The association between loneliness, social isolation and inflammation: A systematic review and meta-analysis

HIV Stigma is Associated with Two-Year Decline in Cognitive Performance Among People with HIV

HIV stigma is associated with suboptimal clinical outcomes and has been cross-sectionally linked to cognitive deficits in people with HIV (PWH). However, it is unclear whether HIV stigma precedes cognitive decline or vice versa. We examined associations in 303 adult PWH (mean age 50.01 (11.91) years; 46% female; 67% non-Hispanic Black) between the abbreviated Berger Stigma Scale score and longitudinal change across the NIH Toolbox Cognition Battery measures. 89% of participants reported experiencing HIV stigma. In unadjusted analyses, greater HIV stigma was associated with worse attention performance at yearly follow-up visits (B = -0.07, 95% CI = -0.13 - -0.01, p = 0.025). When adjusting for clinicodemographic variables, HIV stigma was associated with worse processing speed and global cognition at yearly follow-up visits. This finding suggests that HIV stigma precedes subsequent cognitive decline and highlights the importance of reducing stigma to improve cognitive functioning among PWH.

Deleterious effects of social isolation on neuroendocrine-immune status, and cancer progression in rats

Accumulating evidence indicates that social isolation (SI) in humans and rodents is associated with increased cancer incidence and mortality, yet mediating mechanisms remain elusive. Here, we examine the neuroendocrine and immunological consequences of SI and its short- and long-term physiological impacts in naïve and cancer-bearing rats. Findings indicate that isolated animals experienced a significant decrease in weight compared to controls. Specifically, females showed a marked weight decrease during the first week of isolation. Isolated rats had significantly higher numbers of MADB106 experimental pulmonary metastases. Although mortality rates were higher in isolated tumor-bearing rats, unexpectedly, they exhibited a reduced growth rate of orthotopically implanted MADB106 tumors. Transcriptomic analyses of these excised tumors indicated a major downregulation in the expression of various genes, including those associated with pro-metastatic processes (e.g., EMT). In naïve rats (no cancer), levels of IL-6 increased, and total IgG levels decreased under SI conditions. A mixed effect was found for TNFα, which increased in females and decreased in males. In the central nervous system, isolated rats showed altered gene expression in key brain regions associated with stress responses and social behavior. The paraventricular nucleus of the thalamus emerged as a significantly affected region, along with the bed nucleus of the stria terminalis. Changes were observed in the expression of oxytocin, serotonin, and dopamine receptors. Isolated rats also exhibited greater alterations in hypothalamic-pituitary-adrenal (HPA) axis-related regulation and an increase in plasma CORT levels. Our study highlights the profound impact of SI on metastatic processes. Additionally, the potential detrimental effects of SI on thermoregulation were discussed, emphasizing the importance of social thermoregulation in maintaining physiological stability and highlighting the need to avoid single-caging practices in research. We report neuro-immune interactions and changes in brain gene expression, highlighting the need for further research into these underlying processes to improve outcomes in animal models and potential interventions for cancer patients through increased social support.

Evaluating the potential effects of apigenin on memory, anxiety, and social interaction amelioration after social isolation stress

Vigorous research confirmed the anti-inflammatory, antioxidant, and antidementia effects of apigenin (Api). The present study evaluated the beneficial impacts of Api administration on behaviour, brain-derived neurotrophic factor (BDNF), Interleukin 6 (IL-6), oxidative stress, and inflammation induced by social isolation (SI) stress in rats. For this purpose, rats underwent a 28-day SI period followed by a 4-week oral Api treatment (50 mg/kg/day, PO). On Day 56, behaviour tests were performed, including an elevated plus maze (EPM), Morris water maze (MWM), and three-chamber social tests. The oxidative stress markers, IL-6, and BDNF levels were measured in the hippocampus. Our results showed that SI stress caused an increase in anxiety and a decrease in spatial memory, sociability, and social preference index. In addition, SI stress increased hippocampal levels of IL-6 and malondialdehyde (MDA) content, whereas it reduced the hippocampal BDNF level and superoxide dismutase (SOD) activities. Our study indicated that Api attenuates anxiety and causes improvements in spatial memory and social interaction. These desirable effects of Api might be related to amelioration in the BDNF level, IL-6, and oxidative stress biomarkers in the hippocampus.

Longitudinal association of social isolation and loneliness with physical function among in-patients living with schizophrenia

WHAT IS KNOWN ON THE SUBJECT?: People living with schizophrenia have reduced physical function and are more likely to experience loneliness than those without condition. Low physical function is associated with greater loneliness in people with psychosis. However, it is unclear whether social isolation and loneliness contribute to impaired physical function in this population. Loneliness is linked to an increased risk of physical function impairment among older individuals, but research on patients living with schizophrenia is limited. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: This study is the first to evaluate the longitudinal association of social isolation and loneliness with physical function among inpatients living with schizophrenia. It showed that more than one third of the participants experienced a decline in physical function over a 2-year period. Loneliness, rather than social isolation, was associated with an increase in physical function impairment over 2 years among inpatients living with schizophrenia. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Healthcare professionals should recognize loneliness as a potential risk factor for impaired physical function among inpatients diagnosed with schizophrenia. It is recommended that people living with schizophrenia are assessed for loneliness and that interventions are offered to alleviate their feelings of loneliness. Implementing interventions to reduce loneliness may help improve physical function and overall quality of life for individuals living with schizophrenia.

ABSTRACT

INTRODUCTION: Patients living with schizophrenia often experience low physical function, which is associated with negative health outcomes. Therefore, investigating the risk factors for physical function is crucial in this population.

AIM

This study examined the longitudinal association of social isolation and loneliness with physical function among inpatients living with schizophrenia.

METHODS

Physical function was assessed using measures of activities daily living (ADL), instrumental activities daily living (IADL) and the combination scores of ADL/IADL. Social isolation was indexed with five types of social connection and loneliness was measured using UCLA Loneliness Scale.

RESULTS

Social isolation was not associated with the measures of physical function over 2 years. Loneliness exhibited an association with IADL and ADL/IADL at follow-up, after adjustment for baseline levels of the outcomes. These associations remained when both social isolation and loneliness were simultaneously entered into the model.

DISCUSSION

Loneliness, rather than social isolation, was associated with increased physical function impairment over 2 years among inpatients living with schizophrenia.

IMPLICATIONS FOR PRACTICE

Healthcare professionals should consider loneliness as a potential risk factor for impaired physical function. It would be beneficial to assess patients for loneliness and implement interventions to reduce feelings of loneliness.

