Background
Mindfulness-based intervention has gained increased attention in mental health research. Jon Kabat-Zinn [
1], who developed mindfulness-based stress reduction (MBSR), defined mindfulness as “the awareness that emerges through paying attention on purpose, in the present moment, and nonjudgmentally to the unfolding of experience moment by moment” [
2]. Two standard mindfulness approaches exist: MBSR and mindfulness-based cognitive therapy (MBCT) [
3]. Both have been developed as 8-week programs where practitioners observe their sensations, emotions, and thoughts with a non-reactive attitude. These programs have been shown by many studies to be effective for a wide variety of psychological problems, including depression and anxiety [
4].
However, few studies have been used to assess the effects of mindfulness group therapy based on a standard 8-week program for depression and/or anxiety in Japan. Yanagisawa, Fujita, Mizuno, Adachi, Yoshino, and Takazawa [
5] conducted a rare practical study that monitored a group program based on MBCT for Japanese psychiatric hospital outpatients who had been diagnosed with depression, anxiety disorders, fibromyalgia, and schizophrenia. Yanagisawa et al. [
5] found a significant decrease in depression and a significant increase of quality of life in their single-arm study. However, they did not monitor changes in anxiety or show the results of follow-up (FU) assessment. Therefore, in this study we aimed to evaluate the possible effects of an 8-week mindfulness group therapy program for depression and anxiety until a 2-month FU. It will necessary to further clarify the changes in depression and anxiety through the mindfulness program in future randomized controlled trials.
The mechanisms of action for 8-week mindfulness programs have been studied, and many candidates for mediator variables have been proposed. Recent systematic reviews [
6,
7] have presented multiple studies showing that increased mindfulness and reduced negative repetitive thinking mediate improved clinical outcomes. However, those mediation models did not show complete mediation; that is, those mediators explained only a part of variance in clinical outcomes. Therefore, we aimed to explore other possible mediators that have thus far lacked sufficient investigation. We focused on three cognitive, emotional, and behavioral tendencies as process variables: mind wandering, self-compassion, and behavioral inhibition and behavioral activation systems (BIS/BAS).
First, we considered that mindfulness group therapy programs may decrease mind wandering, which in turn leads to decreased depression and anxiety. Mind wandering has been described as “drifting away from a task toward unrelated inner thoughts, fantasies, feelings, and other musings” [
8]. Several studies have shown that mind wandering is related to depression [
9], reduced psychological health [
10], and reduced levels of happiness [
11]. In a study by Mrazek, Smallwood, and Schooler [
12], self-reported mindfulness was negatively correlated with mind wandering, and mindfulness meditation reduced mind wandering in an experimental setting. In addition, mind wandering was found to mediate the relationship between self-reported mindfulness and negative moods in a cross-sectional study [
13]. Thus, mind wandering is thought to be a mediating variable for improvement in depression and anxiety through mindfulness group therapy. However, this has not yet been examined.
Additionally, it was considered that mindfulness group therapy programs may increase self-compassion, in turn leading to decreased depression and anxiety. Neff [
14] described self-compassion as “being touched by and open to one’s own suffering, not avoiding or disconnecting from it, generating the desire to alleviate one’s suffering and to heal oneself with kindness.” It was found that self-compassion is related to reduced depression, trait anxiety, and greater life satisfaction [
14]. It has also been shown that the effects of MBCT on recurrent depression are mediated by enhancements in self-compassion and mindfulness [
15]. However, few studies have shown an effect of mediation through self-compassion for the reduction of depression and anxiety in 8-week mindfulness group therapy, according to recent systematic reviews [
6,
7].
In addition, we considered that mindfulness-based group therapy programs may decrease BIS and increase BAS, leading to decreased depression and anxiety. The BIS is an aversive motivational system that is sensitive to signals of punishment, nonreward, and novelty. It inhibits behaviors that may lead to negative or painful outcomes, and this inhibits movement toward goals [
16]. The BIS is related to trait anxiety [
17] and depression [
18]. The BAS is an appetitive motivational system that is sensitive to signals of reward, nonpunishment, and escape from punishment [
16]. The BAS is related to positive affectivity [
16] and lowered levels of depression [
18]. Some factors of mindfulness are related to lower BIS and higher BAS [
19]. Thus, decreases in the BIS and increases in the BAS are thought to mediate the changes in depression and anxiety brought about by mindfulness group therapy programs, but this has not yet been examined.
The present study tested the following hypotheses: As a result of taking part in a mindfulness program, 1) depression and anxiety will decrease (outcome variables), and such decreases will last for at least 2 months FU; 2) mindfulness, self-compassion, and the BAS will show increases, while mind wandering and the BIS will show decreases (process variables), and these changes last for at least 2 months FU; and 3) changes in outcome and process variables will be correlated, and we will explore the correlations between them.
Discussion
This study investigated three hypotheses: After doing the program, participants’ 1) depression and anxiety scores will decrease (outcome variables) and these decreases will last at least until the 2-month FU; 2) mindfulness, self-compassion, and the BAS scores will increase, and mind wandering and the BIS scores will decrease (process variables), and the changes will last at least up to the 2-month FU; and 3) changes in outcome and process variables will correlate. For hypothesis 3, we examined correlations of depression and anxiety to each process variable.
Depression and anxiety scores significantly decreased from pre- to post-intervention, with moderate to large effect sizes. Those decreases were sustained at least up to the 2-month FU. Therefore, hypothesis 1 was supported. These results are consistent with the results of meta-analysis studies, which have shown positive effects from mindfulness-meditation programs for depression and anxiety at post-intervention and FU [
30,
31]. Furthermore, anxiety significantly decreased from post-intervention to FU in the current study. It may be that learning mindfulness through the application of mindfulness for daily situations and voluntary meditation practices (17.9 ± 18.2 meditation hours over the 2 months post-intervention) after the program might decrease anxiety even further. The results showed that this 8-week mindfulness program was effective for people suffering from depression and anxiety in Japan. Further study is needed to compare such a mindfulness-based program with a control intervention.
