Effectiveness of Zhong‐Yong thinking based dialectical behavior therapy group skills training versus supportive group therapy for lowering suicidal risks in Chinese young adults: A randomized controlled trial with a 6‐month follow‐up

Abstract Background Dialectical behavior therapy (DBT) is a first‐line treatment for the prevention of suicide. Zhong‐Yong thinking could be viewed as a Chinese way of dialectical thinking, has long been a culturally dictating thinking style in China. To enhance cultural adaptability, we integrated Zhong‐Yong thinking into DBT group skills training and examined its efficacy in suicidal prevention compared with a supportive group therapy and a wait‐list group in high‐risk suicidal Chinese college students. Methods A total of 97 suicidal participants were randomized to either Zhong‐Yong thinking based DBT group skills training (DBTZYT, n = 33), or supportive group therapy (SGT; n = 32), or wait‐list group (WL; n = 32). DBTZYT was a 12‐week program based on Zhong‐Yong thinking instead of dialectical thinking, coaching participants mindfulness, emotion regulation, distress tolerance, and interpersonal effectiveness. Supportive group therapy was a 12‐week program aiming at improving interpersonal effectiveness and emotion regulation skills. Outcome measures were assessed at pre‐ and post‐treatment and 6‐month follow‐up. Results At post‐treatment measures, the levels of suicidal ideation, hopelessness, psychache symptoms, and general psychopathology had significantly decreased in both intervention groups; at the 6‐month follow‐up measures, the intervention effects were better maintained in the DBTZYT group rather than in the SGT group. Specifically, DBTZYT was more effective in relieving participants’ long‐term obsessive‐compulsive, anxiety, hostility, phobic, psychotic, and additional symptoms. Conclusions Zhong‐Yong thinking not only could integrate with DBT skills training in Chinese young adult population, but also has special strength in enhancing DBT’s efficacy.


