Depression is one of the most common mental health problems among youth 1. This can be attributed, in part, to the critical and vulnerable period of cognitive development they undergo 2,3. Intervening in youth depression is critical from a cognitive perspective. Mindfulness, as the third wave of the cognitive revolution 4, presents a promising approach to address the risk factors associated with depression 5. A comprehensive understanding of the mechanisms and mediators underlying the relationship between mindfulness and depression in youth is necessary to inform the development of targeted interventions.
Mindfulness refers to the intentional redirection of attention to the present moment and the adoption of a non-judgmental attitude 6. As Monitor and Acceptance Theory (MAT) posits, the core mechanisms of mindfulness and mindfulness training are awareness and acceptance. Awareness involves clear recognition of one's internal experiences and the process of disengaging from distractions, whereas acceptance entails a non-judgmental, truthful, allowing, and friendly attitude toward present-moment experiences 7. Specifically, awareness refers to reducing efforts to control internal states, including reducing the suppression of negative evaluative thoughts and negative emotions, indicating that awareness is related to the concepts of thought suppression and emotion suppression 8–11. Further, acceptance involves increasing the acceptance of present-moment experiences, reflecting a positive self-attitude akin to the concept of self-esteem 6,7.
Therefore, the reduction of suppression and the enhancement of self-esteem may be particularly important in understanding the positive effects of mindfulness on depression. To date, no study exploring mindfulness and depression has simultaneously examined the factors derived from the two aspects of MAT, as well as the two facets of suppression (i.e., thought suppression and emotion suppression). Thus, this study aims to explore the potential mediating roles of thought suppression, emotion suppression, and self-esteem in the relationship between mindfulness and depression and further compare the differential effects of various sub-dimensions of mindfulness among youth.
Mindfulness and Suppression
Suppression can be divided into thought suppression and emotion suppression. Thought suppression, initially proposed by Wegner et al. through the White Bear Experiment 12, refers to the intentional avoidance of thinking about certain things, particularly those that elicit unpleasant emotions 13. Thought suppression can temporarily alleviate negative emotions, and many techniques in cognitive therapy aim to train individuals to regulate their negative thoughts 14,15. However, thought suppression typically fails to effectively regulate negative emotions and cognition 16. Research indicates that thought suppression can lead to an immediate enhancement effect 17,18 and a rebound effect 19–22. The former refers to increased attention and processing of the target thought during suppression, and the latter refers to the inability to suppress the target thought after the suppression period, resulting in a stronger re-emergence of the target thought in consciousness. Studies have shown that individuals experiencing prolonged suppression and the subsequent failure of suppression may develop increasing levels of stress, leading to psychopathological states including depression 23.
Emotion suppression refers to the conscious control of negative emotions 24. Emotion suppression involves not only the inhibition of emotional expression but also subjective experience, physiological arousal, and emotional behavior, ultimately reflecting the inhibition of the entire emotional response system 25. Emotion suppression can undermine cognitive abilities 26 and result in more intense negative psychological experiences 27, adverse physiological responses 28, and psychological maladjustment 29. Several studies have found a significant positive correlation between emotion suppression and depression 30,31.
Mindfulness may be an effective method for improving thought suppression and emotion suppression. According to the theoretical foundation of Mindfulness-Based Cognitive Therapy, mindfulness cultivates a decentered perspective on thoughts and emotions 32. In this decentered perspective, various thoughts or emotions are mere fleeting mental events rather than accurate reflections of reality or truth, and they do not require specific behavioral responses from the individual. This concept is similar to the mechanism of reperceiving proposed by Shapiro, which suggests that mindfulness involves disengaging from consciousness and perceiving one’s present-moment experiences more objectively and clearly 33. The decentered, or reperceiving, perspective is believed to directly lead to a reduction in rumination, as individuals can observe their thoughts without succumbing to detailed, analytical thinking patterns 34,35. This study suggests that the same mechanism could also lead to a reduction in thought suppression and emotion suppression because individuals can objectively observe their thoughts without engaging in intentional concealing or inhibition.