Socioeconomic Disadvantage, Neighborhood Belonging, and Inflammation Among Adolescents

OBJECTIVE

Childhood socioeconomic disadvantage is associated with a host of adverse health outcomes across the lifespan. However, there is increasing interest in identifying factors that may promote resilience to disadvantage's effects on health. One promising candidate in this regard is a sense of neighborhood belonging, which could offset health risks by providing a sense of connection to others, as well as a sense of belonging to a community larger than oneself.

METHODS

In a sample of 245 adolescents (age: mean [standard deviation] = 15.98 [0.54] years; sex: 64.1% female; race: 41.6% White, 37.6% Black/African American, 9.8% Other; ethnicity: 68.6% non-Hispanic), we examined neighborhood belonging as a moderator of the relationship between socioeconomic disadvantage (measured on a 0- to 5-point scale, mean [standard deviation] = 1.21 [1.36]) and low-grade inflammation (measured via a composite of circulating inflammatory biomarkers including IL-6, IL-8, IL-10, TNF-α, CRP, and suPAR). Covariates included age, sex, race/ethnicity, and pubertal status.

RESULTS

Neighborhood belonging buffered the relationship between socioeconomic disadvantage and low-grade inflammation, a key mechanistic pathway to multiple chronic diseases. Specifically, there was a positive relationship between socioeconomic disadvantage and low-grade inflammation among individuals with low neighborhood belonging, but not among individuals with high neighborhood belonging.

CONCLUSIONS

These findings suggest that neighborhood belonging is one type of social connection factor that can mitigate the relationship between socioeconomic disadvantage and low-grade inflammation in youth.

The relationship between social capital and inflammatory biomarkers in early adulthood: A longitudinal study

Higher levels of social capital (SC) are associated with better health status. However, there is little evidence of the impact of SC on biological health outcomes in the early ages. To identify the association between SC in adolescence and inflammation levels in early adulthood. Prospective study using data from 2435 participants from the Epidemiological Health Investigation of Teenagers in Porto cohort. SC was assessed at age 17 through a self-administered questionnaire, and high-sensitivity C-reactive protein (hs-CRP) and leucocytes were measured in a fasting blood sample at 17 and 21 years-old. A principal components analysis was performed to identify the domains of SC. Simple linear regressions were performed to assess the association between SC components and inflammatory status at 17 and 21 years old. Pathway analysis was performed to assess the direct, indirect, and total effects of SC on hs-CRP and leucocyte levels. We did not find a significant total effect between SC at 17 years-old and hs-CRP at 21 years-old. However, the Trust/Reciprocity dimension showed a significant direct effect between SC and hs-CRP levels at 21 (β = -0.065, 95% CI: -0.129; -0.001), as well as a significant total effect (β = -0.075, 95% CI: -0.139; -0.011). Regarding leucocyte levels, total SC at 17 years-old was associated with leucocytes levels at 21 (β = -0.115, 95% CI: -0.205; -0.024). Significant direct (β = -0.104, 95% CI: -0.194; -0.014) and total effect (β = -0.107, 95% CI: -0.199; -0.015) of Trust/Reciprocity on leucocyte levels were observed. Adolescents with higher SC have a low inflammatory level in early adulthood, especially those with greater levels of trust/reciprocity.

Korean Red Ginseng and Rb1 restore altered social interaction, gene expressions in the medial prefrontal cortex, and gut metabolites under post-weaning social isolation in mice

Background

Post-weaning social isolation (SI) reduces sociability, gene expressions including myelin genes in the medial prefrontal cortex (mPFC), and alters microbiome compositions in rodent models. Korean Red Ginseng (KRG) and its major ginsenoside Rb1 have been reported to affect myelin formation and gut metabolites. However, their effects under post-weaning SI have not been investigated. This study investigated the effects of KRG and Rb1 on sociability, gene expressions in the mPFC, and gut metabolites under post-weaning SI.

Methods

C57BL/6J mice were administered with water or KRG (150, 400 mg/kg) or Rb1 (0.1 mg/kg) under SI or regular environment (RE) for 2 weeks during the post-weaning period (P21-P35). After this period, mice underwent a sociability test, and then brains and ceca were collected for qPCR/immunohistochemistry and non-targeted metabolomics, respectively.

Results

SI reduced sociability compared to RE; however, KRG (400 mg/kg) and Rb1 significantly restored sociability under SI. In the mPFC, expressions of genes related to myelin, neurotransmitter, and oxidative stress were significantly reduced in mice under SI compared to RE conditions. Under SI, KRG and Rb1 recovered the altered expressions of several genes in the mPFC. In gut metabolomics, 313 metabolites were identified as significant among 3027 detected metabolites. Among the significantly changed metabolites in SI, some were recovered by KRG or Rb1, including metabolites related to stress axis, inflammation, and DNA damage.

Conclusion

Altered sociability, gene expression levels in the mPFC, and gut metabolites induced by two weeks of post-weaning SI were at least partially recovered by KRG and Rb1.

The role of emotion in urban development decision-making: A qualitative exploration of the perspectives of decision-makers

People's feelings about their neighbourhoods are important for health, but they may be undervalued in urban development decision-making. This study explores how decision-makers understand and respond to residents' emotions. Reflexive thematic analysis was conducted on a secondary dataset consisting of 123 interviews with influential professionals in urban development decision-making. We developed three themes and one subtheme: '(mis)understanding residents' emotions', 'neglecting the health impact of positive emotions', 'avoidance of emotion in community engagement' and 'sanitized emotions'. We recommend decision-makers engage directly with residents' emotions during urban development processes to ensure healthier place-making.

Estimating risk of loneliness in adulthood using survey-based prediction models: A cohort study

It is widely accepted that loneliness is associated with health problems, but less is known about the predictors of loneliness. In this study, we constructed a model to predict individual risk of loneliness during adulthood. Data were from the prospective population-based FinHealth cohort study with 3444 participants (mean age 55.5 years, 53.4% women) who responded to a 81-item self-administered questionnaire and reported not to be lonely at baseline in 2017. The outcome was self-reported loneliness at follow-up in 2020. Predictive models were constructed using bootstrap enhanced LASSO regression (bolasso). The C-index from the final model including 11 predictors from the best bolasso -models varied between 0.65 (95% CI 0.61 to 0.70) and 0.71 (95% CI 0.67 to 0.75) the pooled C -index being 0.68 (95% CI 0.61 to 0.75). Although survey-based individualised prediction models for loneliness achieved a reasonable C-index, their predictive value was limited. High detection rates were associated with high false positive rates, while lower false positive rates were associated with low detection rates. These findings suggest that incident loneliness during adulthood. may be difficult to predict with standard survey data.

