The impact of mindfulness on suicidal behavior: a systematic review

Abstract Introduction Mindfulness-based interventions (MBI) have been growing progressively as treatment options in the field of mental health. Aim: To assess the impact of mindfulness-based interventions for reducing suicidal thoughts and behaviors. Methods A systematic review was performed in December 2020 using PubMed, PsycINFO, EMBASE, SciELO, Pepsic, and LILACS databases with no year restrictions. The search strategy included the terms (‘mindfulness’ OR ‘mindfulness-based’) AND (‘suicide’ OR ‘suicidal’ OR ‘suicide risk’ OR ‘suicide attempt’ OR ‘suicide ideation’ OR ‘suicide behavior’). The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO), CRD42020219514. Results A total of 14 studies met all inclusion criteria and were included in this review. Most of the studies presented Mindfulness-Based Cognitive Therapy as the MBI assessed (n=10). An emerging and rapidly growing literature on MBI presents promising results in reduction of suicide risk, particularly in patients with MDD. Four studies assessing other MBI treatment protocols (Mindfulness-Based Stress Reduction; Daily Mindfulness Meditation Practice; Mind Body Awareness and Mindfulness-Based Cognitive Behavior Therapy) all demonstrated that MBI reduces factors associated with suicide risk. Conclusion MBI might target specific processes and contribute to suicide risk reduction.


Introduction
Mindfulness is conceptualized as a particular way of paying attention to the present moment in an intentional, non-judgmental, and non-reactive manner. 1 Mindfulness-based interventions (MBI) have been growing progressively as treatment options in the field of mental health. 2 Mindfulness-based Cognitive Therapy (MBCT), 3 Mindfulness-Based Stress Reduction (MBSR), 4 and Mindfulness-Based Relapse Prevention (MBPR) are of particular note among the most well-known MBI. 5 Different MBI approaches have proven effective in the treatment of psychiatric disorders 6 (e.g., anxiety, depressive, personality disorders) 7,8 and are associated with improved outcomes of other clinical conditions (e.g., cancer, rheumatoid arthritis). 9,10 MBSR was introduced to the field of medicine by John Kabat Zinn and was initially developed to help people manage pain and chronic conditions for which clinicians could no longer offer help. 4 The 8-week protocol guides participants through specific meditation and movement practices to cultivate mindfulness. 4 Since its inception, in addition to chronic pain, it has been shown to be effective in a wide variety of medical http Suicidal thoughts and behaviors are important public health concerns around the world, 11 although the prevalence appears to be higher in lower-middleincome countries such as Brazil. 12 In this context, it is imperative to identify feasible preventive treatments.
MBI can promote changes in neuroplasticity 13 and can facilitate the process of emotional regulation 14 which is a key component of suicidal risk in some disorders. 15 There is evidence that MBI have a positive effect on mediating and precipitating factors of suicidal behavior 16,17 which could potentially make them a preventive intervention for suicide risk.
However, the literature on MBI and suicide risk is mixed. Although there is possibly a relationship between MBI and a lower incidence of suicidal thoughts and behavior, a recent review has identified suicidal behavior as a possible adverse effect of mindfulness. 18 In contrast, three other reviews suggest MBI is effective in reducing suicide risk. [19][20][21] However, one of these reviews did not follow a systematic approach for the literature review process 20 and only half of the articles included in each of the two most recent systematic reviews were in common between them because of use of different selection criteria, 19,21 making it difficult to draw conclusions. Thus, the aim of the current systematic review is to assess the impact of MBI for reducing suicidal thoughts and behaviors using a more comprehensive search strategy.

The Preferred Reporting Items for Systematic
Reviews and Meta-analysis (PRISMA) guidelines were followed for the present review. 22  OR 'suicide behavior') was conducted on all of the electronic research databases mentioned above.

Selection process
All abstracts of articles selected in the searches of each electronic database mentioned above were double screened by two reviewers who evaluated each of the studies against specific criteria, depending on study design. In cases of disagreement, a third author read the full text and discussed each article with the reviewers until a consensus was reached. Additionally, the references from other reviews on the subject [19][20][21] were scanned in order to identify potential additional articles ( Figure 1).

Data collection process
The Rayyan QCRI platform was used to remove all duplicated documents and run the first screening based on title and abstracts, done by two independent reviewers. 23 The platform automatically identifies duplicates and following this process, one of the researchers (KRA) reviewed the articles that were flagged and manually deleted duplicates. Subsequently, using the "blinding on" option, two independent researchers (KRA, LDMS) accessed the platform and carried out screening of articles by reading the title and abstract. Lastly, the full texts of articles were reviewed (KRA, MS, JBB, GOG, MDC).

