Social isolation as a risk factor for all-cause mortality: Systematic review and meta-analysis of cohort studies

Association between the level of social participation and depressive symptoms among older Japanese adults: a cross-sectional survey

BACKGROUND

Social participation is recommended for older adults to remain actively involved in daily life. Social participation is a broad concept, ranging from 'interacting with others without doing a specific activity with them' to 'actively contributing to society.' However, previous studies have not taken into account the components of social participation. Depressive symptoms are significant outcomes in older adults. Social participation mitigates these risks owing to its association with reduced mortality and enhanced quality of life. This study aimed to examine the association between the level of social participation and depressive symptoms in community-dwelling older adults.

METHODS

We included 17 040 individuals aged ≥65 years. Social participation was categorised into Level 3, interacting with others without doing a specific activity with them; Level 4, engaging in an activity with others; Level 5, helping others; and Level 6, contributing to society, based on a previous study by Levasseur et al. Depressive symptoms were assessed using the 15-item Geriatric Depression Scale. Logistic regression models were used to examine the association between the level of social participation and depressive symptoms.

RESULTS

Overall, 15 069 older adults met the inclusion criteria. A higher level of social participation was associated with lower odds ratios (ORs) for depressive symptoms (Level 6 = OR: 0.43, 95% confidence interval (CI): 0.37-0.50; Level 5 = OR: 0.50, 95% CI: 0.41-0.60; and Level 4 = OR: 0.60, 95% CI: 0.52-0.69). Subgroup analyses based on age and sex yielded similar results across all participants.

CONCLUSIONS

Among older adults in Japan, a higher level of social participation was associated with lower rates of depressive symptoms. The relationship between depressive symptoms and the levels of social participation may help develop measures to reduce or prevent depressive symptoms in older adults.

Impact of social isolation on corticosterone release and recovery after stroke in aged rats: A behavioral and biochemical analysis

Social isolation (SI) after stroke reduces recovery. The aim of this study was to evaluate the effects of SI on corticosterone release and recovery after stroke in aged rats. A total of 64 male Wistar rats (aged 24 months) were used in the present study. All rats were housed in pairs for two weeks. After two weeks, rats were randomly assigned to one of four groups: (1) rats underwent sham surgery and kept socially isolated (control/social isolated (CO/SI) group); (2) rats underwent sham surgery and kept pair housed (control/pair housed (CO/PH) group); (3) rats underwent middle cerebral artery occlusion (MCAO) surgery and kept socially isolated (stroke/isolated (ST/SI) group); (4) rats underwent MCAO surgery and kept pair housed (stroke/pair housed (ST/PH)) group. Behaviors were assessed using the adhesive removal test, rotarod test and social interaction test at 1st, 7th, 14th and 21st days after stroke. Serum biochemical analysis was also performed on the behavioral testing days. Results showed THAT serum corticosterone and MDA levels in CO/PH group were significantly lower than CO/SI group. Serum BDNF levels in CO/PH group was significantly higher than CO/SI group. Serum corticosterone and MDA levels in ST/PH group were lower than ST/SI group. In ST/PH group, serum Total antioxidant capacity (TAC) and BDNF levels were significantly higher than ST/SI group. Biochemical analysis of certain regions of the brain (hippocampus, striatum and cerebral cortex) was performed on 21st day after stroke. In the hippocampus of CO/PH group, BDNF and TAC levels were significantly higher than CO/SI group. The hippocampal MDA level of CO/PH group were significantly lower than CO/SI group. BDNF and TAC levels in the hippocampus, striatum and cerebral cortex of ST/PH group were significantly higher and MDA level was significantly lower as compared with ST/SI group. Both ischemic groups showed sensorimotor recovery over a 21-day period, but recovery of ST/PH group was significantly greater than ST/SI group. Total social interaction time in ST/PH group was significantly longer than ST/SI group. Based on the results of this study, social interaction after stroke enhances histologic and sensorimotor recovery through reduction of HPA activity and corticosterone release, leading to increased TAC and BDNF levels.