| INTRODUC TI ON
Suicide is the second leading cause of death in young adults aged 15-29 years (WHO, 2017). The lifetime and 12-month prevalence of suicidal thoughts and behaviors worldwide is 7.2% and 1.9% among college entrants (Mortier et al., 2018). There is 2.8% prevalence of suicide attempts and more than 600,000 suicide attempters among college students in China, indicating that more attention should be paid to this population (Yang, Zhang, Sun, Sun, & Ye, 2015).
DBT was initially developed for the treatment of borderline personality disorder, it is efficacy has received extensive empirical support in recent years (Bass, Van Nevel, & Swart, 2014;Linehan et al., 2006Linehan et al., , 2015Mcmain & Links, 2009;Panos et al., 2014). DBT is recognized as a firstline treatment for the prevention of suicidal behavior in diverse clinical populations, including high-risk and acutely suicidal clients (DeCou, Comtois, & Landes, 2018;Lin et al., 2019). The standard DBT includes individual psychotherapy, group skills training, telephone coaching, and a therapist consultation team. Among the shorter and less intensive versions of DBT, group skills training has received more attention and empirical supports (Gibson, Booth, Davenport, Keogh, & Owens, 2014;Krantz, Mcmain, & Kuo, 2018;Soler et al., 2009). The DBT group skills training incorporates almost all the important elements in the full DBT program, including mindfulness, emotion regulation, distress tolerance, and interpersonal effectiveness skills (Linehan, 1993).
The theoretical basis of DBT originates from dialectical thinking, which emphasizes that reality is comprised of two opposing forces or positions and intends to pursue a balance between two extremes and bring them together (Lynch, Chapman, Rosenthal, Kuo, & Linehan, 2010). Dialectical thinking is thus a process whereby apparent contradictions are able to be synthesized to provide a broader understanding of the "truth" in a situation. It seems that dialectical thinking should be easily accepted by easterners (Miyamoto & Ryff, 2011), given that Zhong-Yong thinking has long been a culturally dictating thinking style in China, and some researchers argued that Zhong-Yong thinking could be viewed as a Chinese way of dialectical thinking (Chiu, 2000;Liu, Wang, & Yang, 2015;Nisbett, Peng, Choi, & Norenzayan, 2001). However, DBT's application in China is limited.
Specifically, apart from a few literatures that introduce the practice of DBT, research investigating the treatment effects of DBT using randomized controlled trials in China is scarce. Therefore, we wonder that whether the effect of DBT intervention would be equivalent or superior to other widely-used interventions in Chinese suicidal young adults? Is it necessary to consider cultural adaptability when applying DBT intervention to Chinese population?
Recent studies demonstrate that Zhong-Yong (middle-way) thinking still has indispensable influence on Chinese people's mental health (Yang et al., 2016) and behavioral performance (Pan & Sun, 2017;Yao, Yang, Dong, & Wang, 2010). Zhong-Yong thinking, as the most representative eastern philosophy, derives from Confucianism, emphasizes the virtue of pursuing the middle ground and never going to extremes (Yang, 2009). Zhong-Yong thinking is acknowledged as a metacognitive process, characterized by acting appropriately and flexibly under different situations. It has a profound influence on shaping Chinese people' perception and cognition (Chang & Yang, 2014;Chiu, 2000;Guo, Li, Huang, & Chen, 2017;Kim, Yang, & Hwang, 2006;Wu & Lin, 2005). Theoretically, both dialectical and Zhong-Yong thinking advocate tolerance of contradiction, avoiding going to extremes, and overcoming dichotomous, rigid patterns of thinking. In practice, these two thinking styles were both found to be beneficial for regulating extreme emotional distress (Miyamoto & Ryff, 2011;Yang et al., 2016). Therefore, it might be plausible to incorporate Zhong-Yong thinking into DBT treatment of Chinese suicidal young adults. Moreover, compared with dialectical thinking, the concept of Zhong-Yong thinking is more easily accepted and understood by Chinese people; and the connotation of Zhong-Yong thinking is more compatible with the cognitive style of the Chinese.
In the present study, we combined DBT group skills training with Zhong-Yong thinking as the underlying philosophy to improve its cultural adaptability. Making such modification to the well-established DBT practice among an eastern population whose thinking style is different from their western counterparts (Xinyue, Lingnan, Qing, Junpeng, & Baumeister, 2012) would further enhance the understanding of whether and how a psychological intervention could apply to individuals in different cultural contexts. In particular, the purposes of the present study were to explore whether DBT could integrate with Zhong-Yong thinking in Chinese young adults with high-suicidal risks, and to test whether Zhong-Yong thinking based DBT would demonstrate superior or equivalent or inferior efficacy compared with supportive group therapy and wait-list group.

| Study design and participants
We conducted a three-arm randomized nonclinical controlled trial.
We offered two interventions without fee: Zhong-Yong thinking based DBT (DBT ZYT ) group skills training and supportive group therapy (SGT), comparing the outcome measures with a wait-list (WL) group. The length of treatment was relatively brief (12 weeks instead of the standard DBT skills training of 16 weeks), because participants showed less severe suicidal risks compared with clinical suicidal According to the SBQ-R score, 258 students were identified as in heightened suicidal risks. We contacted them via telephone and invited them to participate in a structured diagnostic interview using MINI-International Neuropsychiatric Interview (MINI) (Sheehan et al., 1998) Chinese version (Si et al., 2009). A total of 244 students attended the interview and received diagnoses from certified psychiatric doctors. We screened the 244 students for eligibility using the following exclusion criteria: (a) severe depression requiring immediate pharmaceutical treatment, and/or received a major depressive disorder diagnosis with Self-Rating Depression Scale (SDS) standard score ≥ 70; (b) diagnosed with bipolar disorder; (c) showed psychotic symptoms; (d) severely cognitively impaired; (e) currently received psychotropic or psychological intervention; (f) drug abusing; (g) other conditions that required immediate hospitalization and/or pharmaceutical treatment, such as acute suicidal attempt or severe self-harming behaviors.
A total of 189 eligible students were obtained and further invited to participate in the current suicide prevention program. A total of 97 students agreed to participate and signed the informed consent (see Figure 1). The average age of the participants was 19.20 ± 0.75 years, ranged from 17 to 21 years. 42 (43.3%) of them were male.