Cross-sectional association of food insecurity with loneliness in older adults: The role of sex, age, and psychosomatic factors

OBJECTIVE

Food insecurity (FI) is a critical social determinant of poor psychosocial health. While data on the specific roles of sex and age in the FI-loneliness link among older adults are limited, the underlying mechanisms are largely unknown. This study examines the age-sex-specific associations of FI with loneliness among older adults in Ghana and quantifies the extent to which psychosomatic factors mediate the association.

METHODS

We analyzed cross-sectional data from the Aging, Health, Psychological, and Health-seeking Behavior Study in Ghana. The past 30-day FI was assessed using items on hunger and breakfast skipping frequency due to a lack of resources. We assessed loneliness severity with the University of California, Los Angeles 3-item Loneliness Scale. Multivariable OLS regressions and bootstrapping mediation analysis using the Hayes PROCESS macro plug-in were used to evaluate the associations.

RESULTS

We included 1,201 individuals aged ≥50 years (mean = 62.9 [SD = 11.9]; women = 63.3%). The prevalence of loneliness was 17.7%. The prevalence of moderate and severe FI was 44.0% and 8.5%, respectively. In the adjusted model, greater FI was significantly associated with loneliness severity (B = .22, SE = .029, p < .001). We found significant interactive effects of FI × age (B = -.17, SE = .023, p < .01) and FI × sex (B = -.28, SE = .036, p < .001) on loneliness. Thus, the FI-loneliness link was respectively more marked among women (B = .25, SE = .035, p < .001) and ≥65 age groups (B = .34, SE = .041, p < .001) than men (B = .16, SE = .051, p < .01) and those aged 50-64 (B = .22; SE = .040, p < .001). Finally, comorbid depression/anxiety (41.07%), hopelessness (48.6%), worthlessness (42.1%), functional limitations (8.2%), and pain severity (6.4%) mediated the FI-loneliness association.

CONCLUSIONS

Age- and sex-specific associations between FI and loneliness exist among older Ghanaians. Addressing FI in concert with psychosomatic problems in older adults may contribute meaningfully to reducing loneliness in later life.

Interpersonal relationships, PNI, and health: Seeds in the 1980s, fruiting trees today

In this contribution to the Special Issue, I highlight how Janice Kiecolt-Glaser's research in the 1980s planted the seeds for two areas of social relationships and health research: loneliness and intimate/marital relationships. I review the foundational "seed" studies from the mid-to late-1980s, the research "saplings" that sprouted and grew during the subsequent twenty years, and the "mature trees" that have gone on to fruit and grow their respective areas of inquiry over the past twenty years. In addition to highlighting the mature trees that have borne rich empirical fruit, my other goal for this contribution is to draw attention to ideas and concepts from Kiecolt-Glaser's work and writing that merit further conceptual and empirical examination in the next generation of research on social relationships, psychoneuroendocrinology, psychoneuroimmunology, and health.

Loneliness Among Black/African American Adults Living with HIV: Sociodemographic and Psychosocial Correlates and Implications for Adherence

Loneliness, an emerging public health problem, is higher among people living with HIV and is associated with negative health outcomes. Black/African Americans have a high burden of HIV, and little is known about the characteristics of loneliness among Black adults living with HIV; therefore, this study sought to understand the sociodemographic and psychosocial correlates of Black adults living with HIV who are lonely and the implications of loneliness for their health outcomes. A sample of 304 Black adults living with HIV (73.8% sexual minority men) in Los Angeles County, CA, USA, completed the survey items assessing sociodemographic and psychosocial characteristics, social determinants of health, health outcomes, and loneliness. Antiretroviral therapy (ART) adherence was assessed electronically with the medication event monitoring system. Bivariate linear regressions analysis showed higher loneliness scores among those with higher levels of internalized HIV stigma, depression, unmet needs, and discrimination related to HIV serostatus, race, and sexual orientation. In addition, participants who were married or living with a partner, had stable housing, and reported receiving more social support had lower levels of loneliness. In multivariable regression models controlling for correlates of loneliness, loneliness was found to be a significant independent predictor of worse general physical health, worse general mental health, and greater depression. Loneliness was marginally associated with lower ART adherence. Findings suggest that Black adults living with HIV, who experience multiple intersectional stigmas, require targeted interventions and resources.

Moving toward affective immunology: Legacy and future directions

The term "affective immunology" has recently been used to denote a field focused on the interplay between affective processes (including mood states, specific emotions, and regulatory processes) and various aspects of immune function. The overarching goals of this commentary are a) to provide historical underpinnings of this field with a focus on the profound impact of the work of Janice Kiecolt-Glaser, who is further honored in this special issue, b) to review important off-shoots of her legacy work in this domain, and c) to highlight important future directions for the field. Kiecolt-Glaser's work laid much of the foundation for affective immunology, with groundbreaking research related to depression, hostility and dyadic interactions, loneliness, and other affective patterns, often in the context of holistic models, novel experimental designs, and interventions. Her former mentees (and many of their mentees) have carried on her legacy in these domains, in ways that continue to advance appreciation of how affective processes relate to immune function. There are numerous remaining questions for the field to pursue, including better understanding of the role of emotion regulation, emotional reactivity and recovery, restorative processes, affective variability, and developmental and dynamic social processes. Such work will require greater use of longitudinal and within-person approaches and/or examination of processes in daily life, as well as models that account for interactive and reciprocal processes and which integrate behavior, social context, sociocultural factors, individual differences, and other aspects of health. As more work in these domains continues, building on Kiecolt-Glaser's rich legacy, we move toward the emergence of affective immunology as an important subfield in the domain of psychoneuroimmunology, one which will offer more nuanced understanding of the role of affective processes in immune health.

A translational neuroscience perspective on loneliness: Narrative review focusing on social interaction, illness and oxytocin

This review addresses key findings on loneliness from the social, neurobiological and clinical fields. From a translational perspective, results from studies in humans and animals are included, with a focus on social interaction, mental and physical illness and the role of oxytocin in loneliness. In terms of social interactions, lonely individuals tend to exhibit a range of abnormal behaviors based on dysfunctional social cognitions that make it difficult for them to form meaningful relationships. Neurobiologically, a link has been established between loneliness and the hypothalamic peptide hormone oxytocin. Since social interactions and especially social touch regulate oxytocin signaling, lonely individuals may have an oxytocin imbalance, which in turn affects their health and well-being. Clinically, loneliness is a predictor of physical and mental illness and leads to increased morbidity and mortality. There is evidence that psychopathology is both a cause and a consequence of loneliness. The final section of this review summarizes the findings from social, neurobiological and clinical perspectives to present a new model of the complex construct of loneliness.