Development and validation of a social alienation predictive model for older maintenance hemodialysis patients based on latent profile analysis-a cross-sectional study

BACKGROUND

Social alienation refers to the state of feeling isolated, helpless, and unsatisfied due to maintaining distance from others or avoiding social interaction and activities. This phenomenon is caused by a lack of social skills, social anxiety, physical health problems, and other reasons. Older maintenance hemodialysis patients are exposed to a higher risk of social alienation. However, previous studies have been performed using the total score of the scale, which does not allow the identification of the characteristics of various patient groups with different levels of social alienation. In contrast, latent profile analysis can classify individuals into different categories based on continuous observational indicators, which improves accuracy and provides a more objective assessment by accounting for the uncertainty of variables. Given the concealed nature of social alienation and the differences in characteristics and treatment measures between different profiles, developing a predictive model for social alienation in older maintenance hemodialysis patients holds significance.

OBJECTIVE

To explore the latent profile analysis of social alienation in older maintenance hemodialysis patients and to develop and validate a predictive model for social alienation in this population.

METHODS

A total of 350 older maintenance hemodialysis patients were selected as the study subjects using convenience sampling. A cross-sectional survey was conducted using a general information questionnaire, the Generalized Alienation Scale, and the Self-Perceived Burden Scale. Based on the results of the Generalized Alienation Scale, a latent profile analysis was performed, followed by univariate analysis and multinomial logistic regression to develop a predictive model. The effectiveness of the predictive model was evaluated in terms of its authenticity, reliability, and predictive ability.

RESULTS

Three hundred nineteen valid questionnaires were collected. The social alienation of older maintenance hemodialysis patients based on latent profile analysis were divided into three profiles, which were named the low/medium/high-symptom groups, comprising 21%, 38.9%, and 40.1% of participants, respectively. Based on male, monthly social activity hours, Age-Adjusted Charlson Comorbidity Index, dialysis age, and Self-Perceived Burden Scale, a predictive model of social alienation for older maintenance hemodialysis patients was developed, and the Hosmer-Lemeshow tests showed no statistical significance (P > 0.05). The model has high predictive efficiency in authenticity, reliability and predictability.

CONCLUSION

Older maintenance hemodialysis patients exhibited moderate to high levels of social alienation. The latent profile analysis based method was used to divide patients into low/medium/high-symptom profiles, and the predictive model demonstrates excellent authenticity, reliability, and predictability.

Use of social network analysis in health research: a scoping review protocol

INTRODUCTION

Social networks can affect health beliefs, behaviours and outcomes through various mechanisms, including social support, social influence and information diffusion. Social network analysis (SNA), an approach which emerged from the relational perspective in social theory, has been increasingly used in health research. This paper outlines the protocol for a scoping review of literature that uses social network analytical tools to examine the effects of social connections on individual non-communicable disease and health outcomes.

METHODS AND ANALYSIS

This scoping review will be guided by Arksey and O'Malley's framework for conducting scoping reviews. A search of the electronic databases, Ovid Medline, PsycINFO, EMBASE and CINAHL, will be conducted in April 2024 using terms related to SNA. Two reviewers will independently assess the titles and abstracts, then the full text, of identified studies to determine whether they meet inclusion criteria. Studies that use SNA as a tool to examine the effects of social networks on individual physical health, mental health, well-being, health behaviours, healthcare utilisation, or health-related engagement, knowledge, or trust will be included. Studies examining communicable disease prevention, transmission or outcomes will be excluded. Two reviewers will extract data from the included studies. Data will be presented in tables and figures, along with a narrative synthesis.

ETHICS AND DISSEMINATION

This scoping review will synthesise data from articles published in peer-reviewed journals. The results of this review will map the ways in which SNA has been used in non-communicable disease health research. It will identify areas of health research where SNA has been heavily used and where future systematic reviews may be needed, as well as areas of opportunity where SNA remains a lesser-used method in exploring the relationship between social connections and health outcomes.

