The Benefits of Loving Kindness Meditation for Helping Professionals: A Systematic Review

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Introduction
Work-related stress conditions are a well-documented problem for helping professionals [1,2].Stress is defned as a harmful psychological or physical response to workplace pressures and demands, which can result in poor mental and physical health [3].Beginning in the brain, stress responses activate the sympathetic nervous system, elevating levels of adrenaline and bringing about physiological changes, such as increased heart rate, blood pressure, and respiration [4,5].Prolonged chronic stress may result in physical and mental exhaustion, contributing to long-term problems, such as hypertension, depression, and anxiety [4].
While it is important that helping professionals practice with compassion and empathy, this work is thought to come with a signifcant personal cost.Historically, the terms burnout and compassion fatigue have received considerable attention in the helping profession literature to explain work-related stress conditions [1,[6][7][8].Often used synonymously, these terms broadly describe the evolution of workers' experiences of emotional fatigue and exhaustion.According to Figley and Figley [9], (p.387), compassion fatigue "is the fatigue from dispensing compassion, day after day, year after year," implying that compassion is fnite, depleting, and fatiguing.Continuous, direct exposure to others' emotional distress is the frst pathway to compassion stress and, over time, compassion fatigue [9].Workers who develop compassion fatigue and burnout may experience feelings of sadness, grief, and anxiety, leading to reduced functioning, suboptimal work performance, and difculties with personal and professional relationships [10].Burnout and compassion fatigue are established constructs, with high rates reported in studies among helping professionals; for example, rates of compassion fatigue and burnout amongst physicians are said to be between 40% and 80% [11].Mathieu [10], (p.34), says, "depending on the studies, between 40% and 85% of helping professionals were found to have compassion fatigue and/or high rates of traumatic symptoms."A health survey from the Australian Medical Association found 69% of junior doctors had burnout symptoms and 54% had compassion fatigue [12].Tese and similar studies suggest that compassion fatigue and burnout have undesirable consequences, negatively afecting workers' health and functioning.In considering the work-related fnancial cost of burnout, prepandemic, the World Economic Forum estimated the global economic price to be US $322 billion [13].

Background
Burnout was popularised by Freudenberger after the publication of his Staf Burn-Out article in 1974 [14].At the time, Freudenberger was employed as a psychiatrist at the free drug addiction clinic in New York [15].Stafed mainly by volunteers, he used the term burnout to describe chronic work-related stress, resulting in emotional exhaustion and loss of motivation.Deriving from the illicit drug scene, burnout was used colloquially to describe the harmful efects of chronic drug abuse [15].Considering burnout to be a serious occupational hazard, Freudenberger [16] explains, "Te dictionary defnes the verb "burn-out" as "to fail, wear out, or become exhausted by making excessive demands on energy, strength, or resources."And that is exactly what happens..." (pp.159-160).
In 1976, Maslach et al. adopted the term after coming across it whilst interviewing human service workers.Tis saw a shift in focus from Freudenberger's awareness-raising and prevention work to research that sought to understand the phenomena and concept of burnout, including the development of burnout assessment tools [17].According to Maslach [18], (p. 2), burnout is "a syndrome of emotional exhaustion. .., that can occur among individuals who do "people-work" of some kind.It is a response to the chronic emotional strain of dealing extensively with other human beings".Citing Lief and Fox's technique of "detached concern," or empathic listening and observation without emotional involvement, Maslach [19] thought that the lack of training in such techniques was an infuencing factor in the development of burnout.Physical symptoms of burnout are characterised by exhaustion, psychosomatic complaints, fatigue, headaches, gastrointestinal disorders, and sleeplessness.Emotional signs may include a lack of patience, irritation, anger, and depression [20], whereas burnout may afect people in any profession and is more likely in stressful work environments [21], compassion fatigue is considered specifc to helping professionals, particularly those who repeatedly witness the emotional distress of others [22].

Compassion Fatigue and Empathy.
