A Randomized Controlled Trial of Awareness Training Program (ATP), a Group-Based Mahayana Buddhist Intervention

This study evaluated the effectiveness of a Mahayana Buddhist teaching- and group-based intervention, the Awareness Training Program (ATP), which is textually aligned to a Mahayana Sūtra so that its theory and practice are coherent. The ATP aims to alleviate stress by enhancing participant’s compassion and wisdom of nonattachment. Middle-aged working adults (n = 122) in Hong Kong participated in this randomized waiting-list controlled trial. Self-reported psychological questionnaires were used to assess the participants’ level of stress (PSS), sense of coherence (SOC), psychological well-being (GHQ), and nonattachment (NAS) at pretest, posttest, and 3 months later. The data showed significant improvements in the intervention group over the controls for all outcome measures at posttest and 3 months later (post and post-3 PSS: ηp 2 = .15 and .16; post and post-3 SOC: ηp 2 = .05 and .10; post and post-3 GHQ: ηp 2 = .16 and .13; post and post-3 NAS: ηp 2 = .17 and .14). A mediation analysis demonstrated that nonattachment mediated both the treatment and the maintenance effects for all outcome variables (post and post-3 PSS: indirect effect ab = − 1.50 and − 1.70; post and post-3 SOC: ab = 2.48 and 3.61; post and post-3 GHQ: ab = − 1.65 and − 1.56; bootstrap 95% confidence interval (CI), CI does not include zero). The ATP may effectively reduce stress and improve a sense of coherence and psychological well-being by enhancing participants’ wisdom of nonattachment. This study provides promising evidence that the ATP could be an effective intervention for middle-aged working adults.

Over the past few decades, there has been increasing interest in incorporating Buddhist practices into group-based interventions for treating various psychological problems in the behavioral, social, and health sciences. The Buddhist practice of mindfulness has been incorporated into many of these groupbased interventions as a key component. Such practices are generally known as Bmindfulness-based interventions( MBIs). Scholars have demonstrated the efficacy and effectiveness of many of these MBIs in improving participants' psychological and physical health.
However, some scholars have shown that many MBIs vary in the type of mindfulness practice and in the manner that is incorporated into the interventions (Chiesa and Malinowski 2011;Singh et al. 2008;Van Gordon et al. 2015). Many scholars have also noted that one possible issue with these MBIs is that they may have applied mindfulness practice in an out-of-context manner (Bodhi 2011b;Shonin et al. 2013b;Singh et al. 2008) that Bdivorces it from its profoundly transformative potential^ (Kabat-Zinn 2015).
Another possible issue with these interventions is that they may have incorporated components from various Buddhist models of the elimination of suffering without considering if they are coherent. As Bodhi (2011a) has noted, there is a danger in creating Bcognitive dissonance^by merging theories and/or techniques from different schools and/or traditions. The reason for this argument is that each individual school and/or tradition has its own theoretical model and assumptions, which guide and dictate the development of the corresponding system of practice. Nevertheless, Shonin and Van Gordon (2015) have a different perspective on this discussion of lineages and traditions. They argued that Bthe Buddha wasn't concerned with endorsements or lineages, he was only interested in whether a meditation teacher had tamed their mind^ (Shonin and Van Gordon 2015, p. 143) and Blineage is a means of guiding people to enlightenment, but it is not enlightenment itself ( Shonin and Van Gordon 2015, p. 143). Therefore, it is argued that authentic Dharma lineages and traditions must be open to evolution and not become attached to whatever guiding principles they deem define them.
Despite these differing views, some scholars still believe that building an intervention that systematically incorporates a coherent Buddhist model of the elimination of suffering into its theoretical model and program content is a logical development given that many of these MBIs have been shown to be efficacious by incorporating only part of the Buddhist system of eliminating suffering (Sik 2010;Teasdale et al. 2003;Van Gordon et al. 2014). According to Van Gordon et al. (2015), these MBIs could be regarded as Bsecond-generation MBIs,â nd when compared to first-generation MBIs, such as Mindfulness-Based Stress Reduction (MBSR), these Bsecond-generation MBIs, such as Meditation Awareness Training (MAT), have integrated a greater range of meditation techniques and subscribe to a definition of mindfulness that is arguable to be more congruent with the traditional Buddhist construction^ (Van Gordon et al. 2016, p. 364).
