The effects of meditation on individuals facing loneliness: a scoping review

Background Meditation is defined as a mind and body practice focused on interactions between the brain, mind, body, and behaviour, containing four key elements: a quiet location with little distractions, a comfortable posture, a focus of attention, and an open attitude. We sought to review the benefits of meditation on the alleviation of loneliness. Methods A scoping review was conducted based on Arksey and O’Malley’s five-stage framework. Eligibility criteria included primary studies of any type that investigated the effects of meditation on loneliness. Search strategies were developed and conducted on MEDLINE, EMBASE, AMED, and CINAHL. The National Center for Complementary and Integrative Health, and American Psychological Association websites were also searched. Articles meeting the inclusion criteria were critically reviewed using a descriptive-analytical narrative method. Results Thirteen studies met our inclusion criteria and were published between 2012 and 2020 across 10 countries. Eleven studies reported improvements in relation to loneliness. Of the remaining two studies (15%), one mentioned the alleviation of loneliness, but only looked primarily at social closeness in lonely individuals. The other study found a correlation between loneliness and nuclear factor (NF)-κB levels, which was the measured outcome; however, the direct effects of meditation on loneliness were unclear. Three main themes emerged from our analysis, as follows: 1) positive results across all studies, 2) relatively small randomized control trials conducted over the last decade, and 3) lack of diverse demographic information. Conclusions While a small number of studies exist at this intersection, given all included studies indicated positive findings, the effects of meditation in alleviating loneliness are promising. Future research should be directed at understanding how meditation mitigates loneliness and how this intervention can impact practice for healthcare professionals.

mechanisms, specifically the neurobiological mechanisms called S-ART [5]. This refers to self-awareness, self-regulation, and self-transcendence [5]. Meditative practices overall focus on navigating difficult emotions and feelings [6]. Mindfulness practices, such as lovingkindness meditation specifically, which helps to create unconditional kind attitudes towards others and oneself [7], has been shown by Hutcherson et al. [8] to increase feelings of social connectedness and consequently decrease feelings associated with social isolation. Therefore, mindfulness meditation training can be a successful tool to implement in order to reduce feelings of isolation due to the downregulation of the expression of inflammation-related genes, which are parallel to reductions in loneliness [9].
While there is no universal definition for the term 'loneliness' , it is commonly defined as a state of solitude or being alone [10]. Loneliness can also be defined as the perception of being alone, which constitutes having a negative state of mind associated with deficient social relations rather than actually being alone, due to the various forms of loneliness that exist: (1) chronic loneliness and (2) reactive loneliness [10,11].
Currently, loneliness is likely to be exacerbated as a result of the coronavirus disease 2019 (COVID-19) pandemic, due to a decrease in regular modes of communication, such as intimate interactions and face-to-face contact, as well as due to a more vulnerable aging population, who, under normal circumstances, disproportionately face loneliness [12,13]. Before the World Health Organization declared the COVID-19 pandemic [14], the prevalence rates of loneliness and social isolation were already known to be between 10-40% across the United States, China and various European countries, that it was being described as a "behavioral epidemic" [15]. This was specifically being seen in older adults, with both conditions co-occurring frequently [15]. The susceptibility of loneliness in older adults is due to various factors, such as living alone or a lack of familial connections, reduced connections to one's culture of origin, loss of friendship networks and associated problems in creating new ones, among others [13].
During the beginning of the pandemic between January and May of 2020, there had already been a statistically significant increase in loneliness (interaction-p = 0.018) measured based upon a three-item Loneliness Scale, which included the 3 following items: feeling "that you lack companionship", "left out", and "isolated from others" [16]. This was most often associated with a reduction in social supports, resulting from the pandemic-associated restrictions that were implemented [16]. As such, negative behavioural health impacts associated with the pandemic posed a threat of worsening after the initial outbreak, including loneliness, which can cause increases in depressive symptoms [16]. While it is challenging to fully identify the extent to which this has occurred to date, evidence exists suggesting that lockdown policies and self-isolation protocols have been found to have negative impacts on the levels of loneliness experienced by individuals both during and after lockdown [17]. Due to the increasing public health issue of loneliness and its effects on health and well-being, alleviation of feelings of loneliness through therapies of value can result in positive health outcomes, such as a lower risk for physiological dysregulation and inflammation [18]. The pandemic has also brought with it an increase in the usage of meditation apps [19]. While it is known that loneliness causes adverse health outcomes and meditation has been linked to its alleviation, the sum benefits identified by research remain unknown. To date, the quantity and type of studies investigating the effects of meditation on loneliness has not been indicated by the literature. Therefore, this was the purpose of this study, using a scoping review methodology.