Sociodemographic Heterogeneity in the Associations of Social Isolation With Mortality

Importance

There are limited data on whether the vulnerabilities and impacts of social isolation vary across populations.

Objective

To explore the association between social isolation and mortality due to all causes, cardiovascular diseases (CVD), and malignant neoplasms focusing on heterogeneity by sociodemographic factors.

Design, Setting, and Participants

This cohort study used a moderator-wide approach to examine the heterogeneity in the association of social isolation with all-cause, CVD, and malignant neoplasm mortality using baseline data from the Japan Gerontological Evaluation Study in 2010 and 2011. Eligible participants were adults aged 65 years or older without heart disease, stroke, cancer, or impaired activity of daily living across 12 Japanese municipalities. Follow-up continued until December 31, 2017, identifying 6-year all-cause, cardiovascular disease (CVD), and malignant neoplasm mortality. Logistic regression assessed effect modification by age, gender, education, income, population density, marital status, and employment on mortality associations. Data analysis was performed from September 13, 2023, to March 17, 2024.

Exposure

Social isolation, determined by a 3-item scale (scores of 2 or 3 indicating isolation) was the primary exposure variable.

Main Outcomes and Measures

Six-year all-cause, CVD, and malignant neoplasms mortality.

Results

This study included 37 604 older adults, with a mean (SD) age of 73.5 (5.9) years (21 073 women [56.0%]). A total of 10 094 participants (26.8%) were classified as experiencing social isolation. Social isolation was associated with increased all-cause (odds ratio [OR], 1.20 [95% CI, 1.09-1.32]), CVD (OR, 1.22 [95% CI, 0.98-1.52]), and malignant neoplasm mortality (OR, 1.14 [95% CI, 1.01-1.28]). Stratified analysis showed associations of social isolation with all-cause and malignant neoplasm mortality among people with high income (highest tertile all cause: OR, 1.27 [95% CI, 1.06-1.53]; malignant neoplasm: OR, 1.27 [95% CI, 1.02-1.60]), living in areas with high population density (highest tertile all cause: OR, 1.47 [95% CI, 1.26-1.72]; malignant neoplasm: OR, 1.38 [95% CI, 1.11-1.70]), not married (all cause: OR, 1.33 [95% CI, 1.15-1.53]; malignant neoplasm: OR, 1.25 [95% CI, 1.02-1.52]), and retirees (all cause: OR, 1.27 [95% CI, 1.14-1.43]; malignant neoplasm: OR, 1.27 [95% CI, 1.10-1.48]). Formal testing for effect modification indicated modification by population density and employment for all-cause mortality and by household income and employment for neoplasm mortality.

Conclusions and Relevance

Social isolation was associated with increased risks of all-cause, CVD, and malignant neoplasm mortality, with associations varying across populations. This study fills an important gap in research on social isolation, emphasizing its varied associations across demographic and socioeconomic groups.

A deathly silence: why has the number of people found decomposed in England and Wales been rising?

OBJECTIVES

The number of deaths occurring in private homes in England and Wales had been rising for years, increasingly rapidly from 2020. Media stories and research linked decomposing bodies found in private homes with pandemic-related social isolation. We aim to explore whether these incidents are one-offs or part of a wider trend.

DESIGN

Descriptive analysis of publicly available Office for National Statistics (ONS) data.

SETTING

England and Wales.

PARTICIPANTS

All residents of England and Wales, 1979 to 2020.

MAIN OUTCOME MEASURES

Using data from the Office for National Statistics, we calculate European Age Standardised Rates for deaths coded as R98 ('unattended death') and R99 ('other ill-defined and unknown causes of mortality') in the 10th version of the International Classification of Diseases (ICD-10), and the corresponding codes in ICD-9, by sex and age group from 1979 (when ICD-9 began) to 2020. These are proxy markers for deaths where decomposition precludes attribution of a specific cause at postmortem.