This could be further developed by formulating an intervention that systematically combines a Buddhist theoretical model with a compatible meditation practice. Recent examples of second-generation MBIs include Mindfulness-Based Positive Behavior Support (Singh et al. 2013(Singh et al. , 2018 which includes the four immeasurables, compassion, attachment, and the five hindrances, and explicit teachings on Buddhist ethics, and Mindfulness-Based Symptom Management (Monteiro et al. 2018) which includes the Five Skilful Habits-the five lay Buddhist precepts-presented as ethical themes. However, current second-generation MBIs do not explicitly include Mahayana Buddhist teachings or groupbased interventions that adopt a textually aligned approach, and that has a coherent theory and praxis.
BMahayana Buddhist teaching,^Btextually aligned,^and Bcoherent theory and praxis^are important components to consider when formulating an MBI for the following reason: Mahayana Buddhism, unlike the more classical Theravada Buddhism that focuses on eliminating suffering, emphasizes the cultivation of compassion and wisdom to develop spiritual advancement, which will eventually lead to the attainment of Buddhahood. In a way, Mahayana Buddhism's emphasis of the cultivation of compassion and wisdom follows a Bwellness model,^whereas Theravada Buddhism's focus on the elimination of suffering is more consistent with a Bmedical model.T he importance of being Btextually aligned^concerns tracing back to the source of the teachings, thereby avoiding the potential danger of inconsistency between theory and praxis. There are thousands of sacred Buddhist texts that belong to many different schools and lineages, and each has its own emphasis and theoretical inclination. Further complicating the situation is that within both Theravada and Mahayana Buddhism, there are subschools and lineages that each has a unique theory and praxis. Therefore, to be Btextually alignedî s to ensure that the theory and praxis that are employed by Buddhist-inspired interventions are derived from text(s) that have a similar background in both theory and praxis and, as a result, avoid the possibility of creating Bcognitive dissonance.T he theoretical foundation of the newly developed Awareness Training Program (ATP) is rooted in the Mahayana Buddhist text of the Sandhinirmochana Sūtra (Keenan 2000), which is one of the most important texts of the Yogācāra tradition. The main philosophy of the Yogācāra tradition is the concept of Bconsciousness-only^or Bmind-only.^The tradition asserts that Bthe world as it appears to the unenlightened one is a mere representation of the consciousness^ (Kochumuttom 1999, p. 5), which is similar to Bseeing something by means of a clean mirror with the object before it, thinking one is seeing an image, and thinking there is a separate image apart from the object ( Cleary 1995, p. 45). As with other Buddhist schools, Yogācāra agrees that the source of human suffering is the result of Bontological addiction,^which refers to the unwillingness to relinquish one's attachment to an erroneous and deep-rooted belief in an inherently existing Bself^or BI,^along with the Bimpaired functionality^that arises from such a belief (Shonin et al. 2013a). The Sandhinirmochana Sūtra states that the cause of this delusion and attachment is that Bpeople add a conceptualized nature on top of the dependent nature and the real nature ( Cleary 1995, p. 30).
To help people overcome this delusion and attachment, the Sandhinirmochana Sūtra promises to expound a teaching that is Bcompletely explicit^and requires no interpretation to be understood (Willams 2004, p. 79). Instead of merely saying that all things are inherently empty to help people to let go of their ontological addiction to the concept of self, the Sūtra taught that on the one hand, all our phenomenological experiences can be explained and qualified by one of three types of characteristics (三自性); on the other hand, these three types of characteristics, when examined closely, will reveal three types of emptiness or essencelessness characteristics (三種無自性 性). These three types of characteristics are the following: (1) the characteristic of mere conceptual grasping (遍計所執 性) or the patterns that are entirely imagined or superficially established, for example, the name of a flower such as Brose^; (2) the characteristic of dependent origination (依他起性) or the patterns or forms that Bcome to be^depending on the coming together of other conditions, for example, a flower, which comes into being based on the coming together of its components such as petals, a stem and fragrance; and (3) the perfect characteristic of reality (圓成實性) or the full perfection characteristic that can be experienced by a fully enlightened person and of which such a person can be conscious, for example, the emptiness nature of a flower (Cleary 1995, pp. 23-24). The three types of emptiness or essencelessness characteristics are (1) the essencelessness of characteristics (相 無自性性), (2) the essencelessness of birth (生無自性性), and (3) ultimate essencelessness (勝義無自性性), which are, in a way, the other side of the coin of the three types of characteristics, namely, their intrinsic emptiness natures. For example, Brose,^a superficially established name, can carry much emotional value. However, when examined carefully, its ultimate characteristic is essencelessness, and it is intrinsically empty of essence because it is only a subjective concept that exists in a person's mind. Therefore, by understanding the three types of essencelessness characteristics or their intrinsic emptiness natures, a person can gain wisdom and insight to help him/her to forgo the attachment to all phenomenological experiences that would fall within the three types of characteristics and to therefore develop the wisdom of nonattachment.