Approach
Scoping reviews are used to review a body of literature and are defined as studies that aim to map the literature on a particular topic or research area and provide an opportunity to identify key concepts; gaps in the research; and types and sources of evidence to inform practice, policymaking, and research [20]. A scoping review investigating the effects of meditation on loneliness was conducted based on Arksey and O'Malley's [21] five-stage scoping review framework. The five steps are as follows: (1) identifying the research question, (2) identifying relevant studies, (3) selecting the studies, (4) charting the data, and (5) collating, summarizing, and reporting the results.

Step 1: identifying the research question
The purpose of the present scoping review was to identify the quantity and type of studies investigating the effects of meditation on loneliness. Study eligibility was based on a Population, Intervention, Comparison and Outcomes (PICO) framework. Eligible populations included adults aged 18 years and older experiencing loneliness. With respect to interventions, meditation and other mindfulness related practices, such as mindfulness-based stress reduction (MBSR) were the focus of this study and the basis for eligibility; we excluded any therapies with no meditation-specific component (i.e. yoga as a form of exercise). There were no comparisons. Outcomes included a summarization and thematic analysis of findings across all eligible articles.

Step 2: finding relevant studies
Following preliminary searches of the literature, search strategies were developed for and conducted on MED-LINE, EMBASE, AMED, and CINAHL databases. The National Centre for Complementary and Integrative Health (NCCIH), and the American Psychological Association (APA) websites were also searched for eligible primary research articles and scoping or systematic reviews evaluating outcomes on use of meditation in individuals facing loneliness. Reference lists of scoping and systematic reviews were also reviewed for other potentially eligible primary research articles not captured by our search strategies. The search, designed by GKS and JYN, included literature published from database inception up and including the week of April 22, 2020. Terms searched included "breathing exercise(s)", "loneliness", "meditation", "mind-body therap(ies)", "mindfulness", "patient isolation", "relaxation therap(ies)", "social distance", and "social isolation". These terms were identified following a review of indexed headings and keywords of articles found in our preliminary searches. A sample search strategy is provided in Table 1.

Step 3: selecting the studies
Only primary research articles evaluating the effect of meditation on loneliness were included for the purpose of this scoping review. Articles were excluded at this stage if they did not make reference to our research objective of alleviating loneliness using meditation. If studies identified or measured outcomes resulting from the effects of meditation on loneliness, they met our inclusion criteria; this was true regardless of whether these aforementioned outcomes were designated by the study as primary or secondary. Publications in the form of protocols, abstracts, letters, editorials, case reports or case series were not eligible. We also restricted our eligibility criteria to articles published in the English language, those that involved adult populations (aged 18 +), and that were either available publicly or could be ordered through the McMaster University library system. All authors (GKS, SBH, ZT, and JYN) initially pilot-screened a subset of the titles and abstracts independently and then met to discuss and resolve discrepancies. Following deduplication, all search results were independently screened in triplicate (GKS, SBH, and ZT). All four authors then met, and any discrepancies were resolved; in the case that a consensus could not be reached, a majority vote was held (between GKS, SBH, and ZT) following discussion with the supervising author (JYN).

Step 4: charting the data
The articles that met the inclusion criteria were critically reviewed using Arksey and O'Malley's descriptive-analytical narrative method [21]. For each eligible article that was included, the following data was then extracted and charted: article title, author(s), year of publication, study country, study setting, study design, population type and sample size, definition of loneliness, type of meditation used, duration of meditation, the occurrence of a followup (and duration), primary and secondary outcomes and how they were measured, main findings, challenges encountered, and conclusion. GKS and JYN developed the data extraction forms. GKS, SBH, and ZT completed data extraction for a subset of the eligible articles and then met to discuss and resolve any discrepancies. This was followed by the three authors (GKS, SBH, and ZT) completing a full data extraction of all the eligible articles independently and meeting to discuss and resolve any discrepancies, with JYN resolving discrepancies within both the pilot and final data extraction sets when a consensus was unable to be reached.
Step 5: collating, summarizing, and reporting the results Charted data was summarized in the format of tables, followed by descriptive data being analyzed using thematic analysis. GKS reviewed the entire set of data, while SBH and ZT reviewed subsets of the data. JYN and GKS identified codes relative to the findings, organized codes into thematic groups, and presented a narrative relating to the research question, as well as highlighted knowledge gaps in the currently existing literature. All four authors then met to discuss and resolve discrepancies.