Loneliness as a moderator of the association of affective symptoms and binge eating among college women

Affective symptoms (e.g., depression, anxiety, shame) are a potent risk factor for binge eating. However, less is known on the role of loneliness as a moderator of affective symptoms and binge eating. This objective of the current study was to investigate main effects and interactions of affective symptoms and loneliness in relation to binge eating in college women. A sample of 556 undergraduate women completed self-report questionnaires of affective symptoms, loneliness, and binge eating. Results revealed significant interactions between each affective symptom variable and loneliness in relation to binge eating, such that loneliness strengthened the positive association of affective symptoms and greater binge eating. The findings of this study demonstrate an important role of loneliness to binge eating among college women, especially those with underlying affective vulnerabilities. More theoretical and treatment-oriented work on the role of loneliness in binge eating is needed to understand mechanisms and interventions/preventions.

The reciprocal associations between social deficits, social engagement, and inflammation: Longitudinal evidence comparing venous blood samples and dried blood spots and mapping the modifying role of phenotypic and genotypic depression

BACKGROUND

Social psychoneuroimmunology suggests an interplay between social deficits (loneliness and isolation) and chronic inflammation, but the direction of these relationships remains unclear. We estimated the reciprocal associations of social deficits and social engagement with levels of C-reactive protein (CRP), compared the consistency of the findings depending on the biological sampling method used, and examined the modifying role of phenotypic and genotypic depression.

METHODS

We used longitudinal nationally representative data from the US (Health and Retirement Study, 3 waves, 2006-16) and England (English Longitudinal Study of Ageing, 4 waves, 2004-18). Loneliness, social isolation, and social engagement were self-reported. CRP was measured using dried blood spots (US) and venous blood samples (England). Cross-lagged panel models were fitted and tested interactions with phenotypic depression (above-threshold depressive symptom scores) and genotypic depression (polygenic score for major depressive disorder).

RESULTS

We included 15,066 participants (mean age = 66.1 years, SD = 9.8) in the US and 10,290 (66.9 years, SD = 10.5) in England. We found reciprocal associations between loneliness and CRP using dried blood spots and venous blood samples. Higher CRP predicted higher subsequent loneliness and higher loneliness predicted elevated CRP. Both phenotypic and genotypic depression modified this reciprocal association. There were also reciprocal associations for social engagement in venous blood samples: higher CRP predicted lower social engagement and greater social engagement predicted lower subsequent CRP. Associations between social isolation and CRP were inconsistent and unidirectional.

CONCLUSIONS

Loneliness may increase chronic inflammation, whereas social engagement may reduce inflammation. As these relationships were reciprocal, there may be a loop between inflammation, loneliness, and social engagement. This loop was stronger in those with depression or at high genetic risk for major depressive disorder. This relationship for loneliness was present in both blood sampling methods despite contrasting methods of CRP measurement, indicating that the finding is not attributable to measurement bias in biomarkers.

Longitudinal associations of loneliness and social isolation with care dependence among older adults in Latin America and China: A 10/66 dementia research group population-based cohort study

OBJECTIVES

With increasing life expectancy and rapid ageing, there is an expanding number of older people who have functional declines, greater needs for care and support and who are at increased risk of insufficient social interaction. Longitudinal investigations on the interplay between loneliness, social isolation and care dependence remain limited. This study thus aimed to investigate the longitudinal reciprocal association between social isolation/loneliness and care dependence among older adults in Latin America and China.

METHODS

We analysed data from the population-based cohorts from the 10/66 Dementia Research Group (DRG) project (baseline 2003-07 and follow-up 2007-2010). The 10/66 DRG study recruited and followed up older adults aged 65 years or above in 11 catchment areas in Latin America and China. A total of 15,027 older adults from Latin America and China (mean age = 73.5, standard deviation = 6.5) were included in our analyses. Cross-lagged panel models were used to investigate potential reciprocal associations.

RESULTS

Loneliness was positively associated with care dependence at baseline (β = 0.11, p < 0.001 in Latin America; β = 0.16, p < 0.05 in China]. Social isolation consistently had a stronger positive association with care dependence across all study sites in both waves. Longitudinally, care dependence positively predicted loneliness (β = 0.10, p < 0.001) and social isolation (β = 0.05, p < 0.001) in Latin American study sites but not in China. Yet there was no statistical evidence of lagged effects of loneliness and social isolation on care dependence in all study countries.

CONCLUSIONS

Older people with care dependence are at risk of developing loneliness and social isolation. It is crucial to develop complex care models using a societal approach to address social and care needs holistically, especially for the older group with declining functional capacity. Future longitudinal research is required to explore the causal mechanisms of relationships and cultural differences, in order to inform the development of culturally appropriate care models.

The loneliness factor in eating disorders: Implications for psychopathology and biological signatures

OBJECTIVES

Eating disorders (ED) are severe psychiatric conditions. While the biological consequences of EDs are well established, including an increase in inflammatory biomarkers, the influence of psychological factors, such as loneliness, has only recently gained attention in research. Loneliness has been associated with more severe psychopathology in ED patients, while its association with inflammatory biomarkers has only been explored in the general population. For these reasons, we aimed to investigate any possible associations between psychological features, trauma, and inflammatory biomarkers with loneliness in people with ED.

METHODS

This study examined the interaction between loneliness, eating psychopathology, and biological markers in people with EDs. A group of 97 female patients with various diagnoses of ED was assessed for loneliness, general and eating psychopathology, traumatic history during childhood, and clinical biomarkers such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and urinary-free cortisol (UFC).

RESULTS

The results indicated that individuals with ED who reported moderate to severe loneliness also displayed greater general psychopathology (p = 0.001), weight concerns (p = 0.007), and physical neglect during childhood (p = 0.006). Furthermore, people with higher levels of loneliness also had higher inflammatory indexes (ESR p = 0.001, CRP p = 0.027) and were positively correlated with markers of stress reaction such as UFC (p < 0.05).

CONCLUSION

The findings underscore the importance of considering loneliness in the assessment of individuals with an ED. We observed notable associations between loneliness and increased psychopathology (both general and specific to eating), as well as higher levels of inflammation and childhood physical neglect. Addressing loneliness may contribute to improving overall well-being and potentially support recovery. This consideration encompasses both psychological and physical factors that interplay in the clinical presentation of individuals.