To complement the teaching of the three types of characteristics and the three types of essencelessness characteristics, the Sandhinirmochana Sūtra also includes a corresponding meditation method. According to Cleary (1995, p. vii), one of the translators of the Sūtra, this meditation method Bwas the classical way, and many of the shortcomings and aberrations of modern Western meditation cults can be traced to abandonment of this tradition.Ŝ imilar to other traditional Buddhist schools, the Sandhinirmochana Sūtra divides the practice of meditation into two parts: tranquility (śamatha) and observation (vipaśyanā). The Buddha began the teaching of meditation in the Sūtra with a question from Maitreya, who asked based on what and dependent on what does a Mahayana practitioner practice meditation? The Buddha answered that it is based on the texts of the Mahayana teachings and is dependent on the commitment to attain perfect enlightenment (bodhicitta) (Keenan 2000, p. 51). The Sūtra delineates that to develop wisdom and eliminate delusion, it is necessary to follow the progressive pedagogical steps to develop wisdom, which are (1) wisdom realized by learning (śrutamayī prajñā) (聞所成 慧), (2) wisdom realized by thinking (cintāmayī prajñā) (思 所成慧), and (3) wisdom realized by practice (bhāvanāmayī prajñā) (修所成慧) (Keenan 2000, p. 63). These steps are also known as the Buddhist pedagogy of the three wisdoms or Bthe three kinds of knowing.P ractitioners who use this method of meditation focus on the teaching of the scriptures, and they gather and summarize them into a collective whole (for example, a poem or a mantra) to attentively contemplate them (Keenan 2000, p. 56). The ultimate aim of this practice is to enable the practitioner to see and fully understand that all the images and concepts upon which one has focused during either one's meditative practices or one's experiences in daily life are only images and concepts that are created by one's own consciousness, and ultimately, Bthere is nothing at all seeing anything at all^ (Cleary 1995, p. 45). By seeing the emptiness nature of phenomena or the three types of essencelessness, a practitioner will eventually eliminate delusion and attachment, which are the root causes of suffering. This is why we theorize that the development of wisdom in the form of nonattachment would be the key to the entire ATP, the mediating factor to facilitate the reduction of delusion, stress, and suffering. It was hypothesized that compared to the control group, the middle-aged working people who receive ATP would demonstrate significant improvements in the areas of stress reduction, stress management, psychological well-being and nonattachment and that these improvements could be maintained at a 3-month follow-up.

Participants
The participants were recruited through radio and universitywide promotion. The inclusion criteria for the participants include people (i) who are aged 30 to 60 years, (ii) who are working adults, (iii) who had achieved an educational level of upper secondary school or above, and (iv) who self-reported at least moderate distress with a score ≥ 4 (out of 7) in one of the following aspects: work, family, love affairs, interpersonal relationships, finances, health, or social environment. The exclusion criteria include people (i) who have been diagnosed with psychosis or mental illness, (ii) who are currently engaged in psychotherapy, and (iii) who have previously taken up intensive meditation training or practice. Participation in this study was on a voluntary basis and was not rewarded.