Eligible article characteristics
Thirteen studies met the inclusion criteria and were published between 2012 and 2020 and conducted across 10 countries [9,[22][23][24][25][26][27][28][29][30][31][32][33]. These articles originated from the United States (n = 7); Australia (n = 1); Germany (n = 1); India, Nepal, Myanmar, and Sri Lanka (n = 1); Iran (n = 1); South Korea (n = 1); and Spain (n = 1). Of the 13 articles, 8 were randomized controlled trials (RCTs), 2 were feasibility studies with an RCT design, 1 was a feasibility and acceptability study, 1 was a pilot study looking at feasibility, and 1 was a quasi-experimental study. Six of the 13 studies (46%) used meditation in combination with other interventions, such as yoga. The remaining 7 studies (54%) used meditation as the only intervention, the types of which included cognitively based compassion training, brain education-based meditation, tai chi meditation, and mindfulness-based stress reduction training. Ten out of 13 studies (77%) looked at loneliness in some aspect as a primary outcome, while 3 out of 13 studies (23%) looked at loneliness as a secondary outcome. General characteristics of all eligible studies are found in Table 2 and details specific to findings and outcomes are found in Table 3. Additional demographic characteristics of all eligible studies are provided in Table 4.

Summary of eligible article findings
Eighty-five percent of the studies (11 out of 13) identified positive improvements in participants' feelings of loneliness. Of the two remaining studies, one mentioned the alleviation of loneliness, but only looked primarily at social closeness in individuals experiencing loneliness. The other study found a correlation between loneliness and participants' nuclear factor (NF)-κB levels, which was the measured outcome; however, the direct effects of meditation for loneliness were unclear.

Findings from thematic analysis
In total, three main themes emerged from our review and are described below.

Positive results across all studies
Upon accounting for all eligible articles, one immediate and striking finding included that all thirteen of the studies reported positive findings for at least one of their respective outcomes [9,[22][23][24][25][26][27][28][29][30][31][32][33]. Of these studies, 11 out of 13 (85%) studies identified improvements in relation to loneliness [9, 22-27, 29-31, 33]. Of these 11 studies, 7 (64%) studies identified a significant decrease in loneliness within their intervention groups [9, 22-24, 26, 27, 29]. Lindsay et al. also found significant decreases in loneliness, however, only in one of the two intervention groups within the study that had used meditative techniques (monitor and acceptance) [25]. Eighteen percent of the studies (2 out of 11) found positive but insignificant decreases in loneliness [30,31]. Jazaieri et al. found improvements in clinical symptoms, such as loneliness, in both its RCT and untreated social anxiety disorder group [33]. It is also important to note that loneliness (and its alleviation) was not measured uniformly across the 11 studies. The following measures were used to "quantify"                      the degree of loneliness: UCLA Loneliness Scale, with variations of the scale used within the studies (n = 8); 6-item de Jong Gierveld Loneliness Scale (DJGLS-6) (n = 1); baseline and post-treatment surveys to measure impacts of intervention (n = 1); and self-reported questionnaire (n = 1). In the 2 remaining (15%) studies, one measured social closeness in lonely individuals, rather than directly evaluating loneliness [28]. The other study attempted to identify the relationship between NF-κB levels and loneliness [32]. These two studies studied loneliness indirectly, thus the direct effect on loneliness was unclear. Overall, these two studies also reported positive findings, with social closeness showing significant improvements, as measured with the inclusion of "other" in a self-scale [28], and the Tai Chi intervention group experiencing a significant decrease in levels of psychological stress, while NF-κB remained unchanged post-intervention using blood samples to measure the NF-κB levels [32].

Relatively small randomized control trials conducted over the last decade
Eight of the 13 (61%) eligible studies were RCTs, 2 out of 13 (15%) were feasibility studies with an RCT design, 1 out of 13 (8%) was a feasibility and acceptability study, 1 out of 13 (8%) was a pilot study looking at feasibility, and  Of the studies with an RCT design, all contained small sample sizes, ranging from 22 to 323 participants, with the definition of small sample size depending upon the individual objectives of each study [34]. Small sample sizes are a limitation, considering that in order to limit biases in the intervention groups, the sample size must be large enough to provide statistical power to detect a clinically meaningful treatment effect [35]. Two out of 8 of the RCT studies (25%) mentioned explicitly that due to their small sample sizes, future replications of the studies with larger sample sizes would be warranted [24,32]. Three out of 8 (37.5%) of the RCT studies made no mention of a small sample size limitation, even though their sample sizes were 153, 323, and 48 participants respectively [25,26,33]. Considering that these three studies created comparisons between two or more groups of subjects, larger studies are needed in order to distinguish between a real effect and random variation [34]. Kok et al. also did not make any mention of having a small sample size (n = 242, after exclusions), however, this may be due to the fact that this trial was embedded within the context of a larger study regarding mental training for healthy adults [28].