Compassion fatigue was introduced into the nursing literature to describe a unique form of burnout seen in the profession, resulting in feelings of anger, depression, and inefective practice [22].Joinson [22] says, "unlike burnout, compassion fatigue is linked directly to particular people: nurses, ministers, counsellors, and others in the caregiving professions" (p.116).Joinson borrowed the term after Edward Poliandro of the Mount Sinai Medical School presented the concept at a social work conference in 1989 [23].Pugh [23] says "doctors, social workers, and therapists are giving a new name to a syndrome they say is draining their ranks: compassion fatigue." Figley considers compassion fatigue a more user-friendly and less stigmatising term than secondary traumatic stress [24], establishing the concept in the helping profession literature.Figley [25] says, "the very act of being compassionate and empathic extracts a cost under most circumstances.In our efort to view the world from the perspective of the sufering we sufer" (p.1434).Considering empathy to be essential to psychotherapeutic practice, Figley [25] links empathy to compassion fatigue, describing empathy as a process where the worker projects themselves "into the perspective of the client.In doing so, the psychotherapist might experience the hurt, fear, anger, or other emotions experienced by the client" (p.1437).Tinking that workers may automatically absorb clients' emotional suffering, Figley [26] says, "those who have an enormous capacity for feeling and expressing empathy tend to be more at risk of compassion stress" (p. 1).When developing his etiological model for compassion fatigue, Figley paradoxically proposed that empathy lies at the root of compassion stress, which eventually leads to compassion fatigue [27,28].
Carl Rogers is widely considered to be an eminent fgure in the feld of psychotherapy, with his dissemination of ideas around "therapeutic empathy" into the helping profession literature resulting in empathy being regarded as an essential therapeutic skill [29], also see [30].Although empathy is defned in many diferent ways, there is agreement that it is made up of distinct cognitive and afective components, which allow us to comprehend others' internal states, whilst maintaining a self-other distinction [31,32].Cognitive empathy-sometimes referred to as mentalising or perspective taking-is where one intentionally adopts another person's perspective in an attempt to cognitively understand how they are thinking or feeling [33], whereas afective empathy is said to occur via a vicarious sharing of another's emotions [33].While empathy is considered to support positive therapeutic relationships and motivate altruistic behaviour, empirical evidence from social psychology and the neurosciences suggests that the reliance on afective empathy may be maladaptive and may contribute to empathic distress [11,34].
Te concept of compassion fatigue has brought awareness of the extent and nature of work-related stress conditions; however, it has recently come under scrutiny.In nursing [28,35] and medicine [36], it has been suggested that compassion fatigue is a poorly defned term, which "rests on a most fragile foundation" [35], (p.2046), that "has largely been unchallenged and remains poorly understood" [28], (p.20).Researchers propose that compassion fatigue is a misleading term, as compassion is said to foster emotional well-being and empathic distress is the primary source of workers' problems, arguing that "compassion fatigue should be replaced by the term "empathic distress fatigue" [11], (p.368).Empirical studies using functional magnetic resonance (fMRI) show that the neural substrates for compassion and empathy are distinct [37][38][39], whereas compassion activates the dopaminergic and oxytocin regions, associated with afliation and reward, afective empathy activates the pain matrix and the amygdala [32,37,38].Compassion, therefore, is said to be neurologically rejuvenating, bufers against negative afect, and potentially prevents burnout [40][41][42][43].
Compassion is commonly defned as a sensitivity to the sufering of others and a desire to alleviate that sufering and is characterised by feelings of concern, warmth, and care [33,42].Compassion has several components: awareness, 2 Health & Social Care in the Community concern, intention, and motivation to help others [44].Te number of studies on contemplative practices that seek to understand the components associated with compassion has been growing over the last decade, yet this has not come without some criticism [45].Tang et al. [45] point out that fndings for many studies require replication, there is a risk of bias as some researchers are also meditation enthusiasts, and sample sizes are often small.According to Fox et al. [46], although more work is required to build on fndings, the increasing number of high-quality studies assures that "diferent practices show relatively distinct patterns of brain activity and that the magnitude of associated efects on brain function may have some practical signifcance" (p.225).