Seventy participants were required to detect a difference of means in a 2 × 3 mixed design analysis of variance (ANOVA) for a small effect size (d) of 0.4, an alpha of 0.05, and 80% power by using the Gpower software (http://www.gpower.hhu. de/) to conduct the statistical power analysis (Franz et al. 2007(Franz et al. , 2009). In addition, a 20% attrition rate was assumed. Thus, a total sample size of 88 participants would be required. Eventually, 122 participants were recruited and randomly assigned to either the ATP group or a waitlist control group. More participants were recruited than the calculated sample size because we also considered group-size efficiency, costs, and logistical arrangements. Both the intervention group and the control group completed the self-reported psychological questionnaires at baseline, post-intervention, and 3 months after intervention. The demographic and baseline characteristics of each allocation condition are presented in Table 1. The potential confounding variables were examined before the evaluation of the hypotheses. The results showed that the participants in the two groups did not differ in their demographic characteristics (i.e., gender, age, education level, marital status, and religious belief) and mean scores of the participants' level of stress (PSS) (t(120) = 1.39, p = .17), sense of coherence (SOC) (t(120) = − 0.53, p = .60), psychological well-being (GHQ) (t(120) = 0.36, p = .72), and nonattachment (NAS) (t(120) = − .90, p = .37) at baseline. By using two one-sided tests for equivalence (TOST; Rogers et al. 1993), the various psychological scores and age between these two groups were found to be equivalent at baseline (p < .05, the equivalence criterion was set at 20% of the ATP group's mean).

Procedure
The trial was conducted and reported according to the guidelines of the Consolidated Standards of Reporting Trials (CONSORT) 2010 (Moher et al. 2012;Schulz et al. 2010). The selection criteria were not disclosed to the participants to avoid the concealment of information. The screening was based on the information that the participants provided in the online registration form. If there was any missing or insufficient information that related to their eligibility, telephone or face-to-face interviews were arranged to acquire further information. All the participants who met the inclusion criteria were listed with an assigned number on an excel sheet. An independent and blind researcher, who was not part of this research project team, was provided with the assigned number only to perform the random selection by generating random numbers in a computer. Next, all the eligible participants were invited to attend a briefing session after the random selection. In both the briefing session and the recruitment process, the participants were informed that the ATP is a Buddhist teaching-based intervention that comprises Buddhist teachings and practice. During the briefing session, the research procedures and requirements for attending the ATP were introduced. The participants were told that they must commit to engaging in a daily meditation practice and attending the entire ATP. The participants then completed an informed consent form and questionnaire if they agreed to participate in the research. All answers were checked before the participants left the meeting to ensure that there were no missing data. After the completion of the baseline assessment, the group allocation was further processed by giving the participants' assigned numbers to the same independent researcher who performed the random selection. Because female participants were overrepresented, the participants were stratified by gender and assigned to either the intervention group or the control group by generating random numbers in the computer. The participants were blinded to their allocation condition until after the completion of the baseline assessment.

Intervention
As explained above, the theoretical foundation of the ATP is based on the teachings in the Mahayana Buddhist text, the Sandhinirmochana Sūtra. In the Sūtra, the Buddha declared that if a practitioner wishes to begin practicing meditation in the Mahayana tradition, his or her practice should be based on the texts of Mahayana teachings and depends on the commitment to attaining perfect enlightenment (bodhicitta) (Keenan 2000, p. 51). The texts of the Mahayana teachings serve as the foundation and guidelines for developing the wisdom of nonattachment. The commitment to attaining perfect enlightenment (bodhicitta) arises from the compassion to save all beings from suffering. Therefore, the primary objective of the ATP is to enhance the participants' wisdom of nonattachment and compassion. We posit that by enhancing these two qualities of the wisdom of nonattachment and compassion, the participants' stress management and psychological wellbeing will improve.
In the ATP, the development of both the wisdom of nonattachment and compassion follows the three pedagogical steps of developing wisdom, as taught in the Sandhinirmochana Sūtra. Under this pedagogical system, practitioners must first learn and memorize core Buddhist teachings to develop the wisdom of nonattachment that is realized by learning; next, they must repeatedly focus on and contemplate the meaning of these teachings to develop the wisdom of nonattachment that is realized by thinking. Finally, they must accordingly understand these teachings and practice to develop the wisdom of nonattachment that can be realized by practice (Keenan 2000, p. 63;Sik and Wu 2015).
The core Buddhist teaching that the participants learned and memorized in the ATP was the mantra BOṃ maṇi padme hūṃ,^and the meaning of the mantra is summarized as follows: The pearl of compassion is entirely auspicious, The wisdom lotus cannot be tainted, All phenomena arise interdependently and are therefore intrinsically nonarising, May all beings be able to realize these truths.
