Table 3 Outcomes and findings of eligible studies

Brooker et al. 2020 [22]

To examine the feasibility and acceptability of an adaptation of the MSC program among adult cancer patients

Acceptability (to clinicians) determined by proportion of clinicians approached who agreed to recruit patients to the study

Feasibility of the mail-out recruitment method was operationalized by the percentage of these clinicians who facilitated a mail-out

Acceptability (to invited patients) determined by the percentage of potential participants who consented to the program, with a target of 10–20%

Acceptability (among those who commenced the program) assessed by retention rates, with 70% target of at least four group session attendance

-Acceptability also measured using a MSC program evaluation form, adapted for cancer context, included in questionnaire after final group session

To examine pre–post-program changes in psychosocial wellbeing: symptoms of depression and stress, fear of cancer recurrence, loneliness, body image, self-compassion, mindfulness

Depression and stress symptoms measured by 21-item Depression Anxiety Stress Scales (DASS-21)

Fear of cancer recurrence or progression measured by 9-item Fear of Cancer Recurrence Inventory-Short Form (FCRI-SF)

Loneliness measured by 20-item UCLA Loneliness Scale Version 3

Body image assessed using 10-item Body Appreciation Scale (BAS) Version 2

Mindfulness measured using Cognitive and Affective Mindfulness Scale-Revised

Positive and negative facets of the three self-compassion components measured using 26-item Self-Compassion Scale (SCS)

Positive:

Feasibility and acceptability: 13 of 17 (76%) of approached clinicians agreed to recruit patients; 19% of contacted patients consented to the program—in total, 32 participants consented to the program, with 30 commencing it and 27 completing it

Results of Intervention: Significant decrease in loneliness (medium to large effect), depression (large effect), stress (medium to large effect), and fear of cancer recurrence (medium to large effect) in intervention group. Significant increase in mindfulness (large effect)

Nonsignificant increase in body appreciation (small to medium effect) and self-compassion (medium to large effect)

Study Design: Study did not include a control arm and had a small sample size, making it difficult to attribute pre- to post-intervention changes to intervention. Study had a small sample size

Program Length: Shortened version of the program was delivered (14 vs 20 h) which may have accounted for smaller effect sizes

Recruitment Strategy: Patients were invited to participate by treating clinicians, which may have elevated perceived acceptability compared to other channels

The adaptation of an 8-week mindfulness and self-compassion program for patients with non-advanced cancer diagnosis is feasible and acceptable. Preliminary findings indicate that the intervention has significant increases in psychosocial well-being and loneliness. However, additional studies with a control group must be undertaken to validate results

Rodriguez-Romero et al. 2020 [23]

Loneliness, social support, depression, and quality of life (physical and mental)

Perceived loneliness assessed by the UCLA scale

Degree of autonomy measured by the Barthel Index

Degree of cognitive impairment assessed by the Pfeiffer test

Depressive symptoms using the Yesavage abbreviated questionnaire

Perceived social support evaluated by the Duke-UNC-11 Functional Social Support Questionnaire

Perceived quality of life measured by the 12-Item Short Form Health Survey (SF-12)

Group sessions assessed by intervention group participants using a satisfaction survey at the end of the programme

Sessional attendance collected using a weekly attendance record

Not available

Not applicable

Positive:

Improvements in all measures except for the SF-12 (quality of life) physical component

-Significant improvement in degree of loneliness within the intervention group, with no perceived loneliness shown at 6 months by 14 (48.3%) participants

Nonsignificant increase in control group patients with severe loneliness at 6 months (7.7% preintervention vs. 19.2% postintervention)

Mean improvement in degree of loneliness was 8.63 points (95% CI 1.97–15.30) higher in the intervention group in comparison to the control group (p = 0.012)

Small sample size: Of the 80 referred patients, 25 were excluded since 6 were unavailable throughout the study, 6 didn't experience loneliness, 6 didn't attend sessions due to caring for a relative 24 h a day, 6 didn't have enough time, and 1 refused to participate. It is hard to recruit lonely people, as seen through the small sample size, which suggests that the community intervention reached primarily people with moderate loneliness; not those with severe loneliness, who might benefit from a more personalised approach