Research Aims.
Tere is accumulating scientifc evidence which suggests that certain forms of compassion practice, such as loving kindness meditation (LKM), ofer efective ways of reducing stress and increasing positive afect, making workers less vulnerable to maladaptive stress responses, such as empathic distress [11,40,47,48].Te key diference between compassion and LKM is that LKM is specifcally directed toward sufering [40].Rooted in the Teravada Buddhist traditions, LKM aims to cultivate compassion, warmth, connectedness, and kindness towards ourselves and others [49].Te process of LKM traditionally begins with the development of feelings of kindness, love, and compassion towards oneself and then is extended to friends, family, and loved ones and eventually to neutral people, enemies, and all living beings [40].In recent times, LKM practice has been adapted to meet specifc research interests and is beginning to be thought of as a viable strategy which may counter negative health concerns, such as stress, as seen in health-related settings [40].Given the serious negative consequences attributed to burnout and compassion fatigue, we argue that prevention interventions are essential.While compassion fatigue continues to be of considerable interest and a promising area of research within the helping profession literature, compassion is a neglected topic.Our intent is not to provide an indepth scientifc discussion, rather our objective is to provide an overview of the research literature that has a specifc focus on LKM as a practice supporting the development and maintenance of compassion.Hence, in this systematic review, we aim to investigate the efectiveness of interventions involving LKM.Tese new insights aim to provide a basis for further discussion on compassion and compassion-based interventions that may mitigate, or prevent, negative health consequences for those working in the helping professions.

Methodology.
Te seminal fMRI study by Singer et al. [50], which investigated and demonstrated the neural activations involved in empathic responses to pain, attracted immense scientifc interest and was considered the seed article that sparked social neuroscientifc interest in social emotions [51].Following this, Singer and colleagues published two other highly infuential studies on compassion: Diferential Pattern of Functional Brain Plasticity after Compassion and Empathy Training (paper 1) [52] and Functional Neural Plasticity and Associated Changes in Positive Afect after Compassion Training (paper 2) [53].Inspiration for our research paper came from these two studies.Following the key guidelines for systematic reviews as provided by the Centre for Reviews and Dissemination [54], a citation search was used to locate relevant articles that cited Klimecki et al. [52] and Klimecki et al.'s [53] studies.In May 2021, a SCOPUS search located 223 articles for paper 1 and 273 for paper 2. After removing duplications, 418 articles remained.A follow-up manual search of reference lists from meta-analysis papers found in the original citation search, such as Fox et al. [46] and Kim et al.'s [55] studies, was carried out to locate additional studies investigating LKM, revealing another 7 articles to include.To identify any other articles that may have been missed in the original search, the ProQuest, Scopus, and Web of Science databases were searched using a date range from July 2013 to May 2021.Te search string consisted of terms considered to be within the scope of this review.Te keywords were loving kindness AND fMRI OR MRI; compassion training AND fMRI OR MRI; compassion meditation; compassion OR loving kindness AND emotion regulation; positive afect AND fMRI OR MRI; mental training; and amygdala AND compassion.No additional articles were found.Te 425 articles were screened by title and abstract, and 283 were removed for not meeting the inclusion criteria, which were as follows: (a) published in a peer-reviewed journal, (b) original research, (c) written in the English language, (d) samples comprised of either novices or expert meditators, (e) included healthy adult participants only, and (f ) the study included an intervention primarily made up of LKM, or more than 50% of the exercises were LKM.Where this was not evident in the abstract, the full text was retrieved (n = 142), and the study was excluded if it did not meet the inclusion criteria (n = 127).Seventeen articles, including the two seed articles, were included in this review (Figure 1).All authors assessed the quality of each article using the checklist for assessing the quality of quantitative studies (QualSyst) [56], and any diferences were resolved until 100% agreement was reached.Comprising of 14 items, each study was rated against the items on the checklist and scored on the extent to which they met the specifc criteria (yes = 2, partial = 1, no = 0).N/A was permitted for 5 items, if not applicable to the study design.Te overall score for each study was converted to a percentage (0-100), scores ranged from 68% to 92%, with a median of 80.5%.