To develop compassion, the participants were first guided to see the universality of suffering for themselves and other people; then, they were guided to send compassionate wellwishes to themselves, other people and all sentient beings in succession. For the development of the wisdom of nonattachment and to overcome the Bontological addiction^or the attachment to the concept of Bself^or BI,^which are the sources of human suffering, the participants were guided to systematically study and recognize the emptiness or essencelessness characteristics of the three types of characteristics of phenomena to develop the wisdom of nonattachment. Lecture notes, revision exercises and corrections to the revision exercises were also incorporated into the program to help the participants to think and reflect on what they had learned in the workshops to develop the wisdom of nonattachment that can be realized by thinking. Finally, the participants gained insight into how concepts and attachment arise and cease through experiential activities, and they were taught to develop compassion and the wisdom of nonattachment through the meditative practice of tranquility (śamatha) and observation (vipaśyanā) to develop the wisdom of nonattachment that can be realized through practice.
The ATP consists of six 3-h workshops plus two whole-day weekend retreats (7 h, excluding the lunch hour; see Table 2). Each workshop began (except for the first session) with sessions of approximately 20 min of sharing to provide opportunities for the participants to share or ask any questions that related to their meditation experiences in the homework assignment. At the end of each workshop (except for the last session), revision exercises were done, corrections to the revision exercises were made and the weekly meditation homework assignment was given out. In addition, lectures, meditation practices, experiential and reflective learning activities and group discussions were employed to enrich the learning experience. Each participant received audio tracks with guided meditations, handouts, and homework assignment record worksheets to support their learning.
To maintain the consistency of the teaching of the program, HHS, the prime developer of the ATP, conducted all the workshops. HHS has more than 30 years of meditation experience. He is also the 45th generation lineage holder of Ling-ji (臨濟 宗) and the 10th generation lineage holder of the Gui-yang (溈 仰宗) Schools of Ch'an.

Measures
The 10-item Perceived Stress Scale (PSS-10; Cohen et al. 1983) was used to assess the participants' level of psychological stress. This scale measures the degree to which the situations in one's life are appraised as stressful (Cohen and Williamson 1988). The PSS-10 has 10 items and uses a 5point Likert scale that ranges from 0 (never) to 4 (very often). Lower scores indicate lower stress levels. In this sample, the Cronbach's alpha coefficient was .88 at baseline, .87 at posttest, and .89 at follow-up.
The 13-item Sense of Coherence Scale (SOC-13), which is also known as the Orientation to Life Questionnaire (OLQ-13), was used to measure the ability to cope with stress (SOC-13; Antonovsky 1987). According to Antonovsky (1987), a person with a strong sense of coherence can understand and manage life's difficulties and stress to stay well; such a person will perceive the world as coherent, predictable, comprehensible, and meaningful. Therefore, in this study, a sense of coherence is used to assess one's ability to manage stress. The SOC-13 consists of 13 items and uses a 7-point Likert scale that ranges from 1 to 7. Higher scores indicate a better ability to handle stress. The Cronbach's alpha coefficient was .87 at baseline, .90 at posttest, and .89 at follow-up in this study.
The 12-item General Health Questionnaire was used to assess the participants' psychological well-being (GHQ-12; Goldberg 1992). The GHQ-12 is widely used as a measure of general psychological health. It has 12 items and uses a 4point Likert scale that ranges from 0 to 3. Lower scores indicate better psychological well-being. In the present study, the internal consistency was very good, as shown by the Cronbach's alpha at .89 at baseline, .91 at posttest, and .90 at follow-up.
The Nonattachment Scale was used to measure the participants' level of wisdom in the form of nonattachment (NAS; Sahdra et al. 2010). This is a psychological measure of the Buddhist state or trait of nonattachment. The construct of nonattachment is characterized by having a subject quality of a relative absence of fixation on ideas, images, or sensory objects, and not feeling an internal pressure to get, hold, avoid, or change circumstances or experiences (Sahdra et al. 2010). It has 30 items and uses a 6-point Likert scale that ranges from 1 to 6. Higher scores indicate a higher level of nonattachment. The scale was translated into Chinese by using the back-translation method, and it has an excellent internal consistency, as shown by a Cronbach's alpha at .94 at baseline, .95 at posttest, and .96 at follow-up in this study.