Childhood Racism and Cardiometabolic Risk in Latina Mothers Across the First Postpartum Year

OBJECTIVE

Immigrant Latinas, particularly of Mexican descent, initially achieve healthy perinatal outcomes. Although this advantage wears off across generations in the United States (US), the early life psychosocial mechanisms that may initiate a cascade of biological vulnerabilities remain elusive. The current investigation aimed to understand the extent to which childhood experiences of racism may contribute to elevated levels of C-reactive protein (CRP), an early indicator of cardiometabolic risk, during the first postpartum year.

METHODS

Latinas from the Community and Child Health Network ( N = 457) retrospectively reported experiences of childhood racism and childhood country of residence via structured questionnaires. Interviewers collected CRP bloodspots and height and weight measurements for body mass index at 6 months and 1 year postpartum.

RESULTS

Latinas who grew up in the US experienced a steeper increase of CRP levels across the first postpartum year ( β = 0.131, p = .009) and had higher CRP levels 1 year postpartum than Latinas who grew up in Latin America. Based on Bayesian path analyses, Latinas who grew up in the US reported higher levels of childhood racism than Latinas who immigrated after childhood ( β = 0.27; 95% credible interval = 0.16-0.37). In turn, childhood racism mediated the relationship between country of childhood residence and elevated CRP at 6 months and 1 year postpartum, even after adjusting for sociodemographic and behavioral covariates. After adjusting for body mass index, mediational relationships became nonsignificant.

CONCLUSIONS

This study is an important first step toward understanding how childhood racism may contribute to postmigratory health patterns among Latinas, particularly cardiometabolic risk 1 year after childbirth.

Systemic inflammation, lifestyle behaviours and dementia: A 10-year follow-up investigation

Objectives

Lifestyle behaviours have been linked to dementia incidence, but their cumulative impact on dementia and the underlying mechanisms remain poorly understood. This study investigated the association of co-occurring lifestyle behaviours with dementia incidence and the mediating role of systemic inflammation in this association.

Methods

The sample comprised 3131 participants (55.2% female) from the English Longitudinal Study of Ageing aged 52-92 years at baseline (2008/09). Self-reported baseline lifestyle behaviours (alcohol intake, fruit and vegetable consumption, smoking, physical activity, sleep duration, social engagement, and cognitive activity) were summed to derive an index of lifestyle behaviours, ranging from 0 to 7, with higher scores denoting a higher number of health-risk behaviours. Incident dementia cases (n = 130, 4.2%) were identified through doctor-diagnosed dementia, informant interviews, and health records between 2014/15 and 2018/19. Systemic inflammation was measured through fasting plasma concentrations of C-reactive protein in 2012/13.

Results

Binary logistic regression models indicated that the odds of subsequent dementia increased by 1.19 for each additional health-risk behaviour (95% confidence intervals: 1.04, 1.37, p = 0.014) after adjusting for age, sex, ethnicity, wealth, education, marital status, body mass index, coronary heart disease, hypertension, stroke, and depression. However, this association was not mediated by C-reactive protein.

Conclusions

Co-occurring health-risk behaviours were associated with higher dementia incidence up to 10 years later, underscoring the importance of modifying health-risk behaviours for the prevention of dementia. Systemic inflammation did not explain the association between behaviours and dementia.

Psychosocial and behavioural predictors of immune response to influenza vaccination: a systematic review and meta-analysis

High variability of influenza vaccine efficacy requires the identification of modulators of immunisation that may be targeted as adjuvants in health psychology interventions. Psychosocial and behavioural variables such as psychological stress, greater negative and lower positive affectivity, poor sleep, loneliness, and lack of social support, have been associated with abnormal immune and inflammatory responses and negative health outcomes, yet their effects in modulating vaccine efficacy are yet to be fully understood. We conducted an updated systematic review of longitudinal and experimental studies examining the effects of such variables in predicting immune response to influenza vaccine. PubMed, Medline, PsycINFO, CINAHL and Scopus were searched up to November 2022. Twenty-five studies met the inclusion criteria for qualitative synthesis and 16 provided data for meta-analysis. Low positive and high negative affect were associated with low antibodies and weak cell-mediated immunity following vaccination in qualitative synthesis. Literature on sleep disturbance, loneliness and social support was limited and yielded inconsistent results. Psychological stress was associated with poorer antibody response in meta-analysis. In conclusion, findings from this review suggest a need for further longitudinal and experimental studies on these factors to support their inclusion as target variables in vaccine adjuvant interventions.

Examining mental health and autonomic function as putative mediators of the relationship between sleep and trajectories of cognitive function: findings from the Irish longitudinal study on ageing (TILDA)

OBJECTIVES

This study investigates the mediating roles of autonomic function and mental health in the association between sleep and cognitive decline in adults aged 50 and above.

METHOD

A total of 2,697 participants with observations on sleep and mediators at baseline and repeated measures of cognitive function (MMSE) were included. Clusters of individuals with similar cognitive trajectories (high-stable, mid-stable and low-declining) were identified. Multinomial logistic regressions were used to estimate the likelihood of membership to each trajectory group based on sleep duration and disturbance. Finally, mediation analysis tested potential mediating effects of autonomic function and mental health underpinning the sleep-cognition relationship.

RESULTS

Short (p = .028), long (p =.019), and disturbed sleep (p =.008) increased the likelihood of a low-declining cognitive trajectory. Mental health measures fully attenuated relationships between cognitive decline and short or disturbed sleep but not long sleep. No autonomic function mediation was observed.

CONCLUSION

Older adults with short or disturbed sleep are at risk of cognitive decline due to poor mental health. Individuals with long sleep are also at risk, however, the acting pathways remain to be identified. These outcomes have clinical implications, potentially identifying intervention strategies targeting mental health and sleep as prophylactic measures against dementia.

Trajectories of social isolation and loneliness and the risk of incident type 2 diabetes mellitus across genetic risk score

AIM

This study aimed to investigate the association of social isolation, loneliness, and their trajectory with the risk of developing type 2 diabetes mellitus (T2DM) across genetic risk.

METHODS

We included 439,337 participants (mean age 56.3 ± 8.1 years) enrolled in the UK Biobank study who were followed up until May 31, 2021. Social isolation and loneliness were self-reported and were further categorized into never, transient, incident, and persistent patterns.