Data extraction
The primary outcome assessed was suicidal ideation.
We also included secondary outcome measures of suicidal behavior, defined as suicide attempts and suicide deaths.
As we were interested in the effects of the

Study risk of bias and quality assessment
For each paper included in this study, two authors (LDMS, AA) used the Cochrane risk of bias tool to assess the quality and risk of bias for the clinical trials initially selected 24 or used the NHLBI tool to assess the quality of pre-post intervention studies without control groups. 25 In cases of disagreement between evaluators, a third author was called in to break the impasse.

Results
The  Most of the studies presented MBCT as the MBI (n = 10). For this reason, we split the results description into two sections according to the MBI used to better interpret its impact on suicide risk. Table 1  Suicide attempts or suicidal behaviors were part of the outcome of at least 6 studies ( Table 1).   this study and no statistical methods were used. In this study, MBCT seemed to be a promising treatment option for bipolar disorder, particularly for managing subthreshold depressive symptoms. 40 Two studies investigated the impact of MBCT in specific samples. 30,36 One study selected cancer patients (women) who were randomly and equally divided into a control group and an experimental group. 36 Suicidal ideation was measured using BSSI. The goal of this study was to evaluate the effectiveness of MBCT for reducing suicidal thoughts and death anxiety of patients with cancer. The MBCT significantly reduced suicidal thoughts and death anxiety in the experimental group (p < 0.01).
Another study examined Chinese children left-behind by one or both parents to examine the effectiveness of MBI on suicide ideation and other mental health outcomes. 30 The Positive and Negative Suicide Ideation (PANSI) inventory was used to measure suicide ideation.
In this study, participants were randomized to a MBI training group or a waiting list control group. The MBI training group was based on an MBCT protocol. As some of the protocol was designed for working with adults  (Table 3).  Only one study presented no effect of MBI on suicide risk. 33 Another study found conflicting results depending on how suicide ideation was measured. 30 Both studies pointed out that only a small subset of participants had presented with suicidal ideation at the baseline assessment. These results suggest that a possible floor effect could be present that may have influenced the results of the statistical analysis. Furthermore, the way that suicidal ideation was assessed in these two studies was also highlighted as a potential explanation for the results observed. 34 The larger variance in responses and use of more sensitive terminology in item 3 of the HAMD may have facilitated observation of a statistically significant difference. This is particularly important when compared with item 9 of the BDI, 34 which was used as an outcome measure in some of the studies above, but which doesn't allow for as much variance in responses and uses different terminology.
MBI is associated with several positive benefits that might mediate this effect on suicide risk. MBI reduces factors such as impulsivity and depressive symptoms, 12,18 which are associated with a higher risk of suicide. Furthermore, it also improves various cognitive processes like executive functioning 20 and attention 20,27 and increases meta-awareness 42 and self-consciousness. 42 The hypothesis that MBI training increases formal practice of better cognitive processes and a less symptomatic lifestyle and, consequently, leads to lower suicide risk seems very plausible.
Learning mindfulness skills is an important mediator in reduction of depressive symptoms. 39 However, the mechanisms of change involved in this process are as yet unknown. Changes in specific processes, like worry, appear to mediate the effect of MBI intervention on suicidal ideation and depressive symptoms. 29,43,44 The repetitive thinking worry process is considered a proximal risk factor for suicide behavior and is frequently associated with suicide ideation. [44][45][46] It was surprising that MBI did not improve rumination, 36 as formal mindfulness meditation has been associated with improvements in this construct. 47 Furthermore, worry and rumination are highly correlated processes which may suggests that there might be something specific to rumination in the context of suicidal ideation that may need further exploration. 48 Moreover, MBI improves an individual's ability to delineate the prodromal signs and symptoms related to a past suicidal crisis possibly due to memory process and meta-awareness improvements. 42 MBI might target specific processes and collaborate with suicide risk reduction. However, more clinical studies of potential mediators are necessary.
We believe that the most important point that should be highlighted in our work is our research strategy. This Overall, it has been demonstrated that MBI is a feasible and effective treatment for reducing suicide risk, and MBCT in particular, when used with individuals with mood related disorders. Although more research is necessary into MBI as a preventative tool for suicide risk, the current results are promising.

Disclosure
No conflicts of interest declared concerning the publication of this article.