Psychosocial factors and age
Forty-six percent (6 out of 13) of the studies were conducted in populations aged 55 and older [9,23,24,26,29,32]. As was noted in many of these studies, loneliness and social isolation are more prevalent in elderly populations, which can lead to numerous negative health outcomes [36].  [32] and have an increased expression of inflammatory genes, which leads to an increased risk of negative health outcomes [9]. Of the six studies focused on older demographics, 33% (2 out of 6) did not provide age-specific information regarding the negative effects of loneliness [24,29]. The negative outcomes seen in the older demographic is due to the fact that older people are likely to live alone and tend to be less socially engaged as a result, leading to what is referred to as a loneliness epidemic [37]. Rodriguez et al. also emphasized that those aged over 64 years are more likely to face loneliness if they live alone [23]. Two other studies (33%) collected demographic data on study participants who lived alone [26,29]. Five out of 6 (83%) of these studies found an improvement in loneliness levels through the use of meditation; the remaining study explored the effects of Tai Chi and meditation on NF-κB signalling in lonely older adults, rather than on loneliness directly [32].

Demographic information
Fifteen percent (2 out of 13) of the studies did not provide information regarding the ethnicities of the included participants. The articles that included this information provided a range of ethnic participants, with one study including all South Asian participants [26] and another including all Hispanic/Spanish individuals [23]. Since the studies included collectively comprised of participants from different regions around the world, studies included domestic participants that reflected the make-up of their countries. However, of these participants, it is unknown how many of them were immigrants and how many are native to their countries. Those that experience migration often have feelings of loneliness, which would have been a factor of importance to explore [38]. Nine out of 13 (69%) of the articles did not provide socioeconomic information indicating the income and class levels of participants, and 3 out of 13 (23%) provided no indication of the education levels of participants. With respect to socioeconomic status, the studies that provided this information did have a range of participants from various classes, though there was an evident lack of lower-class individuals. Only one study had a single participant who earned less than €750 a month [23], while no other study provided any evidence of including participants that fell into the lower-socioeconomic class category. Given that current research evidence indicates that loneliness is associated with health-risk behaviours in deprived neighbourhoods, thereby indicating associations to socioeconomic statuses, the inclusion of participants from these areas would have provided further insight into the effects of meditation for these individuals [39]. This can similarly be said about the education component since one's socioeconomic status can directly correlate to their education level [40]. Most of the studies included participants with some sort of schooling, usually having a minimum of a GED or high school diploma. Only 3 of the 10 studies that provided education information included participants without this qualification, with 2 of the studies including participants with only a primary school education [22,23] and 1 study having a minimum of a pre-high school degree requirement [31]. Overall, within the included studies there was a lack of reporting accounting for the diversity (or lack thereof) comprising the demographic characteristics of included participants.

Discussion
The purpose of the present scoping review was to identify the quantity and type of studies investigating the effects of meditation on loneliness. The available quantity of eligible studies on this topic was relatively small, however, of the 13 eligible studies identified, all reported positive findings. This warrants further research to more comprehensively explore and evaluate the benefits of meditation for those facing loneliness. To our knowledge, this is the first systematicallysearched review to report on this topic; our findings, therefore, provide both healthcare providers and researchers with a greater awareness of the quantity and type of research studies that have been conducted at the intersection of meditation and loneliness.
Loneliness and its effect on meditation is a topic of growing concern; not only has this topic gained more traction due to the growing demographic of aging populations experiencing loneliness, but there is also a public concern about how this demographic will burden the healthcare system and affect public finances [37]. Since loneliness leads to negative health outcomes and is disproportionately seen in the elderly, a focus on how meditation can alleviate loneliness can further reduce the burden on healthcare systems by having these individuals lead more healthy aging lives [36]. With mediation working to alleviate feelings of loneliness, this can result in various positive health outcomes, such as a lower risk for physiological dysregulation and inflammation [18]. Inflammation, specifically, can lead to the development of various diseases that can cause late-life morbidity and mortality, therefore, lowering one's risk of inflammation through the alleviation of loneliness can have significant benefits for one's foreseeable future [9].
It is worth noting that even in many of the ineligible full texts that we had read (but ultimately excluded from this review), social closeness and social isolation were also key focus areas, rather than loneliness, in relation to meditation. Social isolation and loneliness are terms that are often used interchangeably within the literature; we argue that these terms are different, however, as individuals experiencing loneliness may or may not be be socially isolated, and socially isolated people are not always experiencing loneliness [41]. Loneliness is based on how a person feels about their social situation, whereas social isolation is a state regarding one's social situation (i.e. lack of proximity to others). Loneliness also exists in relation to the perceived lack of connectedness felt from interpersonal relationships, which is why social closeness is often a measure of loneliness [41]. Similar to social isolation, social closeness is a state of being around others, though this does not necessarily mean one does or does not feel lonely. The development of a universally agreed-upon definition of loneliness is also warranted to better standardize research aiming to evaluate the value of therapies in alleviating this condition. With this in mind, we have identified a number of warranted directions for future research which could build on the present review's findings.