| Measures
The Suicidal Behaviors Questionnaire revised (SBQ-R) Chinese version assessed suicide behaviors and ideation (Osman et al., 2001) and functioned as the screening tool of suicidal risks. SBQ-R has 4 items, each tapping a different dimension of suicidality. Item 1 taps into lifetime suicide ideation and/or suicide attempt. Item 2 assesses the frequency of suicidal ideation over the past 12 months. Item 3 assesses the threat of suicide attempt. Item 4 evaluates self-reported likelihood of suicide behavior in the future. When item 1 score ≥ 2, and/or SBQ-R total score ≥ 7, indicate heightened suicidal risks. The reliability and validity of the scale have been extensively verified in both English (Osman et al., 2001) and Chinese population (Zhao, Zhao, Xiao, Yang, & Zhang, 2013). Beck Hopelessness Scale (BHS) Chinese version was used as another indicator of suicidal risk. BHS contains 20 items and three subscales: feelings about the future, loss of motivation, and expectations (Beck, Weissman, Lester, & Trexler, 1988).
The reliability and validity of the Chinese version have been proven to be acceptable (Xiao, 2012). During the study period, the frequency of suicidal attempts and hospitalization due to suicidal attempts (0 = no, 1 = yes), as well as the use of psychotropic drugs (0 = no, 1 = yes) were recorded as complements to the outcome measures.

| Intervention
We developed a 12-week Zhong-Yong thinking based DBT group skills training program according to the dialectical behavior therapy with Suicidal Adolescents Manual for DBT skills training group (Linehan, 1993;Miller, Rathus, & Linehan, 2007), as well as other related literatures (Gibson et al., 2014;Soler et al., 2009). The project leader  Table 1). Two modules are acceptance-oriented skills: mindfulness (2 weeks) and distress tolerance (3 weeks); two modules are change-oriented skills: emotional regulation (4 weeks) and interpersonal effectiveness (3 weeks). Mindfulness was taught in the first two sessions and integrated throughout the whole sessions; (c) the program replaces the concept of dialectical thinking with Zhong-Yong thinking, by using approachable language to illustrate the overarching principles of Zhong-Yong thinking. We coached participants to develop a middle-way (Zhong-Yong) attitude to deal with their daily dilemmas, and to learn the wisdom of "maintaining the best balance between extremes." We used Zhong-Yong thinking principle to illustrate the mindfulness skills. In the distress tolerance module, we presented some prominent historical figures such as Yuanzhang Zhu and Bei Liu as role models to show how to use the doctrine of Zhong-Yong to accept and adapt to the harsh reality without making it worse. In the emotional regulation module, we coached participants using Zhong-Yong thinking to reevaluate the situation that might elicit extreme emotions. In the interpersonal effectiveness module, we taught participants using Zhong-Yong thinking to cope with interpersonal conflicts, finding the middle ground in opposing perspectives. The group sizes were 7-10 members, with an average of 8 members per group. The sessions lasted 2 hr per week, lasting for 12 consecutive weeks. The therapists were one doctor-level psychologist (a licensed professional) as the primary group leader and two graduate students as the secondary group facilitators. They were all trained previously on DBT skills. The two graduate students received DBT supervision from the doctor-level psychologist during the study. The doctor-level psychologist was also responsible for the adherence to treatment manuals.
We also developed a 12-week supportive group therapy based on the theory, research, and therapeutic practice of interpersonal psychology (Horowitz & Strack, 2012). The goal was to improve self-regulation in a safe, supportive interpersonal context. Therefore, the program included two treatment modules that were integrated in the whole sessions: emotional regulation and interpersonal effectiveness, and one telephone-coaching module ( Table 1). The group sizes, schedule, as well as the length of therapy, were the same as DBT ZYT group. The group leaders included two therapists: one doctor-level psychologist and one graduate student, and they were all skilled in group psychotherapy. The doctor-level psychologist was responsible for the supervision and adherence to the treatment protocol during the study.