A pop quiz was used at the 3-month follow-up to assess the knowledge proficiency of the Buddhist teachings and meditation methods that the participants had learned in the program. The participants of the intervention group were asked to answer 20 multiple-choice questions, and the participants who obtained ten or more correct answers were considered to have passed. The following are some of our sample questions: BWhat is the meaning of 'Oṃ'?^and BWhat are the obstacles that you encountered while meditating?^Moreover, the participants were also asked to indicate whether they have continued to practice meditation; if yes, they were asked about the frequency of their meditation practice and whether they had reviewed the content or handouts of the ATP within the 3 months after the intervention.

Data Analyses
The differences in the demographic characteristics across the groups at baseline were compared by conducting chi-squared tests for the categorical variables and independent sample t tests for the continuous variables with the Statistical Package for Social Sciences (SPSS Inc., Version 23.0, Chicago, USA) software. In addition, the equivalence of the psychological scores and age between groups at baseline were tested by conducting TOST using XLSTAT version 2018.3 (Btesting equivalence with TOST in excel tutorial,^2017).
Statistical analyses of the outcome measures were performed with SPSS version 23.0. Both an intention-to-treat (ITT) analysis and per-protocol (PP) analysis were performed to assess the robustness of the results. ITT was the primary analysis, and PP was the supporting analysis. For the ITT analysis, a conservative method was used that included all the participants once they were randomized, regardless of whether they had received the intervention (Armijo-Olivo et al. 2009, p. 40). A Little's Missing Completely At Random (MCAR) test was performed to assess whether the data were missing completely at random. The dropout data of the outcome variables at posttest and 3-month follow-up were addressed by multiple imputation. The total score for each individual participant's scale was calculated after each missing variable of the outcome measures was imputed. The pooled results of the F values, p values, and degrees of freedom of ANOVAs and analyses of covariance (ANCOVAs) were obtained by following the guidelines and procedures suggested by Van Ginkel (2014). For the PP analysis, listwise deletion was adopted to address the dropout data.
Both the ITT analysis and the PP analysis involved the following statistical analyses. A mixed betweenwithin subjects ANOVA was conducted to assess the effectiveness of the ATP on the participants' scores on each level of PSS, SOC, GHQ, and NAS across three between-group time points. Afterwards, the intervention effect (a comparison of the differences between the pretest and posttest scores) and maintenance effect (a comparison of the differences between the pretest and post-3month follow-up scores) were examined. The intervention effect and maintenance effect were examined by performing a two-way mixed ANOVA to compare the interaction effect between groups and among times on each of the outcome measures. For any significant interaction that was found, an ANCOVA was conducted to examine the group effect after adjusting the baseline. The pooled effect size of the imputed data set of the ANOVAs and ANCOVAs were manually calculated by following the rules suggested by Harel (2009). All effects were deemed to be significant when the p value fell below the .05 significance level (two-tailed).

Attrition and Attendance
The number of dropouts in this study was 12 (10%) of which 7 and 5 were from the intervention group and the control group, respectively. Three participants from the intervention group and 2 participants from the control group immediately dropped out after receiving the notification of their allocated ATP schedule because they were not available during the allocated timeslot. Other reasons for dropping out include a loss of interest in participating in the research, a busy work schedule, illness, a loss of contact, and a conflict between work and program schedules, although the participant wanted to continue to participate (see Fig. 1). Of the participants who attended the ATP, more than 90% (91.2%) attended at least seven out of eight sessions (of which six were 3-h workshops and two were all-day retreats).

Analysis of the Self-Reported Outcome Measures
Regarding the dropout data, a nonsignificant Little's MCAR test, χ 2 = 302.424 (df = 392, p = 1), indicated that the data were missing completely at random (Little 1988). Twenty imputed data sets were produced for data analysis and for pooling the results of the ITT analysis. The results of the ITT (n = 122) and PP analyses (n = 110) are summarized in Table 3. The results showed that there were statistically significant improvements across the three between-group time points in all outcome variables for the ATP group over the controls, with an overall medium effect size in SOC, a medium to large effect size in PSS, GHQ, and NAS.
