown, Weinstein, & Creswell, 2012). To our knowledge, there have been no studies to date exploring the effect of trait mindfulness on anxious responding during a more vigorous laboratory stressor, or while monitoring both subjective distress and autonomic reactivity.

One advantage of laboratory studies is that they allow for more control than clinical interventions or correlational studies, and as a result, are especially useful in the elucidation of causal relationships. Biological challenge paradigms, such as carbon dioxide (CO₂) inhalation, are frequently used in the study of anxiety, psychological risk factors for anxiety, and emotion regulation strategies (Amstadter, 2008, Cisler et al., 2010). Another methodological benefit of using biological challenge paradigms to study emotion regulation and related factors is that substantial research has been conducted on other variables that are predictive of anxious responding to CO₂ inhalation (e.g., anxiety sensitivity, fear of suffocation, trait anxiety, and distress tolerance), and these individual difference variables can then be included as covariates in regression models to allow for a more precise analysis of the relationships between predictor and dependent variables.

One of the most extensively studied forms of emotion regulation during biological challenges is suppression (i.e., attempting to prevent or inhibit the expression of an emotional experience or uncomfortable physical sensations), which tends to produce increased physiological arousal, greater autonomic instability, and more stress-related symptoms, despite the desire to down-regulate arousal (Campbell-Sills, Barlow, Brown, & Hofmann, 2006). Research exploring the effect of expressive suppression on physical pain suggests that suppression results in delayed recovery from pain and decreased pain tolerance, as well increased subjective reports of distress and pain intensity (Cioffi and Holloway, 1993, Masedo and Rosa Esteve, 2007, Moore et al., 2008). Indeed, individual differences observed in the duration of stress reactivity or cardiovascular recovery from a negative event have been linked to differences in an individual's ability to effectively regulate his or her emotions (Fredrickson et al., 2000, Tugade and Fredrickson, 2004). Reliance on suppression to cope with emotional distress is also associated with greater vulnerability for both the development of emotional disorders and the persistence of symptoms (Amstadter, 2008). However, prior studies utilizing laboratory stressors to explore factors contributing to emotion regulation have traditionally focused only on anxiety-related variables. As a result, little is known about factors that may promote adaptive emotion regulation or buffer against the negative effects of less effective emotion regulation strategies.

The purpose of the current study was to study the relationship between trait mindfulness and stress reactivity to instructions to suppress distress during CO₂ inhalation. In order to explore the unique contribution of the four factors of trait mindfulness, we controlled for anxiety-related variables that have demonstrated strong predictive validity for anxious responding in previous biological challenge paradigms using suppression. We chose suppression as an emotion regulation strategy for three key reasons. First, we wanted to control for individual differences in the habitual use of emotion regulation strategies since in the absence of explicit instruction on how to handle distress and uncomfortable physical sensations during the challenge, it is likely that participants would utilize a variety of strategies and introduce unnecessary confounds. Secondly, the effects of suppression on anxious responding during CO₂ challenges (i.e., elevated physiological arousal) are very well documented (e.g., Campbell-Sills et al., 2006, Feldner et al., 2003, Feldner, Zvolensky, et al., 2006, Karekla et al., 2004, Levitt et al., 2004, Spira et al., 2004). Lastly, suppression is an emotion regulation strategy acutely associated with negative affect, greater psychological distress, and slower recovery from pain (e.g., Aldao et al., 2010, Amstadter, 2008, Cioffi and Holloway, 1993, Moore et al., 2008) and has been shown to contribute to the onset and maintenance of emotional disorders (e.g., Amstadter, 2008). Therefore, evaluating the effects of trait mindfulness during a suppression manipulation is a more robust test of whether trait mindfulness protects or buffers against the negative consequences of maladaptive emotion regulation strategies.

We hypothesized that trait mindfulness would predict the subjective effects of the suppression instructions, such that participants higher in trait mindfulness would report less distress during inhalation of a 15% CO₂-enriched air mixture. Given the lack of prior research on how trait mindfulness influences autonomic responses to stress, our assessment of heart rate reactivity, as well as whether specific factors of trait mindfulness demonstrated differential relationships with stress reactivity, was exploratory in nature.