Results
Of the 17 included studies, all clearly described their study designs in sufcient detail to allow for replication.Several distinct designs were employed, such as solely fMRI (1), fMRI with another measure (6), solely MRI (1), MRI with another measure (1), questionnaire (1), solely self-report (3), self-report with another measure (1), spectral frequency (1), blood samples (1), and a video task (1).Te included articles also investigated the efectiveness of a range of compassionrelated interventions based on LKM, such as brief compassion training of novices [52,57,58], others only included long-term meditators [59,60], and some compared compassion training with other interventions, such as reappraisal, sitting quietly, empathy, or mindfulness [52,59,61].A close reading of the included articles found that the operational process of LKM was broadly consistent across the studies, except for [62].Lutz et al.'s.[62] research was based on LKM; however, the expert meditators had trained in Tibetan traditions which were not entirely rooted in Teravada.Also, the novices' instructions for LKM difered slightly from traditional LKM practice.Te objectives for each study were also clearly described and diverse.Fredrickson et al. [63], for example, tested the efects of LKM on the participant's positive emotions, personal resources, and overall life satisfaction, whereas Leung et al. [64] sought to examine grey matter diferences between novice and expert mediators, and Le Nguyen et al. [61] examined the impact of LKM on telomere length.
All of the studies passed QualSyst screening; however, there were some areas of weakness.As neuroimaging is resource-intensive, sample sizes are often low, and a sample of at least 40 is considered satisfactory [65].Of the 7 included fMRI articles, three exceeded 40 participants, and four had under 30.Of the two MRI studies, one had 25 [64] participants and the other had 332 [66] participants.Due to the paucity of published studies related to our topic, we decided that no article would be excluded based on sample size.Although there were no common weaknesses across the remaining articles, for some, the recruitment method meant that participants had an interest in or were open to learning meditation, such as in Fredrickson et al. [63] and Kok et al.'s studies [67].Furthermore, most of the articles restricted recruitment to particular populations, such as university students, or staf [58,67,68], or meditation experts [59,62,64].Terefore, results may not be generalisable to other populations, such as in healthcare settings.Studies with small samples would require replication in larger samples to confrm fndings.
Blinding of participants in studies such as these is not always possible as they may know which intervention they will be receiving.As a control, Klimecki et al. [53] did not make the participants aware of the intervention until they had entered the training phase.Seppala et al. [68] used a cover story and random selection for either intervention.Polizzi et al. [58] named their studies, experiences 1, and refections, whereas Fredrickson et al. [63] and Kok et al. [67] did not describe LKM or provide any other information that may have led to the demand efect.Le Nguyen et al. [61], Weng et al. [69], and Fredrickson et al. [70] randomly assigned to the experimental condition (LKM, memory, etc.).Blinding of expert meditators was not possible as they were purposely selected for their expertise, and so fndings should be interpreted with caution.
Taken together, the included studies show promise that LKM may be an efective and practical tool that enhances positive afect and overall well-being.LKM also shows promise as an emotional regulation strategy (see Table 1 for a summary of key fndings).Te main fndings are summarised and discussed in the following sections.Te approach of comparing expert meditators' neural responses to those of novices, who had undergone one week of LKM training, was frst employed by Lutz et al. [62].Results revealed that the experts showed greater activation in regions associated with empathy during meditation than the novices whilst listening to emotional sounds.However, neural brain regions previously associated with afective empathic responding to another's pain, such as the limbic system and middle insular, were modulated whilst the experts were in a voluntary compassionate state.Also, the experts had greater activation in brain circuitries previously linked to theory of mind than the novices [62], suggesting that compassion may enhance cognitive processing.Te fndings of this study demonstrate that the state of LKM is linked with activity in neural brain regions associated with both empathic arousal and cognitive control.Tus, LKM may be efective in emotion regulation through a combination of afective empathic responses being downregulated and greater recruitment of cognitive processing.