Nearly all of the participants (98.1%) from the intervention group passed the pop quiz at the post-3-month follow-up. Forty-one (75.9%) of the 54 participants have continued to Excluded (n=298) Did not meet inclusion criteria (n=254) Unavailability to participate the whole or part of ATP (n=11) Unavailable to come to the briefing session and baseline assessment (n=4) Lost contact (n=2) Declined to participate in the research(n=1) Did not include because the optimal group size and target sample size were met (n= 26) Withdrew (  .20 ATP Awareness Training Program, WL waitlist control, Pre pre-intervention, Post post-intervention, Follow-up post 3-month follow-up, PSS Perceived Stress Scale, SOC Orientation to Life, GHQ General Health Questionnaire, NAS Nonattachment Scale Means sharing the same numerical superscript are significantly different across time at the .05 level. Means sharing the same letter superscripts are significantly different across group at the .05 level. *p < .05, **p < .01, ***p < .001, two-tailed. The degrees of freedom for the F statistic are PSS = 2, 231.89; SOC = 2, 237.10; GHQ = 2, 235.94; NAS = 2, 237.38 for the analyses on the intention-to-treat sample and 2, 216 for the per-protocol sample practice meditation, and 27 (50%) have reviewed the content or handouts of the ATP within the post-follow-up period. More than one fifth (20.8%) of them meditated every day, and more than two thirds (63%) of them maintained the practice of weekly meditation within the post-follow-up period.

Mediation Analysis
We hypothesized that wisdom in the form of nonattachment would be the mediating factor of the outcome measures. Specifically, the intervention group's level of NAS mediated the effect of the ATP on PSS, SOC, and GHQ. Therefore, we examined the mediator of the ATP, i.e., the changes in NAS, for each outcome variable at posttest and at 3-month followup after controlling for their respective baseline levels by using the four-step approach proposed by Baron and Kenny (1986). The four steps that are essential to establish mediation are as follows: the first step is to illustrate that the causal variable (i.e., the intervention) is correlated with the outcome variable (i.e., the post-PSS, post-SOC, post-GHQ, post-3 PSS, post-3 SOC, and post-GHQ scores); the second step is to show that the causal variable is correlated with the mediator (in this study, i.e., the changes in the pre-post NAS scores and the changes in the pre-post-3 NAS scores); the third step is to demonstrate that the mediator affects the outcome variable while controlling for the causal variable; and the fourth step is to establish that the mediator mediates the relationship between the causal variable and the outcome variable, and the effect of the causal variable on the outcome variable that controls for the mediator should become nonsignificant or less significant (Baron and Kenny 1986;Kenny 2016). A series of hierarchical linear regression analyses were conducted. In addition, the bootstrapping method (Hayes 2018a) was also performed as an alternate method to support the results. Bootstrapping was run with the PROCESS macro v3.0 by Andrew F. Hayes (2018b) in SPSS Inc., Version 25.0, Chicago, USA. The bootstrap was based on 5000 bootstrap samples with a bias-corrected accelerated method to estimate the 95% confidence interval (CI). If zero is not included within the estimated CI, it indicates a significant mediation effect at the 0.05 level.