| Procedure
After enrollment, participants were randomized in blocks of three to either DBT ZYT or SGT or WL group by a computer program. Upon assignment, all participants were instructed by the research assistant to complete the outcome measures and a demographic questionnaire. Throughout the study, the research assistant was blind to study hypotheses and participants' assignments. DBT ZYT and SGT groups would receive a 12-week intervention, respectively.
WL group received no special intervention during this period. After 12 weeks, all participants received postintervention assessments and a gift. Participants in DBT ZYT and SGT groups were interviewed on their views and feelings about the intervention program. They were also asked to indicate on a 1-10 scale to what extent they found the program was helpful (1 = not at all helpful, 10 = very helpful), and were encouraged to continue to practice the skills in their daily life. To maintain and enhance the effectiveness of the intervention, during the 6-month follow-up period, the therapist-team continually called participants of DBT ZYT and SGT groups once a month to provide individual telephone coaching. Six months later, participants in intervention groups were contacted again and received the follow-up assessments and another gift. WL group did not attend the follow-up assessments.
To enhance the ecological validity, during the intervention and follow-up period, we allowed all participants to receive non-DBT individual psychotherapy voluntarily or psychiatric services as deemed appropriate by the psychiatrist. They were also encouraged to call a 24/7 hot line when crisis arises. All the psycho-medical intervention would be recorded as covariate variables. For intervention groups, treatment attendance was also recorded. Dropout was defined as "missing more than 3 consecutive sessions or missing a total of 4 sessions." For all the 3 groups, failing to attend the post-treatment and/or follow-up reassessments was considered dropout.

| Statistical analyses
Outcome analyses were based on the intent-to-treatment (ITT) model, that is, the missing data were imputed using the last observation carried forward method. This method assumes that missing values are missing completely at random, and participant's responses are basically stable from the point of dropout to trial completion, rather than declining or improving further (Molnar, Hutton, & Fergusson, 2008 ANOVAs to reveal the overall intervention effects. We also conducted a series of 2 (group: DBT ZYT , SGT) by 3 (time: PRE, POST, F/U) mixed factorial ANOVAs to compare the short-term and longterm intervention effects of DBT ZYT and SGT groups. If the assumption of sphericity has not been met, the Greenhouse-Geisser correction would be applied. Paired-sample t tests were conducted to examine changes in the outcome measures from pre-to post and to follow-up measures. The multiple paired t tests with a Bonferroni correction were used to keep the Type I error at 5% overall. To measure the magnitude of differences between groups, we reported Hedges's g or partial η 2 as effect size indicators.

| Treatment attendance and descriptive data
As shown in Figure 1, at the post-treatment assessments, five par-  Inspection of the data suggested that the distribution of all questionnaire scores were within the accepted range of ±2 skewness and kurtosis for parametric analyses (Gravetter & Wallnau, 2014). The outcome data are presented in Table 2. One-way ANOVA and independent-sample t test showed that all the baseline assessments did not significantly differ among groups. The suicidal risk measures of the WL group at pre-and post-treatment did not show significant changes. Although most outcome measures in the two intervention groups showed improvements, the group differences in post-treatment and follow-up did not reach statistical significance. As repeated measures ANOVA could control for factors that cause variability between subjects, it is more powerful to detect changes in mean scores over three time points between groups, we reported outcome analyses using repeated measures ANOVA and paired-sample t test. As the assumptions of "missing at random" and "the participant's responses remaining basically stable from the point of dropout to trial completion" were not seriously violated, we would use "last observation carried forward" method to handle missing values.

| Outcome analyses at post-treatment measures
As shown in Table 3 Table 4). Most effect sizes were comparable between the DBT ZYT and SGT groups, and the SGT group showed slightly larger effect sizes for the INT, HOS, and PHOB subscales (the differences of Hedges'g > 0.08).