Summary of
In Klimecki et al's.[52] research, fMRI data were analysed to determine if compassion training (compared to a memory control group) produced functional neural plasticity.fMRI data was obtained whilst both groups were exposed to high empathy (HE) videos.Posttraining results demonstrated that only those in the compassion group (1) experienced an increase in positive afect, and (2) there was strengthened activation in neural regions associated with the care and social connections systems.By comparison, precompassion training exposure to the HE videos produced a negative afect and activation in neural regions formerly related to the empathy for pain response.Findings suggest that training in compassion may counter negative emotional efects related to the activation of the empathy for pain networks, such as anger, sadness, fear, and distress.In other words, compassion training may be protective for workers who practice in conditions that elicit a high afectiveempathic stress response.Also, this study was the frst to demonstrate that short-term compassion training changes neural functioning and neural changes are specifc to regions that have previously been implicated in afliation and caregiving.Tis is important as these regions are associated with the release of neuropeptides such as oxytocin and dopamine.Growing evidence suggests that these neuropeptides have benefcial efects on health through their ability to downregulate the threat and stress response [57,74].Also, as compassion fosters afliation, practices of this type may cultivate a feeling of connectedness and closeness between oneself and others.Connectedness and closeness have been associated with prosocial behaviours, meaning we are motivated to cooperate and help others when they are in need [34].
Furthermore, Klimecki et al. [53] trained novices in either compassion or empathy or memory control.Findings demonstrated that empathy training elicited more negative afect, whereas compassion training increased positive afect.Notably, the neural pathways associated with empathy for pain increased in activation after empathy training.After compassion training, there was increased activation in neural regions associated with social connection and reward.Tis demonstrates that neural functional plasticity is nonoverlapping and distinct between empathy and compassion training.Te implication here is that compassion ofers a route to positive afect, whereas empathy tended towards the opposite.In other words, compassion may help ameliorate distress and burnout associated with emotionally distressing work contexts.
Te subjective fndings by Fredrickson et al. [63] strengthen former studies on the benefts of loving kindness training on well-being.Fredrickson et al. [63] reported an association between LKM practice and self-reported increases in positive emotions, which steadily rose over the 6week training period.Teir results suggest that there is a dose-response correlation between the practice of LKM and positive emotions, tripling over the time of the study.Furthermore, fndings indicated that (1) positive emotions are generated during LKM sessions, (2) even after the sessions have ended, they persist, and (3) repeated LKM practice, over time, resulted in a cumulative increase in positive emotions.Tese shifts in positive emotions were connected to increases in various personal resources, such as positive relationships with others, better physical health, and increased attention.Fredrickson et al. [70] found that both mindfulness meditation and LKM were equally connected to increases in participants' everyday experiences of positive emotions, suggesting that these meditation practices may improve people's physical and mental health.Seppala et al. [68] support this view, saying that a single 10-minute session of LKM is a cost-efective tool that can potentially be applied by most people to increase feelings of well-being as well as compassion towards others.Conversely, Polizzi et al. [58] reported that although LKM resulted in greater compassion for others compared to the control group, a 15-minute single session of LKM practice was not sufcient enough to elicit gains in psychological functioning.Tis implies that training duration matters and it seems logical that having more experience in LKM practice will have some beneft in terms of skill and expertise.Currently, however, there is not enough research specifc to the efects of training length to draw upon, especially as the included studies for this paper did not explicitly address a correlation between the lengths of training time and longer-term benefts.Terefore, further research is required.Despite this need, the implication is that LKM is a promising technique that can be deployed to ameliorate the negative afective responses associated with empathic distress.