As far as the process variables were concerned, only the total scores for FFMQ, observing, and nonreactivity were increased from pre- to post-intervention with increases sustained until FU. Therefore, hypothesis 2 is only supported in regard to some aspects of mindfulness. However, nonjudging was increased from pre-intervention to FU and post to FU. Thus, it is possible that the practice of mindfulness through daily application or formal practice after the program could contribute to delayed improvement. This is consistent with further improvements in trait anxiety from post-intervention to FU. However, describing, acting with awareness, and mindfulness as measured by MAAS, which included overlapping items with acting with awareness, unexpectedly did not increase. Acting with awareness did not significantly increase in similar studies of 8-week mindfulness programs in Japan [
5,
32]. It is possible that the Japanese response style to acting with awareness and MAAS, which inquire as to the degree one’s own awareness of one’s current state, is distinct from that of other cultural populations. However, the results for describing are inconsistent with those of another study in Japan, where describing significantly increased before and after a mindfulness-based program [
5]. The results may depend on the variant characteristics of the participants, instructors, and also on the content of the program. The describing scores (pre-intervention, 23.3 ± 4.5; post-intervention, 24.9 ± 5.9) in our sample were higher than those (pre-intervention, 19.3 ± 6.2; post-intervention, 21.2 ± 5.6) obtained by Yanagisawa et al. [
5]. Further, the participants were more varied in Yanagisawa et al. [
5], whose study included people who were, for example, diagnosed with schizophrenia, fibromyalgia, or hypochondria. Therefore, it is possible that our participants evinced relatively fewer problems with regard to the skill of describing their own experiences did than the previous study. With regard to the content of the program, Yanagisawa et al. [
5] conducted some role plays and experience sharing about how to deal with thoughts and emotion in addition to following the MBCT manual [
3]. Also, the average number of participants was 4.7 per course, which amounted to relatively fewer people and provided participants with more opportunities to describe and to report their experience in a session. Those differences may have affected the differences in the changes recorded in the describing scores between our study and Yanagisawa et al. [
5].
Self-compassion increased from pre-intervention to FU but not from pre- to post-intervention. This is inconsistent with Bergen-Cico and Cheon [
33], who showed that self-compassion significantly increased through mindfulness-based intervention for full-time and part-time students in the USA. However, Ito, Sasara, Kuriyama, Kikai, Hiranaka, Tamae, and Sakamoto [
32] did not find a significant increase in self-compassion through mindfulness-based intervention for professional palliative caregivers in Japan. Although the samples for those studies differ from those of the current study, it may be that Japanese participants have difficulty learning self-compassion through a mindfulness-based intervention, at least as assessed soon after the program. Despite the delay in the effect, the increase from pre-intervention to FU is in line with the finding that demonstrated an increase in self-compassion from the pre-intervention stage to 1-month after the MBCT for recurrent depression [
15].
Furthermore, mind wandering was not significantly changed. It may be that mind wandering is distinct from negative repetitive thinking in its perseveration. Negative repetitive thinking like rumination and worry have shown mediator effects in 8-week mindfulness programs [
6,
7]. It may be more important to decrease the perseverative aspects of thinking in 8-week mindfulness programs. To determine this, measurement of mind wandering and perseverative thinking must be conducted concurrently, and the mediating effects must be compared.
For the BIS/BAS, there were no significant changes. Changing such an aspect of temperament as the BIS/BAS may be difficult in an 8-week program. Furthermore, BAS activity is said to cause beginning (or increasing) movement toward goals. This is seemingly inconsistent with the “being mode,” which does not drive an individual to capture something, as taught in mindfulness programs. The BAS scale may not discriminate positive feelings directed by mindfulness from hedonic feelings related to the “doing mode.”
Improved nonreactivity was correlated with decreased depression and anxiety from pre- to post-intervention, as predicted in hypothesis 3. Furthermore, improved nonjudgment was also correlated with decreased depression and anxiety from pre-intervention to FU. Nonreactivity and nonjudging belong with the acceptance component in Monitor and Acceptance Theory [
34], a recently proposed model to describe mechanisms of mindfulness for cognition, affect, stress, and health. Our results showed that the acceptance component is important for effects on depression and anxiety as a common mechanistic variable. In FFMQ, nonreactivity includes positive items, while nonjudging has only reversed items. It is possible that nonreactivity was actively trained within the 8-week program, while arising judgment reduced in delayed timing. Thus, nonreactivity is effective for symptoms within the program period, while nonjudging might be effective in the period that includes FU. Describing was specifically correlated with trait anxiety. It might be an important factor for people who have anxiety to notice their experiences and express them in particular.
Self-compassion had a relatively large correlation with depression and anxiety as a whole. This is consistent with studies showing a mediating effect for self-compassion in the effects of MBCT on recurrent depression [
15]. It is interesting that the only positive factor for SCS is correlated with depression from pre- to post-intervention, even though the negative factor for SCS includes some items that are similar to depressive symptoms, for example, a sense of isolation. These results imply that self-compassion is closely related to depression and anxiety and that it has a high potential to improve those symptoms.
Finally, decreased BIS was correlated with improved anxiety and depression (only from pre-intervention to FU). The BIS may cause avoidance, which is a primary target of mindfulness-based intervention. BIS items include covert avoidance, which might be attenuated by mindfulness intervention. In sum, hypothesis 3 is supported regarding some aspects of mindfulness, self-compassion, and the BIS.