Study design: Did not allow for measurement of the intervention benefits over time due to a lack of follow-up once the intervention was complete

After participating in a community intervention promoting socialisation, almost half of the lonely older persons stopped feeling lonely and their health status improved. During this same period of time, controls with a similar baseline showed no change in their perception of loneliness or other health variables. These results are similar to the findings in other studies, however, a smaller decrease in loneliness is seen in studies of individual interventions

Lee et al. 2019 [24]

Whether BEM affects the conditions of patients with hypertension and/or type 2 diabetes compared with health education classes (Mental/physical health and wellbeing: relaxation, focus, happiness, confidence, reduction in anger, loneliness)

Blood collection, followed by measurement of serum glutamic-oxaloacetic transaminase, serum glutamic pyruvic transaminase, γ-glutamyl transferase, creatinine, high-density lipoprotein cholesterol, and low-density lipoprotein (LDL) cholesterol

Ribonucleic acid (RNA) extraction, complementary deoxyribonucleic acid synthesis and reverse transcription polymerase chain reaction of inflammatory genes

Self-reported questionnaires of mental and physical health of 20 items with a 5-point Likert-type scale for each response

Not available

Not applicable

Positive:

Intervention (BEM) group showed significant decreases in LDL cholesterol post-intervention, while control group did not. Intervention group also had significant reductions in expression of inflammatory genes

Mental and Physical Health: Post-intervention self-report scores for the intervention group showcase significant increases in focus, confidence, relaxation and happiness, along with significant decreases in fatigue, anger and loneliness

There were no important adverse events or side-effects by BEM intervention

Study Design: Relatively small sample size (follow-up with a larger sample needed to validate findings). Intervention (BEM) included both static and dynamic elements making it difficult to know which elements contributed to which results. More measurements required such as hemoglobin A1c and body mass index (BMI)

Other Factors Responsible for Effects: Medication types were not controlled for, therefore some of the medication taken by participants may have impacted results

The results of the pilot-randomized controlled trail showcase that a BEM intervention reduces LDL cholesterol and inflammatory gene expression, in addition to improving mental and physical health in patients with type 2 diabetes/hypertension, compared to health education. Since both type 2 diabetes and hypertension are chronic conditions, positive effects from non-invasive interventions such as BEM are significant for long-term complementary care

Lindsay et al. 2019 [25]

Assessing loneliness and social isolation/social interaction in participants’ natural environments, as well as global retrospective measures of loneliness and social support. Social Processes (subjective perception of loneliness, objective number of social interaction and partners)

Social processes measured by Ecological Momentary Assessment, carried out 4 quasi-random times a day, and End-of-Day Surveys

Retrospective loneliness measured by UCLA Loneliness Scale

Retrospective social isolation measured by Social Network Index

Retrospective social support measured by Interpersonal Support Evaluation List

Reactions to social interactions were measured using a subset of Ecological Momentary Survey

Not available

Not applicable

Positive Outcome for Some Interventions:

Patients undergoing monitor and acceptance mindfulness meditation training showed significant decreases in loneliness and significant increases in social interactions pre- to post-intervention. In contrast, patients in the monitor only or control group did not showcase any significant differences in loneliness and social interactions pre- to post-intervention

Overall, monitor and acceptance training reduced daily-life loneliness by 22%, and increased social interactions by 2 more interactions per day and one more person per day compared to monitor only or control training

Study Design: Sampling (Recruited a sample of stressed community adults rather than specifically targeting socially isolated individuals) and follow-up (no follow-up included in study)

Further research is needed to test whether smartphone-based mindfulness meditation training can reduce loneliness within lonely population

Further research is also needed to identify whether mindfulness training helps strengthen current relationships or aids in the formation of new relationships

This 2-week trial provides evidence that individually delivered smartphone-based mindfulness training can reduce loneliness and increase social contact in daily life. Importantly, the differences between intervention groups showcased the importance of developing an accepting attitude towards present experiences in order to decrease loneliness and improve social contact

Pandya 2019 [26]

Loneliness, Well-Being, Life Satisfaction, Contentment with Life

6-Item de Jong Gierveld Loneliness Scale

Warwick-Edinburgh Mental Wellbeing Scale

5-Item Satisfaction with Life Scale (SWLS)