Similarly, Valk et al. [66] argue that the type of training matters.In their longitudinal MRI brain imaging study of novices, results provided evidence that structural brain plasticity and correlated individual improvements in attention difered between three diferent training modules: presence, afect, or perspective.Te goal of the presence module was to teach participants to be present in the moment, by calming their minds (attention) and raising their awareness of their bodily states (interoception).Tese were trained through a breathing meditation and body scan exercises.Te two core exercises for the afect module were LKM and a contemplative dialogue exercise, in which paired participants sat facing each other, whilst one asked a question, the other listened but did not respond.Tis activity focused on the experience rather than any thoughts, such as accepting difcult emotions.For the perspective module, the focus was on developing cognitive abilities, where the two exercises were an observing-thoughts meditation and a perspective-taking task.
In the presence module, participants reported improved attention with MRI data showing increased thickness in brain regions associated with learning.Te afect module group reported enhanced compassion and structural thickening was observed in the emotional regulation, selfperception, and introspection regions.Te perspective module group had increased thickness in areas associated with theory of mind (TOM) and self-perspective inhibition.Valk et al. [66] concluded that gray matter selectively increases in areas that support various cognitive functions.Leung et al. [64] also noted brain gray matter diferences between their sample of novices who had completed 7 hours of home-based training compared to experts.Although results need to be interpreted cautiously because of the small sample size, MRI analysis revealed that, compared to the novices, the experts had notably more gray matter volume in regions associated with TOM, emotional regulation, selfcontrol, and motivational behaviour.Importantly, increases in the right posterior parahippocampal gyrus (RPPG) in the experts were considered noteworthy, as the RPPG is part of the limbic system and neocortical regions which work together to regulate emotional and empathic responses.Overall fndings indicate that LKM may increase gray matter in regions associated with emotion regulation, suggesting that LKM may play a role in counteracting negative afect associated with empathic burnout.
Te idea that LKM may be employed as an efective emotion regulation strategy was proposed by Engen and Singer [59], who suggested that compassion may moderate negative empathic responses to others' sufering.Data from their fMRI study of expert meditation practitioners found that compassion activated regions associated with positive afect, suggesting that it may be efective in generating positive emotions.Engen and Singer [59] proposed that compassion could increase resilience in the helping professions when employed as an emotion regulation strategy.A later fMRI study by Engen et al. [60] of experts and a novice control supports the idea that LKM may foster resilience by generating positive emotional states.Engen et al. [60] demonstrated that the experts had signifcantly increased thicknesses in brain structures ranging from the anterior insular cortex to the ventrolateral prefrontal regions when compared to the control.Tis suggests that these regions are fundamental in the generation of LKM, and LKM functionally and structurally afects these regions.Te anterior insular is associated with interception, attentional processing, and general awareness.Te ventrolateral prefrontal region is often recruited during reappraisal in which interpretation of a negative stimulus minimises emotional impact, indicating that activation of the ventrolateral region may be key to the generation of positive emotional states during LKM.Likewise, in Leung et al's.[71] fMRI study of experts and novices, evidence indicated that meditation experts could maintain the duration of positive feelings compared to that of novices.Similar to Engen and Singer [59], Leung et al. [71] also found downregulation in the amygdala.Te experts experienced lower levels of negative emotions in comparison to the novices, suggesting that longterm meditation may be connected to the extinction of negative emotions and the cultivation of positive emotions.As such, compassion could be viewed as an emotionregulation strategy.
Te fndings of this review ofer evidence in support of compassion training as a method for supporting professionals in roles that elicit high emotional valence.Compassion as an emotional regulation strategy was frst proposed by Engen and Singer [59] and later tested by Weng et al. [69] and Hildebrandt et al. [72].Although Weng et al's.[69] results need to be interpreted with caution due to the small sample size, fMRI data obtained from novices trained in either reappraisal or LKM demonstrated that compassion, but not reappraisal, signifcantly regulated emotional responses to sufering by mediating psychological arousal through decreased activation in the amygdala.While decreased psychological arousal may mitigate empathic distress, compassion also facilitates prosocial engagement [69].