The Mediating Effect of Nonattachment at Posttest and at Post-3-Month Follow-Up
The following is a description of the hierarchical linear regression analyses of the mediating effect of nonattachment at posttest. First, the participants of the ATP group were observed to have significant changes in the outcome variable at posttest, after accounting for the baseline levels of the outcome variable (post-PSS: B = − 2.99, p < .001; post-SOC: B = 4.59, p = .004; post-GHQ: B = − 4.52, p < .001). Second, the analyses indicated that the participants of the ATP group increased their levels of nonattachment from baseline to posttest (B = 18.16, p < .001). Third, the changes in the levels of nonattachment from baseline to posttest were found to be a significant predictor of the post-outcome variable after accounting for the baseline levels of the outcome variable and intervention (post-PSS: B = − 0.092, p < .001; post-SOC: B = 0.14, p = .007; post-GHQ: B = − 0.094, p < .001). Finally, we regressed the post-outcome variable on the baseline levels of the outcome variable in the first block and experimental condition, and the pre-post changes in the levels of nonattachment were included as predictors in the second block. For the PSS outcome variable, we observed that the previously significant effect of the ATP on lower levels of PSS at posttest became less significant (B = − 1.49, p = .018), while the pre-post changes in the levels of nonattachment continued to be a significant predictor (B = − 0.090, p < .001). For the SOC outcome variable, we observed that the previously significant effect of the ATP on increasing the levels of SOC at posttest became nonsignificant (B = 2.11, p = .24), while the pre-post changes in the levels of nonattachment continued to be a significant predictor (B = 0.14, p = .006). For the GHQ outcome variable, we observed that the previously significant effect of the ATP on lower levels of GHQ at posttest became less significant (B = − 2.87, p = .001), while the pre-post changes in the levels of nonattachment continued to be a significant predictor (B = − 0.095, p < .001). The results of the hierarchical linear regression analyses showed that the conditions that are required to establish mediation between the mediator and the respective outcome measure were met (Fig. 2). For the mediating effect of nonattachment at the post-3 follow-up, the results of the hierarchical linear regression analyses were similar to the results at posttest, which also demonstrated that the conditions that are required to establish mediation between the mediator and the respective outcome measure were met (Fig. 2). Therefore, NAS was a mediator of the treatment effects and maintenance of the treatment effects across all outcome measures (PSS, SOC, and GHQ) at posttest and 3month follow-up. Bootstrapping, which is another popular method for mediation analysis, was also conducted. The bootstrap results showed that NAS significantly mediated the relationship between the ATP and all outcome measures (see Fig. 2), which supports the findings of the hierarchical linear regression analyses. In addition, the results of Sobel's test were also consistent with the results of the above analyses.

Discussion
We assessed the effectiveness of the ATP, a semisecularized group-based intervention based on the Mahayana Buddhist teaching that is Btextually aligned^with Bcoherent theory and praxis.^By employing lectures, experiential and reflective learning activities, meditation homework assignments, group discussions, and revision exercises, the ATP has been demonstrated to be effective in improving stress levels, a sense of coherence, psychological well-being, and the wisdom of nonattachment for middle-aged working adults, and the therapeutic improvements were maintained at 3-month follow-up. The outcomes were aligned with the hypothesis, and the experimental group demonstrated significant improvements over the control group on all the self-reported outcome measures.
Our findings are generally consistent with the previous studies of various forms of MBIs that show significant improvement in the levels of stress reduction, stress management and psychological well-being in working adults (Foureur et al. 2013;Shonin et al. 2014;Taylor et al. 2016;Wallmark et al. 2013) and middle-aged adults (Lee and Bang 2010). In general, the effect sizes of the interaction effect between group and time on each of the outcome measures were from medium to strong. The between-group effect size and within-group effect size in this study are also generally consistent with the findings of a recent meta-analysis of MBI studies in reducing the psychological distress of working adults (Virgili 2015).
The data from our study indicated that wisdom in the form of nonattachment (NAS) served as the key component of ATP to mediate the improvement of the levels of perceived stress (PSS), sense of coherence (SOC), and psychological wellbeing (GHQ). This supported our hypothesis that wisdom in the form of nonattachment is an important and effective mediator to reduce an individual's delusions and suffering. These findings endorse Sahdra's assertion (Sahdra et al. 2010, p. 125) that Brelease from mental fixation (nonattachment) is thought to encourage more objective perception, greater compassion, reduced selfishness, and release from, or letting go of, what Buddhist call 'afflictive' emotion, thus alleviating suffering.Â significant maintenance effect was also found at 3-month follow-up. We attribute this significant maintenance effect of the ATP to the effectiveness of the three pedagogical steps of developing the wisdom of nonattachment as taught in the Fig. 2 Mediation diagrams that summarize the hierarchical linear regression and bootstrap analyses by using nonattachment as a mediator of the effect of the intervention on stress, sense of coherence, and psychological well-being. ATP Awareness Training Program, PSS Perceived Stress Scale, SOC Orientation to Life, GHQ General Health Questionnaire, NAS Nonattachment Scale, BS results of bootstrap analyses, HLR results of hierarchical linear regression analyses; *p < .05, **p < .01, ***p < .001. If zero is not included within the estimated confidence interval, it indicates a significant mediation effect at the 0.05 level. Numbers in parentheses are the B after controlling for the mediator. Numbers in square brackets are the lower level confidence interval and upper level confidence interval