Areas identified for future research
Relatively small sample sizes were reported across all 13 eligible studies. In line with future directions proposed in some of these eligible studies, a need exists to conduct larger scale research studies to better understand the impacts of meditation on loneliness. Goyal et al. [42] conducted a systematic review and found that meditation programs were useful in reducing psychological stress and showed small improvements for conditions such as anxiety, depression, and pain. However, similar to our scoping review, all of their included studies had small sample sizes ranging from 15 to 201 patients, which supports this identified need for studies including larger sample sizes. Additionally, across all eligible articles, there was no consistent or unified method for measuring participants' degree of loneliness nor its alleviation; instead, we found 4 methods of measurement across the 13 studies. Eight of the 13 articles (61%) utilized the UCLA Loneliness Scale, while other studies used the DJGLS-6 (n = 1) or their own variation of measurement (i.e. baseline and post-treatment surveys, and selfreported questionnaires) (n = 2). Hughes et al. [43] have described the Revised UCLA Loneliness Scale as a long, complex self-administered scale with 20 items and four response categories each. The participant's responses are summed up, and a higher score indicates greater loneliness, making the scale less suitable for telephone surveys in large-scale studies [43]. While this scale is considered to be the most psychometrically sound and most frequently used measure for loneliness, it has been criticized for only measuring the social dimension of loneliness, as opposed to the emotional dimension [44]. In contrast, the Three-Item Loneliness Scale gauges general feelings of loneliness well and can be used across two interview modalities (in-person self-administered and telephone), with the possibility existing for this scale to be embedded within the Revised-UCLA (R-UCLA) itself [43]. In comparison to these methods of measurement, the DJGLS-6 was developed more recently in 2006, taking into account both emotional and social dimensions, but has been less well-evaluated than the R-UCLA [44]. There also appears to be a need to conduct further research that utilizes recently created modes of measurement, such as the DJGLS-6, in order to better evaluate its overall use, reliability, and validity [44]. This could serve to inform the creation of a widely accepted measurement of loneliness that assesses both emotional and social dimensions, which could be used across various interview modalities. Greater knowledge of the specific and targeted benefits (and risks and side effects) of meditation in the context of alleviating loneliness can better assist clinicians in facilitating shared decision making with their patients regarding these interventions [42].
It is also worth noting that the majority of included studies either did not collect or report on the socioeconomic status of their participants (69%). Those that did report it, generally had a lack of study participants identifying as belonging to a lower-socioeconomic class and/or without a high school education, therefore, it is unclear whether findings are applicable to these populations. Thus, a need exists for future studies in this area to include participants from diverse backgrounds in order to account for populations which have been understudied, as such individuals may suffer disproportionately from loneliness.

Strengths and limitations
Notable strengths of this study included the use of a comprehensive systematic search strategy to identify eligible articles. Interpretation of these findings was strengthened by the fact that three authors (GKS, SBH, and ZT) independently screen, data extract, and summarize findings, with assistance from the supervising author (JYN). Limitations include the fact that this scoping review did not include non-English language articles, therefore, studies emerging from non-English speaking countries may not have been captured.

Conclusions
The present scoping review involved a systematic search of the literature to identify the quantity and type of studies investigating the effects of meditation on loneliness. From 13 eligible articles, we identified three major themesincluding: 1) positive results across all studies, 2) relatively small randomized control trials conducted over the last decade, and 3) lack of diverse demographic information. While a small number of studies exist at this intersection, given that all included studies reported positive findings, the effects of meditation in alleviating loneliness are promising. Based on our findings, future studies should consider the use of newer modes of measurement for loneliness, such as the DJGLS-6 and continue to evaluate the utility of meditation in alleviating loneliness; this is especially warranted as the COVID-19 pandemic progresses. Future research should also involve larger sample sizes with a range of participants from various backgrounds and be directed at improving our understanding of how meditation serves to alleviate loneliness. Abbreviations DJGLS-6: 6-Item de Jong Gierveld Loneliness Scale; NF: Nuclear factor; RCT : Randomized control trial; R-UCLA: Revised UCLA.