| Outcome analyses at follow-up measures
Since only the two intervention groups were assessed at followup, we conducted separate 2 (group: DBT ZYT , SGT) by 3 (time: PRE, POST, F/U) repeated measures ANOVAs for four outcome measures to detect the group differences across the three time points.
As shown in Table 3 ( Paired-sample t tests indicated that in the DBT ZYT group all the outcome measures did not significantly change from POST to F/U. In the SGT group, however, the BHS, PAS, and SCL-90-R average score significantly increased from POST to F/U. To further explore the differential effects of the two interventions programs on psychopathological symptoms, we conducted separate 2 (group: DBT ZYT , SGT) by 3 (time: PRE, POST, F/U) repeated measures ANOVAs for ten subscales of SCL-90-R (Table 4 in gray shading). There were significant main effects of time in all ten subscales. The interaction effects of time by group were not TA B L E 2 Outcome descriptive data and difference tests for intent-to-treat sample (M ± SD)

Outcomes DBT ZYT (n = 33) SGT (n = 32) WL (n = 32) F (2, 94) or t (63)
Sig. As for the OC, ANX, HOS, PHOB, PSY, and ADD subscales, the effects of time by group interaction were significant. Paired-sample t tests revealed that in the DBT ZYT group, the improvement of obsessive compulsive, anxiety, hostility, phobic, psychotic, and additional symptoms remained stable or even enhanced from POST to F/U.

SBQ-
However, in the SGT group, the above-mentioned subscale scores significantly increased from POST to F/U.