Contentment with Life Assessment Scale

Not available

Not applicable

Positive:

Pre-Intervention: There were no significant differences in psychosocial measures within the intervention and control group at baseline

Post-Intervention: No significant increases in measures for control group. In contrast, the intervention group showed a significant decrease in loneliness, significant increase in mental well-being, satisfaction with life, and contentment with life. Furthermore, all post-intervention outcome measures for the invention group were higher than for the control group

Study Design: Data was only gathered at 2 specific time points, which does not account for interim changes. No qualitative data was collected to study perceptions of intervention. Self-practice was an important predictor for success, but variances in conditions for self-practice were not tracked or controlled

Sampling and Study Population: Study population had a lot of heterogeneity, mostly compromising middle-class married Hindu men

A customized meditation program can significantly alleviate loneliness in older adults. It may be customized and refined for different demographics such as women, upper class individuals, single vs married, living alone vs cohabiting with family, Buddhists, and those with congenital chronic ailments. Loneliness-mitigation is through building older participants’ inner resources rather than networks and social skills. Program impact is dependent on regular attendance and home practice

Mascaro et al. 2018 [27]

(1) investigate the feasibility of CBCT for second-year medical students, and (2) test whether CBCT decreases depression, enhances compassion, and improves daily functioning in medical students. (3) who benefited most from compassion meditation by testing the hypothesis that CBCT would have the greatest impact on compassion among those suffering from depression, stress, and anxiety

Digital or paper self-report questionnaires pre and post intervention

Interpersonal health measured using Compassionate Love for Humanity Scale

UCLA Loneliness Scale (R-UCLA)

Sleep quality assessed using Pittsburgh Sleep Scale

Quantity and frequency of substance use such as tobacco, marijuana, alcohol, or prescription drugs, measured using Substance Use Inventory

Negative emotions measured using DASS

Frequency of physical and aerobic exercise over the past month measured by asking two questions as part of assessment

Not available

Not applicable

Positive:

Individuals randomized to CBCT intervention reported significant decrease in depression and loneliness, along with an increase in compassion and less exercise post-intervention. There were no significant changes in the wait-list control group post-intervention

Furthermore, there was a significant main effect of time in the CBCT intervention group for increases in compassionate love and sleep, and decreases in loneliness, depression and exercise

Sample size: Small

Other non-specific factors may have influenced outcomes

Study does not provide significant insight into the complex nature of socio-cognitive changes that may result from CBCT or how they may alter physician competence or patient outcomes

The study's findings indicate that CBCT may be beneficial for enhancing compassion and reducing depression and loneliness for medical students. Further studies are needed to study mechanisms of the CBCT effect, along with its long-term effects and impacts of patient outcomes

Kok et al. 2017 [28]

Self-disclosure and social closeness

Engagement Measures (compliance, liking, motivation to practice)

Outcome Measures (Closeness of dyadic partner, self-disclosure)

Compliance measured through ranked scale reporting of motivation and liking

Closeness measured with Inclusion of Other in the Self Scale

Self-disclosure using Ranked Scale for Self-Disclosure Rating

Valence and arousal

Valence and arousal assessed before and after all sessions, assessing affect with scales using ranges of 0 to 8

Positive:

All participants practiced breathing meditation and body scans (presence modules), followed by dyadic practice (affect module and perspective module). Compliance was similar across all modules, while motivation was higher for the meditation modules

Social closeness showed significant improvements during a session for the affect dyads and significant increase over time for the affect dyad. Self-disclosure increased over time for the affect dyad and the perspective dyad, with the perspective dyad showcasing a greater rate of increase (both significant results)

Study Design: Trial of contemplative dyads was embedded with a larger mental training study; therefore, the effects of contemplative dyads on social closeness and self-disclosure needs to be studied independently

Study Population: Included only health adults; further research with populations at greater risk of suffering from loneliness, such as older adults or adults with maladaptive social cognitions, is needed

In this trial, 2 types of contemplative dyadic exercises practiced over 6 months increased social closeness and self-disclosure among participants. Provides evidence for new type of intervention targeting social connection in individuals who may suffer from loneliness

Tkatch et al. 2017 [29]