RESULTS

During a median follow-up of 12.7 years, 15,258 incident T2DM cases were documented. Social isolation (versus no social isolation: hazard ratio (HR) 95 % confidence interval (CI) 1.04 [1.00;1.09]) and loneliness (versus no loneliness: 1.26 [1.19;1.34]) were associated with an increased T2DM risk, independent of the genetic risk for T2DM. The interactions existed between social isolation and loneliness (Pinteraction < 0.05); the increased T2DM risk associated with social isolation was only significant among participants without loneliness. In the longitudinal analysis, only persistent social isolation (versus never social isolation: 1.22 [1.02;1.45]) was associated with an increased T2DM risk, whereas incident loneliness (versus never loneliness: 1.95 [1.40;2.71]) and persistent loneliness (2.00 [1.31;3.04]) were associated with higher T2DM risks.

CONCLUSION

Social isolation and loneliness, especially their persistent pattern, were independently associated with an increased incident T2DM risk, irrespective of an individual's genetic risk. Loneliness modified the association between social isolation and incident T2DM.

The beneficial effects of social support and prosocial behavior on immunity and health: A psychoneuroimmunology perspective

The COVID-19 pandemic emphasized the pivotal role of the social environment, prompting a surge in research on its impact on well-being and health. This article aims to examine the link between the social environment, the immune system, and health outcomes, with a particular focus on positive aspects like social support and prosocial behaviors that are under-explored. Different aspects of the social environment are examined: the negative effects of loneliness and adverse social conditions, contrasted with the benefits of social support and prosocial behaviors. While the mechanisms behind negative effects are partially studied, those driving the positive effects remain elusive. Understanding the mechanisms of lack of social connection and their effects will allow us to explore the benefits of social connections and whether they can reverse the adverse outcomes. Potential psychoneuroimmunology mechanisms are proposed, highlighting the promotion of a 'safe' state by the vagus nerve, oxytocin circuits, and the additional contribution of the reward pathways. This article reviews the need to bridge knowledge gaps, urging further research to study the causal effects of positive social interactions on immune response and health outcomes to raise clinical awareness and interventions. Such interventions may include integrating lonely individuals with prosocial activities, thereby improving their physical and mental health. There is growing potential to harness the power of social connections for the betterment of individual health and society as a whole.

Social health and subsequent cognitive functioning in people aged 50 years and older: examining the mediating roles of depressive symptoms and inflammatory biomarkers in two European longitudinal studies

BACKGROUND

Social health markers, including marital status, contact frequency, network size, and social support, have been shown to be associated with cognition. However, the mechanisms underlying these associations remain poorly understood. We investigated whether depressive symptoms and inflammation mediated associations between social health and subsequent cognition.

METHODS

In the English Longitudinal Study of Ageing (ELSA), a nationally representative longitudinal study in England, UK, we sampled 7136 individuals aged 50 years or older living in private households without dementia at baseline or at the intermediate mediator assessment timepoint, who had recorded information on at least one social health marker and potential mediator. We used four-way decomposition to examine to what extent depressive symptoms, C-reactive protein, and fibrinogen mediated associations between social health and subsequent standardised cognition (verbal fluency and delayed and immediate recall), including cognitive change, with slopes derived from multilevel models (12-year slope). We examined whether findings were replicated in the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), a population-based longitudinal study in Sweden, in a sample of 2604 individuals aged 60 years or older living at home or in institutions in Kungsholmen (central Stockholm) without dementia at baseline or at the intermediate mediator assessment timepoint (6-year slope). Social health exposures were assessed at baseline, potential mediators were assessed at an intermediate timepoint (wave 2 in ELSA and 6-year follow-up in SNAC-K); cognitive outcomes were assessed at a single timepoint (wave 3 in ELSA and 12-year follow-up in SNAC-K), and cognitive change (between waves 3 and 9 in ELSA and between 6-year and 12-year follow-ups in SNAC-K).

FINDINGS

The study sample included 7136 participants from ELSA, of whom 3962 (55·5%) were women and 6934 (97·2%) were White; the mean baseline age was 63·8 years (SD 9·4). Replication analyses included 2604 participants from SNAC-K, of whom 1604 (61·6%) were women (SNAC-K did not collect ethnicity data); the mean baseline age was 72·3 years (SD 10·1). In ELSA, we found indirect effects via depressive symptoms of network size, positive support, and less negative support on subsequent verbal fluency, and of positive support on subsequent immediate recall (pure indirect effect [PIE] 0·002 [95% CI 0·001-0·003]). Depressive symptoms also partially mediated associations between less negative support and slower decline in immediate recall (PIE 0·001 [0·000-0·002]) and in delayed recall (PIE 0·001 [0·000-0·002]), and between positive support and slower decline in immediate recall (PIE 0·001 [0·000-0·001]). We did not observe mediation by inflammatory biomarkers. Findings of mediation by depressive symptoms in the association between positive support and verbal fluency and between positive support and change in immediate recall were replicated in SNAC-K.

INTERPRETATION

The findings of this study provide new insights into mechanisms linking social health with cognition, suggesting that associations between interactional aspects of social health, especially social support, and cognition are partly underpinned by depressive symptoms.

FUNDING

EU Joint Programme-Neurodegenerative Disease Research (JPND) and Alzheimer's Society.

TRANSLATION

For the Swedish translation of the abstract see Supplementary Materials section.

Chronically socially isolated mice exhibit depressive-like behavior regulated by the gut microbiota

Objectives

Chronic loneliness is a widespread issue, and the gut-brain axis is known to be crucial in facilitating communication between the gut and brain. However, the precise mechanism by which chronic loneliness affects the gut-brain axis remains uncertain.

Methods

Fourteen 55-week-old Balb/c mice were used in the experiment, with seven mice being randomly assigned to the chronic social isolation (CSI) group. The CSI group mice underwent 12 weeks of isolation to simulate the psychiatric state of a population in prolonged social isolation. The mental state of the CSI mice was assessed through animal behavior analysis, while plasma cytokines were measured using ELISA. Additionally, the composition of the gut microbiota was analyzed using 16S rRNA sequencing, and the metabolite composition of the intestinal contents was examined using nontargeted metabolomics. The Student-T test was used to determine significant mean differences.

Results

Mice that were exposed to the CSI exhibited increased immobility time lengths in forced swimming and hanging tail experiments, and decreased movement lengths and number of times traversing the intermediate region, compared to control mice. Additionally, CSI decreased the abundance of the probiotics Ruminococcaceae, Akkermansiaceae, and Christensenellaceae. Additionally, CSI reduced the production of the metabolites oleamide and tryptophan. Furthermore, IL-1β, IL-4, and IL-6 were significantly increased, while TNF-α was significantly decreased.