Te purpose of Hildebrandt et al's.[72] study was to determine which contemplative cognitive training practices facilitated specifc emotional regulation strategies.Training in either a presence (meditation and body scan), afect (LKM), or perspective (perspective-taking, or TOM) modules resulted in participants self-reporting the benefts of their assigned training strategy.Findings showed that (1) relevant self-rated emotional regulation strategies were not induced in the presence module, (2) the strongest efect on cognitive reappraising and acceptance was seen in the perspective module, and (3) the afect module increased acceptance and positive ratings while decreasing avoidance of difcult emotions.
Supporting Hildebrandt et al.'s [72] work, Trautwein et al. [73] also tested the efects of training in either presence, afect, or perspective taking.In their study, data were obtained through the novel video-based task, EmpaToM.EmpaToM infuences empathic afect sharing and TOM by presenting videos of an individual recounting an autobiographical episode that difers emotionally.To assess afect, after each video, the novice participants rated the amount of compassion they felt for the person, and for TOM, they were presented with three multiple choice questions which required inference of the person's mental state, only one question was correct.Results revealed that the diferent training practices had specifc efects on cognitive and social functioning.In the presence module, driven by improvements in executive control, general attentional performance increased.Compared to presence and perspective training, LKM training had the strongest efect on compassion, increased positive afect, and improved attention.Health & Social Care in the Community Te perspective module was the only module to have a meaningful efect on TOM performance, supporting the view that, working diferently from other strategies, compassion-based practice can be regarded as an alternate route to successful emotion regulation.As contemplative neuroscience grows as a discipline that seeks to identify the brain's neural pathways for compassion, parallel scientifc investigations of physiological states generated through compassion have started to become of interest.Kok et al. [67] analysed vagal tone measures of the novice participants against a control, pre-and post-LKM training, as well as self-reported data.Vagal tone is a fundamental part of the autonomic nervous system, meaning it is not under conscious control.A high, or "healthy" vagal tone, is associated with improved cardiovascular health and emotion regulation [75].Kok et al. [67] found that LKM produced increased self-perceived social connections and positive emotions relative to the control.Furthermore, the increase in positive emotions encouraged participants to connect socially, and in turn, positive social connections increased vagal tone, thus potentially creating a resource that is benefcial to good health.Kok et al's.[67] study has gone some way in demonstrating the association between the efects of LKM practice and improved vagal tone, which over time may be self-sustaining.
Taking a diferent approach Le Nguyen et al. [61] sought to determine if LKM and mindfulness meditation (MM) difer in their efects relative to a control on telomere length.DNA was extracted from the novice participants' blood samples pre and posttraining.Telomeres allow chromosomes to replicate properly during cell division, each time a cell divides, and as we age, telomeres shorten.Of note, oxidative stressors such as diet, smoking, and stress are signifcant factors that result in shortening during replication [76].Results showed that telomeres shortened across all experimental conditions, but more so in the MM and control groups.In the LKM group, daily practice of LKM seemed to bufer against attrition, with less shortening over time, appreciably less than the control group.

Discussion
We began our paper with the observation that workers in the healthcare professions have been long perceived as at risk of developing burnout and compassion fatigue.We also observed that empathy and compassion are often used interchangeably, but they have been demonstrated to have distinct components.To recap, empathy has been understood as having two major components: afective and cognitive [37].Compassion is underpinned by the cognitive empathy process involved in perspective-taking and caring motivation in noticing the sufering of others [33].Tis review was sparked by interest in what would support the development and maintenance of compassion in the helping professions.While recognising the importance of contextual and individual diferences, we ofer four main discussion points: (1) the type of training matters; (2) LKM can ofer workers a method for supporting compassion towards others; (3) regular LKM practice may assist in reducing stress and enhancing the well-being of helping professionals; and (4) education about the theory of compassion and empathy should take into account new evidence and ofer students and workers efective compassion-enhancing meditative techniques, of which LKM is one.