RESULTS

While mortality from all other causes decreased from 1979 to 2020, the opposite was seen for deaths from R98 and R99 (or 'undefined deaths'), with men more affected than women. There was a sharp rise in these deaths in both sexes but in men particularly in the 1990s and 2000s, coinciding with a time when overall mortality was rapidly improving.

CONCLUSIONS

The increase in people found dead from unknown causes suggests wider societal breakdowns of both formal and informal social support networks. They are concerning and warrant urgent further investigation. We call on national and international authorities to consider measures that would make it possible to identify these deaths more easily in routine data.

The protective effect of social support on all-cause and cardio-cerebrovascular mortality among middle-aged and older adults in the US

The relationship between social support and mortality, especially cardio-cerebrovascular mortality, still has some limitations in the assessment of social support, sample selection bias, and short follow-up time. We used the data from 2005 to 2008 National Health and Nutrition Examination Survey to examine this relationship. The study analyzed a total of 6776 participants, divided into Group 1, Group 2, and Group 3 according to the social support score (0-1; 2-3; 4-5). Multivariable adjusted COX regression analyses of our study showed that Group 3 and Group 2 had a reduced risk of all-cause and cardio-cerebrovascular mortality (Group 3 vs 1, HR: 0.55, P < 0.001; HR: 0.4, P < 0.001; Group 2 vs 1, HR: 0.77, P = 0.017; HR: 0.58, P = 0.014) compared with Group 1. The same results were observed after excluding those who died in a relatively short time. Additionally, having more close friends, being married or living as married, and enough attending religious services were significantly related to a lower risk of mortality after adjustment. In brief, adequate social support is beneficial in reducing the risk of all-cause mortality and cardio-cerebrovascular mortality in middle-aged and older adults, especially in terms of attending religious services frequency, the number of close friends, and marital status.

Lessons from lonely flies: Molecular and neuronal mechanisms underlying social isolation

Animals respond to changes in the environment which affect their internal state by adapting their behaviors. Social isolation is a form of passive environmental stressor that alters behaviors across animal kingdom, including humans, rodents, and fruit flies. Social isolation is known to increase violence, disrupt sleep and increase depression leading to poor mental and physical health. Recent evidences from several model organisms suggest that social isolation leads to remodeling of the transcriptional and epigenetic landscape which alters behavioral outcomes. In this review, we explore how manipulating social experience of fruit fly Drosophila melanogaster can shed light on molecular and neuronal mechanisms underlying isolation driven behaviors. We discuss the recent advances made using the powerful genetic toolkit and behavioral assays in Drosophila to uncover role of neuromodulators, sensory modalities, pheromones, neuronal circuits and molecular mechanisms in mediating social isolation. The insights gained from these studies could be crucial for developing effective therapeutic interventions in future.

Social connection and mortality in UK Biobank: a prospective cohort analysis

BACKGROUND

Components of social connection are associated with mortality, but research examining their independent and combined effects in the same dataset is lacking. This study aimed to examine the independent and combined associations between functional and structural components of social connection and mortality.

METHODS

Analysis of 458,146 participants with full data from the UK Biobank cohort linked to mortality registers. Social connection was assessed using two functional (frequency of ability to confide in someone close and often feeling lonely) and three structural (frequency of friends/family visits, weekly group activities, and living alone) component measures. Cox proportional hazard models were used to examine the associations with all-cause and cardiovascular disease (CVD) mortality.