To determine if this intervention could be a feasible approach for this population (community-dwelling older adult caregivers). Feasibility was initially assessed by the ability to attract participants and sustain engagement in the intervention

Attendance of the weekly (online and in-person) modules was recorded

Impact of the intervention on caregiver burden, quality of life (mental and physical well-being), and psychological well-being measures, including stress, loneliness, anxiety, and social support

Baseline and post-treatment surveys measured the impact of the intervention, such as caregiver burden, quality of life, psychological well-being measures such as loneliness, stress, anxiety, social support

Caregiver burden measured by Zarit Short Burden Interview

12-item Veteran’s Rand

4-item Perceived Stress Scale

7-item Generalized Anxiety Disorder Test

3-item UCLA Loneliness Scale

12-item Interpersonal Support Evaluation List

Positive:

Post-intervention, participants had significant decreases in caregiver burden, stress, loneliness, and anxiety, and significant increases in mental health

Higher levels of session attendance was significantly associated with positive changes in perceived social support and the mental component score, along with significant decreases in stress and anxiety

Study Design: No control group and small sample size

Study Population: Participants were recruited from an existing caregiver support group and therefore, might have a greater need for support and a willingness to participate, decreasing generalizability to all caregivers

This pilot study provides evidence that online mindfulness meditation programs have the potential to significantly reduce caregiver burden, along with improving mental health for older caregivers. Future studies could expand on results by testing with a larger sample size and longitudinal cohorts or targeting caregivers of older adults with special needs or young children

Dodds et al. 2015 [30]

The feasibility of a meditation-based program (CBCT) with breast cancer survivors treated with systemic adjuvant chemotherapy within past 10 years

Recruitment rate

Screening and enrollment rate

Class attendance

Adherence

Retention

Participant satisfaction and interest

The impact of CBCT on behavioural endpoints (Perceptions of Loneliness and Social Connectedness, Perceived Stress, Depression, Psychological Distress and Functioning Impairments linked to fear of cancer recurrence, Intrusive Thoughts, Avoidance and Hyperarousal, Pain and Vitality, Global Attention, Awareness, Present Focus and Acceptance, Gratitude, Satisfaction)

Diurnal rhythm of cortisol (a stress-related endocrine biomarker)

Impact of home practice on outcomes (Adherence to CBCT Protocol)

Salivary cortisol collection through at-home collection kits

4-item Perceived Stress Scale (PSS-4)

Brief Center for Epidemiologic Studies—Depression questionnaire

Five subscales of the FCRI

Impact of Events Scale—Revised

R-UCLA Version 3

Medical Outcomes Study SF-12

Cognitive and Affective Mindfulness Scale—Revised

Gratitude Questionnaire—6, participant satisfaction measured by two items

Positive: Positive but non-significant findings in relation to loneliness

Feasibility and Acceptance: Attendance and participant satisfaction met the pre-defined criteria, while retention, home meditation practice days and recruitment rate were slightly under goals

Behavioural and Psychosocial Outcomes: Significant decreases in depressive symptoms, functional impairments from fear of cancer recurrence, avoidance were observed pre- to post-intervention, in addition to a significant increase in mindful presence

Loneliness: Nonsignificant decrease in loneliness post-intervention and at 1-month follow-up

Cortisol: No effect of CBCT was observed on any measure of cortisol (including diurnal cortisol rhythm)

Recruitment Rate: Lower than planned, with a bias towards participants with higher. socioeconomic status

Potential Bias: Potential positive impact of self-reporting problems commonly experienced during survivorship

Data Collection: 3 Participants did not return practice log data at follow-up period

Effects of Intervention: Possible ceiling effect with participants engaging in at-home meditation practice to the point where a positive correlation is less likely to be seen

Within the limits of a pilot feasibility study, results suggest that CBCT is a feasible and highly satisfactory intervention potentially beneficial to the psychological well-being of breast cancer survivors. However, more comprehensive trials are needed to provide systematic evidence

Samhkaniyan et al. 2015 [31]

The performance of mindfulness according to the cognitive approach on the quality of life and loneliness of women with HIV

Quality of life survey from WHO and revised UCLA to both groups pre and post intervention

Not available

Not applicable

Positive:

MBCT resulted in increases in mean quality of life and non-significant decreases in loneliness (when comparing pre- and post-intervention scores within the intervention group only, and between intervention and control group)

Sample Size: Small sample size, which could minimize generalizability and significance of results

No similar studies in Iran to validate/compare conclusions to

This study provides evidence that group based MBCT is effective in reducing loneliness and increasing the quality of life in women with HIV

Black et al. 2014 [32]

Affect of TCC on psychologic stress and NF-κB levels in lonely older adults, as compared to those who receive a stress and health education (SHE) intervention

14-Item PSS

Blood sample collection and measurement of serum nuclear factor (NF)-kB

Not available

Not applicable

Unclear/Positive Findings:

In the health education control group, psychological stress levels were unchanged, while nuclear levels of activated NF-κB significantly increase post-intervention

In the Tai Chi intervention group, levels of psychological stress significantly decreased, while NF-κB levels remained unchanged post-intervention

Study Population: Small sample size consisting predominantly of women, limiting generalizability of results

Lack of Measurements: NF-κB levels were only measured in peripheral blood mononuclear cells (PBMCs); therefore, observed changes may be due to changes in lymphocyte subset distribution

TCC significantly reduced levels of psychological stress compared to the control group, while attenuating the rise of NF-κB activation in lonely older adults

Creswell et al. 2012 [9]

Effects of MBSR on loneliness and loneliness-related inflammatory genes such as NF-kB

Perceived loneliness assessed by the UCLA scale, revised (UCLA-R) at baseline and post-treatment

Blood sample collection and RNA extracted from PBMCs

Mindfulness measured using 39-item Kentucky Inventory of Mindfulness Skills

Bioinformatic indications of increased expression of pro-inflammatory genes like NF-kB transcription factor, monocyte-mediated gene expression (while controlling for sex, age, ethnicity, and BMI)

Different white blood cell subtypes of gene expression changes determined using transcript origin analysis

C-reactive protein and interleukin-6 levels measured in EDTA samples by high sensitivity ELISA

Effects of MSBR on self-reported sleep quality and exercise

-Sleep quality measured using Pittsburgh Sleep Quality Index measure

-Self-reported exercise

Positive:

MBSR intervention group showcase a significant decrease in loneliness post-intervention, compared to a small decrease in the wait-list control group. Similarly, after controlling for baseline loneliness, MBSR intervention group had significantly lower loneliness scores post-intervention than control

MBSR intervention group also had significant reductions in activity of NF-κB target genes post-intervention compared to control group

No significant effect of intervention on sleep quality was observed

Study Design: Wait list control group instead of an active comparator arm

Intervention Design: Mindfulness meditation was taught in groups instead of individually. Teaching it individually may have shown an increased effect

The study provides evidence that an 8-week MBSR intervention reduces perceptions of loneliness in older adults. Evidence also supports that loneliness is associated with increased activity of NF-κB target genes and that MBSR can significantly downregulate this gene expression in parallel to loneliness reduction

Jazaieri et al. 2012 [33]

Many factors (i.e. clinical symptoms and subjective well-being) measured such as social interactions, loneliness, depressive symptoms, social anxiety, psychological stress, self-esteem, life satisfaction, self-compassion

Liebowitz Social Anxiety Scale-Self-Report

Social Interaction Anxiety Scale Straightforward Scale

Beck Depression Inventory-II

PSS-4

Rosenberg Self-Esteem Scale

SWLS

SCS, UCLA-8 Loneliness Scale

Not available

Not applicable

Positive:

Both MBSR and aerobic exercise (AE) were linked to a reduction in social anxiety and depression, as well as an increase in subjective well-being. Overall, no significant differences in these measures were seen between MBSR and AE

Participants in both the randomized controlled trial and the untreated social anxiety disorder (SAD) group showed improvements in their measures of clinical symptoms and well-being

Study Design: The respective group experiences and time entailed in each interaction may be the cause for the apparent differences between the intervention groups

Sampling: Study required participants to voluntarily contact researchers to partake in the study, which may have resulted in a study population with less severe social anxiety

Non-traditional interventions such as MBSR and AE produce modest clinically significant changes in social anxiety, depression, and subjective well-being for patients with SAD. However, these changes were not at the same level as what has been found in previous studies with traditional treatments