It has been increasingly appreciated that contemplative practices are efective in increasing resilience and well-being [59].Recently, researchers have turned their attention to the question of whether LKM can be taught, whether it is benefcial, and how it difers from other practices.As demonstrated in the included studies, LKM can be taught, but more importantly, the type of training matters, as compassion appears to be markedly diferent from reappraisal and theory of mind, for example [66,72].Compassion has the potential to increase overall well-being and positive afect and regulate emotions, whereas, for the other training methods, this is not necessarily so [69,72].Tis has important implications for those working in the helping professions such as healthcare settings because burnout and compassion fatigue have been identifed as signifcant issues that can negatively impact patient care and staf retention [13].Identifying efective training techniques is essential, as they can be employed to promote resilience and bufer against stress [40,41], and such outcomes are important, particularly for those employed in environments where they are repeatedly exposed to the sufering of others.
As a whole, there is encouraging evidence from the included articles that training in LKM, or courses including LKM, cultivates the ability to experience compassion towards others [52].Novice participants in the included studies reported a range of benefts from engaging in the training such as strengthened feelings of care towards themselves and others, increased positive emotions which persisted over time, improved relationships, and greater compassion towards others [69,73].Of note, we found in some studies that participants were able to manage distressing situations as training strengthened positive afect [52,63].Consequently, the generation of compassion is not only benefcial to oneself by providing a potentially efective coping strategy but also helps others.Although LKM studies including a sample of healthcare professionals are yet to be published, we suggest that it is plausible that similar efects would be seen in such a sample.
Although LKM primarily uses emotional and visual strategies to cultivate compassion, compassion is also supported through afective and cognitive neural pathways [37].As such, compassion training shows promise as an efective emotion regulation strategy, fostering positive afect for workers who are exposed to the distress of others.Regularly cultivating compassion in the form of LKM may ofer increased protective factors against the risks of stress, whilst enhancing overall well-being.When responding to a client's distress with compassion, rather than becoming emotionally roused, the worker acknowledges the distress, and thus they are more able to regulate their own emotional response.By contrast, if a worker responds with an afective empathic response, they are at risk of identifying with the sufering of their client, potentially leading to emotional distress and, over time, a negative health outcome.Evidence suggests that Health & Social Care in the Community compassion training may help workers who practice in conditions that elicit a high afective empathic stress response [59,64,66].
It would be helpful to introduce LKM-based interventions into training courses and work-based settings.We encourage educators and helping professionals to revise their thinking about compassion in favour of the term empathic distress.Compassion serves as a bufer against adverse health and psychological problems, therefore benefting the person who experiences it.Our research underscores the importance of training helping professionals in practices, such as LKM, as a potent strategy for improving workers understanding of the efects of afective empathy, causing fatigue and stress on their minds and bodies.By educating workers, we can create supportive environments that enhance their ability to provide sustainable, compassionate care to others.

Conclusion
Tis review examined Figure 1 scientifc literature which investigated the compassion-enhancing practice of LKM.Based on the fndings found in this paper, we suggest that LKM can be seen as an alternate strategy to reduce stress, ease empathic distress, and increase positive afect.Saying that, since none of the samples in the included articles were specifc to healthcare professionals, fndings from our review can only be tentatively generalised to this population.Despite this limitation, it is reasonable to posit the idea that fndings could be generalised; however, research employing a sample of healthcare professionals would be benefcial.Also, whilst acknowledging that available studies are sparse, evidence from compassion-based research is suggestive of LKM training shaping outcomes through a range of compassion-related pathways, such as the capacity and motivation respond to the needs of others, whilst also being physiologically and emotionally benefcial.We suggest that additional research aimed at how to best train educators and individuals in compassion skills is needed to support the sustained development of compassionate care.For example, compassion practices derived from Buddhist traditions equip individuals with the tools to cultivate and sustain a more resilient, compassionate, and emotionally regulated self.Finally, we suggest that the cultivation of compassion is potentially protective, and at this stage, it would be more helpful for compassion fatigue to be thought of as empathic distress fatigue.

Table 1 :
Findings.Te results of this systematic review suggest that training in the compassion of LKM fosters benefcial changes through changes in brain structures, neural plasticity, and physiological responses.To determine how LKM may cultivate such change was approached in several ways in the included studies.One was Summary of included articles.