| D ISCUSS I ON
In the present study, we found that the two intervention groups evidenced more reductions in suicidal risks at post-treatment measures compared with the wait-list group. Specifically, at post-treatment, the levels of suicidal ideation, hopelessness, psychache symptoms, and general psychopathology significantly decreased in both intervention groups. More importantly, the changes observed during intervention were better maintained in the DBT ZYT group rather than in the SGT group. In another word, the short-term treatment efficacy was basically comparable between the two intervention groups, but Zhong-Yong thinking based DBT group skills training demonstrated superior efficacy compared with supportive group therapy in the long term. In particular, the two interventions had similar effects on participants' short-and long-term somatization, depressive, and paranoid ideation symptoms. However, DBT ZYT was more effective in improving participants' long-term obsessive compulsive, anxiety, hostility, phobic, psychotic, and additional symptoms; while supportive group therapy showed slightly superior efficacy in improving participants' short-term interpersonal sensitivity, hostility, and phobic symptoms. We speculate that reductions in psychopathological symptoms as measured by SCL-90-R may be critical for the longterm maintenance of reduction in suicidal behaviors. Therefore, these findings provided empirical evidence for designing the most suitable psycho-behavioral intervention programs for different subgroups of high-risk suicidal young adults with diverse psychopathological profiles and cultural backgrounds.
As both intervention programs showed significant short-term effectiveness in reducing suicidal ideation, hopelessness, psychache, and psychopathological symptoms, some nonspecific factors (e.g., social support, therapeutic alliance, and the structure of treatment) may contribute to the treatment effects. However, in the following section, we will focus our discussion on the differences in long-term efficacy between the two interventions to reveal the mechanisms by which psycho-behavioral interventions might work in suicide prevention programs.
Previous studies demonstrated that compared with older adults, young adults often experienced more intense psychological distress (Brummer, Stopa, & Bucks, 2014) and greater emotion regulation difficulties (Orgeta, 2009). These can lead to impulsive emotional responses, such as suicidal ideation and attempts.
Studies have shown that DBT skills training could address the four main areas in which youth typically have problems: difficulty of managing emotions, confusion about self, impulsive behaviors, and interpersonal problems in school setting (Mazza et al., 2016). Compared to SGT, DBT skills training is more structured and places more emphasis on psychoeducation, skills training, and the active role of the therapist (Soler et al., 2009). Previous studies demonstrated that skills training is an essential element in suicide prevention programs in view of the emotion regulation Abbreviations: ADD, additional items subscale average score; ANX, anxiety subscale average score; BHS, Beck Hopelessness Scale total score; DBT ZYT , Zhong-Yong thinking based dialectical behavior therapy group skills training; DEP, depression subscale average score; F/U, 6-month follow-up assessment; HOS, hostility subscale average score; INT, interpersonal sensitivity subscale average score; OC, obsessive-compulsive subscale average score; PAR, paranoid ideation subscale average score; PAS, Psychache Scale total score; PHOB, phobic subscale average score; POST, post-treatment assessment; PRE, pretreatment assessment; PSY, psychoticism subscale average score; SBQ-R, Suicidal Behaviors Questionnaire revised total score; SCL-90-R, Symptom Checklist-90-revised total average score; SGT, supportive group therapy; SOM, somatization subscale average score; WL, wait list.  deficit prominent in suicidal young adults (Robinson, Hetrick, & Martin, 2011 to dialectical thinking, Zhong-Yong thinking discourages "blackor-white" and "all-or-nothing" thinking, and promotes holistic thinking (Yang et al., 2016). Zhong-Yong thinking also advocates accepting different perspectives from others, seeking harmony and consistency, not simply compromising between opposite perspectives (Wu & Lin, 2005). These thinking styles are beneficial for coping with interpersonal conflicts, finding the middle ground in opposite perspectives and facilitating interpersonal effectiveness. The interview revealed that DEARMAN skill was difficult to learn for those depressed young adults. In the first half of the DBT ZYT program, they were hard to keep an assertive, confident, eye-contacted position when they expressed a need and tended to be too apologetic or confrontational when they declined someone's request. However, in the later stage of the program, most participants in the DBT ZYT group gradually learned how to find a middle-wayed manner to express their need or to decline unreasonable requests. We thus conclude that in a population traditionally dictated by Confucian culture, Zhong-Yong thinking not only could integrate with standardized DBT skills training, but also has special strength in enhancing DBT's efficacy.
The current study has some notable strengths. For example, we recruited a subclinical sample with a per group sample size large enough to detect a reliable effect; we used a rigorous randomized, controlled design with a supportive group and wait-list group to test the efficacy of DBT ZYT ; we conducted 6-month follow-up measures in the two intervention groups to examine their long-term effects.
There were also several limitations should be noted, which temper the conclusions could be made and also recommend directions for future study. First, the sample was heterogeneous with diverse diagnoses and some of the participants did not meet any mental disorder diagnosis, leading to the limit that the conclusion may be difficult to generalize to a wider population. Second, only the research assistant who administered the outcome measures was blind to study hypotheses and participants' assignments, it was difficult to keep the participants as well as the therapists blind to study hypotheses, therefore, we are unable to rule out the possible placebo effect from the true intervention efficacy. Third, the wait-list group did not receive the 6-month follow-up assessment, there might be a natural rate of improvement due to possible assessment reactivity. Fourth, we have failed to provide adherence ratings for either treatment groups. Thus, we cannot definitively state that the treatment was in strict compliance with the manuals. The last limitation was related to the reliance on self-report outcomes, which may attenuate the validity of causal conclusions due to social desirability effect, inadequate introspective ability, and other response biases. Future studies could use more rigorous double-blind design to verify the conclusions in a wider population, including clinical and subclinical populations, and at the meantime combine self-report outcomes with other information, such as behavior or physiological data. Using multi-modal assessments could provide a more global and accurate picture of the participants.
To conclude, compared to supportive group therapy, Zhong-Yong thinking based dialectical behavior therapy demonstrated comparable short-term efficacy in reducing Chinese college students' suicidal risks; at the 6-month follow-up, the therapeutic gains were better maintained in the DBT ZYT group rather than in the SGT group. Zhong-Yong thinking not only could integrate with DBT skills training in a Chinese young adult population, but also has special strength in enhancing DBT's efficacy.

CO N FLI C T O F I NTE R E S T
The authors declare no potential conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are openly available