Conclusion

CSI induces a dysbiotic gut microbiota and the production of neurorelated metabolites, which in turn increase inflammatory responses and result in depressive behaviors in CSI mice. Therefore, these findings suggest that the gut microbiota may serve as a target for the treatment of long-term social isolation-induced mental disorders.

Social frailty and the incidence of motoric cognitive risk syndrome in older adults

INTRODUCTION

Various associations between social factors and motoric cognitive risk syndrome (MCR) have been reported. However, whether social frailty (integrated from multiple social factors) is associated with MCR is still unclear.

METHODS

We included 4657 individuals without MCR at Round 1 of the NHATS as the discovery sample, and 3075 newly recruited individuals from Round 5 of the NHATS as the independent validation sample. Social frailty was assessed by five social items. MCR was defined as the presence of both subjective cognitive complaints and slow gait speed in individuals without dementia or mobility disability.

RESULTS

Compared with normal individuals, those with social frailty had higher risk of incident MCR (hazard ratio [HR]: 1.57, 95% confidence interval [CI]: 1.34-1.84). Each additional unfavorable social item was associated with an increased risk of MCR (HR: 1.32, 95% CI: 1.22-1.43).

DISCUSSION

Social frailty was associated with an increased risk of incident MCR in older adults.

HIGHLIGHTS

Various associations between social factors and motoric cognitive risk syndrome (MCR) have been reported. Social frailty that integrated from multiple social factors was associated with an increased risk of incident MCR. Social frailty should be included in the early screening of individuals to identify those at higher risk of MCR.

Loneliness and the risk of type 2 diabetes

INTRODUCTION

The incidence of type 2 diabetes is increasing globally. Recent research suggests that loneliness could be a potential risk factor for the development of type 2 diabetes. We aimed to investigate the association between loneliness and type 2 diabetes and the modifying effect of mental disorders.

RESEARCH DESIGN AND METHODS

We conducted a prospective study including 465 290 adults (aged ≥16 years) who participated in either the Danish Health and Morbidity Survey or the Danish National Health Survey between 2000 and 2017. Loneliness was based on self-report, while type 2 diabetes was measured using an algorithm combining several health registers including type 2 diabetes patients treated both within the hospital sector and general practice. Cox proportional hazards regressions were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs).

RESULTS

During a mean follow-up time of 6.3 years, 13 771 individuals (3%) developed type 2 diabetes. Feeling lonely once in a while was associated with a 14% increased risk of type 2 diabetes (95% CI 1.09 to 1.20), while feeling lonely often was associated with a 24% increased risk (95% CI 1.14 to 1.34), independent of sociodemographic factors and body mass index. The association was stronger among individuals without a mental disorder (HR 1.21, 95% CI 1.10 to 1.34 among those feeling lonely often) compared with those with a mental disorder (HR 1.07, 95% CI 0.93 to 1.23).

CONCLUSIONS

Loneliness independently increased the risk of type 2 diabetes. The effect was more pronounced in individuals without a mental disorder, as having a mental disorder itself likely increases the risk of type 2 diabetes. These findings emphasize the importance of addressing loneliness as a modifiable risk factor in preventing type 2 diabetes.

Umbrella review and Delphi study on modifiable factors for dementia risk reduction

A 2013 systematic review and Delphi consensus study identified 12 modifiable risk and protective factors for dementia, which were subsequently merged into the "LIfestyle for BRAin health" (LIBRA) score. We systematically evaluated whether LIBRA requires revision based on new evidence. To identify modifiable risk and protective factors suitable for dementia risk reduction, we combined an umbrella review of systematic reviews and meta-analyses with a two-round Delphi consensus study. The review of 608 unique primary studies and opinions of 18 experts prioritized six modifiable factors: hearing impairment, social contact, sleep, life course inequalities, atrial fibrillation, and psychological stress. Based on expert ranking, hearing impairment, social contact, and sleep were considered the most suitable candidates for inclusion in updated dementia risk scores. As such, the current study shows that dementia risk scores need systematic updates based on emerging evidence. Future studies will validate the updated LIBRA score in different cohorts. HIGHLIGHTS: An umbrella review was combined with opinions of 18 dementia experts. Various candidate targets for dementia risk reduction were identified. Experts prioritized hearing impairment, social contact, and sleep. Re-assessment of dementia risk scores is encouraged. Future work should evaluate the predictive validity of updated risk scores.

The role of frailty in the relationships between social relationships and health outcomes: a longitudinal study

BACKGROUND

Socially isolated older adults incur increased risks of adverse health outcomes, though the strength of this association is unclear. We examined whether changes in physical frailty moderated the associations between changes in social relationships and changes in health outcomes among older adults.

METHODS

This longitudinal study is based on three waves of the FRéLE study among 1643 Canadian community-dwelling older adults aged 65 years and older over 2 years. We performed latent growth curve modelling (LGMs) to assess changes with the assumption of missing not at random, adjusting for time-invariant covariates. We used the latent moderated structural equations (LMS) to test the interactions in LGMs. Social relationships were measured by social participation, social networks, and social support from different social ties. Frailty was assessed using the five components of the phenotype of frailty.

RESULTS

The results revealed that changes in frailty moderated changes in social participation (β = 3.229, 95% CI: 2.212, 4.245), social contact with friends (β = 4.980, 95% CI: 3.285, 6.675), and social support from friends (β = 2.406, 95% CI: 1.894, 2.917), children (β = 2.957, 95% CI: 1.932, 3.982), partner (β = 4.170, 95% CI: 3.036, 5.305) and extended family (β = 6.619, 95% CI: 2.309, 10.923) with changes in cognitive function and depressive symptoms, but not with chronic diseases. These results highlight the beneficial role of social relationships in declining depressive symptoms and improving cognitive health among older adults experiencing increases in frailty.

CONCLUSIONS

The findings suggest that changes in social support have a protective and compensatory role in decreasing depressive symptoms and enhancing cognitive health among older adults with increasing frailty. Public health policy and strategies should consider the impact of social support on multiple health outcomes among older adults with increasing frailty. Further experimental studies and interventions are warranted to extend findings on the relationships between social relationships and health outcomes, targeting frail older adults. Future studies may also consider other health-related risk factors that may impact the associations between social relationships and health outcomes among older adults.