In contrast to suppression, exposure to thoughts or emotions is one of the elements of mindfulness. When exposed to negative feelings or cognitions, individuals become desensitized to them, thus leading to a reduction in their emotional reactions and avoidance behaviors, which is similar to Exposure Therapy 36,37. Shapiro also proposed exposure as a sub-mechanism of mindfulness 33. One study showed that self-reported mindfulness levels were negatively correlated with experiential avoidance and thought suppression in a non-meditating sample 38. Further research indicated that experienced meditators had lower levels of thought suppression and fear of emotions compared to non-meditating groups 39. Another study also showed a significant negative correlation between mindfulness and emotional suppression 40.
Therefore, thought suppression and emotion suppression may be important mediating variables in the effect of mindfulness on depression. Additionally, as thought suppression is more related to cognition and emotion suppression is more related to emotion, these two variables may have different mediating effects in the process of mindfulness. This study will simultaneously examine and compare thought suppression and emotion suppression, which may improve the understanding of the effects of mindfulness on both cognitive and emotional dimensions.
Mindfulness and Self-Esteem
Self-esteem is the overall attitude of an individual toward their self-worth 41. Numerous studies have shown a strong correlation between low self-esteem and depression 42–46. According to Beck's Cognitive Theory of depression, negative self-evaluation is a significant manifestation of depression 14,47. Depressive Attribution Theory 48,49 and Vulnerability-Stress Theory 50 also posit a close relationship between low self-esteem and depression. In contrast to the scar model, which assumes that depressive symptoms leave scars in individuals that result in lower self-esteem 51,52, the vulnerability model 14,53 suggests that low self-esteem is a risk factor for the development of depression. This model has been supported by the majority of research 54–58. Individuals with low self-esteem often lack positive feelings toward themselves and hold negative self-perceptions, which stem from a general attitude that "I am worthless and insignificant in this world" 59. Higher levels of self-esteem have been associated with less severe depression, reduced suicidal tendencies, and indirect effects on suicidal ideation 60.
An increasing body of research indicates that mindfulness has a positive impact on self-esteem. A systematic review incorporating 32 studies showed that the 15 cross-sectional studies suggested a significant positive correlation between mindfulness and self-esteem, and most intervention studies demonstrated that mindfulness-based interventions significantly increased self-esteem 61. Regarding different dimensions of mindfulness, researchers have found the strongest correlation between the acceptance dimension of mindfulness and self-esteem 62–64. However, no significant correlation was found between the observing dimension of mindfulness and self-esteem 65,66. To verify the results of previous studies, this study not only examined the mediating effect of self-esteem but also further explored the relationship between self-esteem and different facets of mindfulness.
Suppression and Self-Esteem
Thought suppression and emotion suppression may play a role in the relationship between mindfulness and self-esteem. Inhibiting negative thoughts about oneself can have detrimental effects on self-esteem. Multiple experimental studies have shown that inhibiting negative self-referential thoughts is significantly associated with low self-esteem 67. Compared to the control group, participants in the thought-suppressing group experienced a lower state of self-esteem, as well as more anxiety and depressive emotions 68–70. Further, the negative impact of thought suppression has been shown to extend beyond short-term laboratory studies. For individuals with unstable self-esteem, lower levels of self-esteem are associated with stronger thought suppression and intrusive thinking 70.
Suppressing emotions also has negative effects on self-esteem. Research has demonstrated that when individuals suppress their emotions, they experience more internal distress, such as increased depressive emotions, fatigue, lower self-esteem, and lower life satisfaction 72. The regulatory strategy of emotion suppression was also found to significantly predict self-esteem 73. Therefore, this study proposes that there may be two mediated chains between mindfulness and depression: cognitive inhibition and self-esteem, and emotional inhibition and self-esteem.
Current Study
This study aimed to explore the possible psychological mechanisms between mindfulness and depression in youth by investigating the mediating effects of thought suppression, emotion suppression, and self-esteem. Based on existing theoretical perspectives, we constructed a chain mediation model to test the following hypotheses (Fig. 1): H1, mindfulness would be negatively related to depression; H2, thought suppression would mediate the relationship between mindfulness and depression; H3, emotion suppression would mediate the relationship between mindfulness and depression; H4, self-esteem would mediate the relationship between mindfulness and depression; H5, thought suppression and self-esteem would be sequential mediators in the relationship between mindfulness and depression; and H6, emotion suppression and self-esteem would be sequential mediators in the relationship between mindfulness and depression. We also examined the effect of these mediators on the relationship between the five mindfulness facets and depression.