RESULTS

Over a median of 12.6 years (IQR 11.9-13.3) follow-up, 33,135 (7.2%) participants died, including 5112 (1.1%) CVD deaths. All social connection measures were independently associated with both outcomes. Friends/family visit frequencies < monthly were associated with a higher risk of mortality indicating a threshold effect. There were interactions between living alone and friends/family visits and between living alone and weekly group activity. For example, compared with daily friends/family visits-not living alone, there was higher all-cause mortality for daily visits-living alone (HR 1.19 [95% CI 1.12-1.26]), for never having visits-not living alone (1.33 [1.22-1.46]), and for never having visits-living alone (1.77 [1.61-1.95]). Never having friends/family visits whilst living alone potentially counteracted benefits from other components as mortality risks were highest for those reporting both never having visits and living alone regardless of weekly group activity or functional components. When all measures were combined into overall functional and structural components, there was an interaction between components: compared with participants defined as not isolated by both components, those considered isolated by both components had higher CVD mortality (HR 1.63 [1.51-1.76]) than each component alone (functional isolation 1.17 [1.06-1.29]; structural isolation 1.27 [1.18-1.36]).

CONCLUSIONS

This work suggests (1) a potential threshold effect for friends/family visits, (2) that those who live alone with additional concurrent markers of structural isolation may represent a high-risk population, (3) that beneficial associations for some types of social connection might not be felt when other types of social connection are absent, and (4) considering both functional and structural components of social connection may help to identify the most isolated in society.

Digitally Enabled Peer Support Intervention to Address Loneliness and Mental Health: Prospective Cohort Analysis

BACKGROUND

Social isolation and loneliness affect 61% of US adults and are associated with significant increases in excessive mental and physical morbidity and mortality. Annual health care spending is US $1643 higher for socially isolated individuals than for those not socially isolated.

OBJECTIVE

We prospectively evaluated the effects of participation with a digitally enabled peer support intervention on loneliness, depression, anxiety, and health-related quality of life among adults with loneliness.

METHODS

Adults aged 18 years and older living in Colorado were recruited to participate in a peer support program via social media campaigns. The intervention included peer support, group coaching, the ability to become a peer helper, and referral to other behavioral health resources. Participants were asked to complete surveys at baseline, 30, 60, and 90 days, which included questions from the validated University of California, Los Angeles Loneliness Scale, Patient Health Questionnaire 2-Item Scale, General Anxiety Disorder 7-Item Scale, and a 2-item measure assessing unhealthy days due to physical condition and mental condition. A growth curve modeling procedure using multilevel regression analyses was conducted to test for linear changes in the outcome variables from baseline to the end of the intervention.

RESULTS

In total, 815 ethnically and socially diverse participants completed registration (mean age 38, SD 12.7; range 18-70 years; female: n=310, 38%; White: n=438, 53.7%; Hispanic: n=133, 16.3%; Black: n=51, 6.3%; n=263, 56.1% had a high social vulnerability score). Participants most commonly joined the following peer communities: loneliness (n=220, 27%), building self-esteem (n=187, 23%), coping with depression (n=179, 22%), and anxiety (n=114, 14%). Program engagement was high, with 90% (n=733) engaged with the platform at 60 days and 86% (n=701) at 90 days. There was a statistically (P<.001 for all outcomes) and clinically significant improvement in all clinical outcomes of interest: a 14.6% (mean 6.47) decrease in loneliness at 90 days; a 50.1% (mean 1.89) decline in depression symptoms at 90 days; a 29% (mean 1.42) reduction in anxiety symptoms at 90 days; and a 13% (mean 21.35) improvement in health-related quality of life at 90 days. Based on changes in health-related quality of life, we estimated a reduction in annual medical costs of US $615 per participant. The program was successful in referring participants to behavioral health educational resources, with 27% (n=217) of participants accessing a resource about how to best support those experiencing psychological distress and 15% (n=45) of women accessing a program about the risks of excessive alcohol use.

CONCLUSIONS

Our results suggest that a digitally enabled peer support program can be effective in addressing loneliness, depression, anxiety, and health-related quality of life among a diverse population of adults with loneliness. Moreover, it holds promise as a tool for identifying and referring members to relevant behavioral health resources.