Risk of Social Isolation as a Contributing Factor to Diet Quality in Community-Dwelling Older Persons Living in the Australian Capital Territory-A Pilot Study

OBJECTIVES

Social isolation is recognised as a risk factor in the inflammatory process. This study explored the association between social isolation and the Dietary Inflammatory Index (DII) in community-dwelling older persons.

METHODS

This cross-sectional pilot study recruited 107 community-dwelling people aged over 55 years living in the Australian Capital Territory. Participants completed an extensive food frequency questionnaire and provided anthropometric and sociodemographic data. Social isolation was evaluated using the Lubben Social Network Scale (LSNS). Diet quality was assessed using DII.

RESULTS

Average age was 70.1 (±8.61) years and 62.8% were female. The average DII score was -1.10 (±1.21), indicating an anti-inflammatory diet. Higher LSNS was associated with lower DII (b (95% CI) = -0.041 (-0.066, -0.17); p < 0.01) and was positively influenced by the number of people in household (b (95% CI) = 5.731 (2.336, 9.127); p = 0.001).

CONCLUSION

Increased risk of social isolation was associated with an increased tendency towards a more inflammatory diet. Reducing social isolation may decrease the inflammatory component of dietary intake for older persons living independently in the community.

Impact of the COVID-19 Pandemic on the Personal Networks and Neurological Outcomes of People With Multiple Sclerosis: Cross-Sectional and Longitudinal Case-Control Study

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has negatively affected the social fabric.

OBJECTIVE

We evaluated the associations between personal social networks and neurological function in people with multiple sclerosis (pwMS) and controls in the prepandemic and pandemic periods.

METHODS

During the early pandemic (March-December 2020), 8 cohorts of pwMS and controls completed a questionnaire quantifying the structure and composition of their personal social networks, including the health behaviors of network members. Participants from 3 of the 8 cohorts had additionally completed the questionnaire before the pandemic (2017-2019). We assessed neurological function using 3 interrelated patient-reported outcomes: Patient Determined Disease Steps (PDDS), Multiple Sclerosis Rating Scale-Revised (MSRS-R), and Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function. We identified the network features associated with neurological function using paired 2-tailed t tests and covariate-adjusted regressions.

RESULTS

In the cross-sectional analysis of the pandemic data from 1130 pwMS and 1250 controls during the pandemic, having a higher percentage of network members with a perceived negative health influence was associated with worse disability in pwMS (MSRS-R: β=2.181, 95% CI 1.082-3.279; P<.001) and poor physical function in controls (PROMIS Physical Function: β=-5.707, 95% CI -7.405 to -4.010; P<.001). In the longitudinal analysis of 230 pwMS and 136 controls, the networks of all participants contracted, given an increase in constraint (pwMS-prepandemic: mean 52.24, SD 15.81; pwMS-pandemic: mean 56.77, SD 18.91; P=.006. Controls-prepandemic: mean 48.07, SD 13.36; controls-pandemic: mean 53.99, SD 16.31; P=.001) and a decrease in network size (pwMS-prepandemic: mean 8.02, SD 5.70; pwMS-pandemic: mean 6.63, SD 4.16; P=.003. Controls-prepandemic: mean 8.18, SD 4.05; controls-pandemic: mean 6.44, SD 3.92; P<.001), effective size (pwMS-prepandemic: mean 3.30, SD 1.59; pwMS-pandemic: mean 2.90, SD 1.50; P=.007. Controls-prepandemic: mean 3.85, SD 1.56; controls-pandemic: mean 3.40, SD 1.55; P=.01), and maximum degree (pwMS-prepandemic: mean 4.78, SD 1.86; pwMS-pandemic: mean 4.32, SD 1.92; P=.01. Controls-prepandemic: mean 5.38, SD 1.94; controls-pandemic: mean 4.55, SD 2.06; P<.001). These network changes were not associated with worsening function. The percentage of kin in the networks of pwMS increased (mean 46.06%, SD 29.34% to mean 54.36%, SD 30.16%; P=.003) during the pandemic, a change that was not seen in controls.

CONCLUSIONS

Our findings suggest that high perceived negative health influence in the network was associated with worse function in all participants during the pandemic. The networks of all participants became tighter knit, and the percentage of kin in the networks of pwMS increased during the pandemic. Despite these perturbations in social connections, network changes from the prepandemic to the pandemic period were not associated with worsening function in all participants, suggesting possible resilience.

The effect of EEG neurofeedback on lowering the stress reaction level depending on various stressors on the biochemical, muscular and psychomotor sphere: A preliminary randomized study

BACKGROUND

The human body is exposed to stressors on a daily basis. Short-term exposure to a particular stressor can cause the release of inflammatory markers - including c-reactive protein (CRP). EEG neurofeedback is a noninvasive form of therapy that aims to improve brain function. Neurofeedback is a type of feedback based on brain activity.

METHODS

The research process was performed by a group of 80 men who were divided into 2 research groups and 2 control groups. In the first research group and the first control group, the stressor of high temperature was applied, while in the second research group and the second control group, the stressor was physical exertion to refusal. Meanwhile, blood samples were taken to visualize inflammatory markers. These were taken before and after the stressor, as well as before and after the application of EEG neurofeedback.

RESULTS

In research group after EEG neurofeedback intervention, the level of CRP significantly dropped in the measurement after stressor implementation. Analysis of the SMK test revealed a significant influence of both factors (time F = 13.525, P = .035; state F = 10.658, P = .047) and their interaction (F = 16.709, P = .026). Same statically significant decrease was observed in the level of rect. abdom. EMG was after physical work after neurofeedback. In all tests, a decrease in the EMG amplitude of upper trap. was observed after physical work before neurofeedback with its further increase after neurofeedback. After neurofeedback training, the results of the 3 tested parameters of the sensorimotor coordination test performed after the second heat stressor improved statistically insignificantly compared to the values obtained before.

CONCLUSION

This article shows the effect of EGG neurofeedback on reducing the negative effects of stress exposure in humans. The study showed that the level and a pattern of EEG neurofeedback influence and significance is different depending on the applied stressor. Furthermore, the level of EEG neurofeedback influence and significance in decreasing the stressor effect is different depending on the examined sphere.

Social isolation, loneliness, and the risk of incident acute kidney injury in middle-aged and older adults: A prospective cohort study

OBJECTIVE

The relationships of social isolation and loneliness with acute kidney injury (AKI) risk remained uncertain. We aimed to investigate the associations of social isolation and loneliness with incident AKI.

METHODS

450,868 participants without prior AKI were included from the UK Biobank. The social isolation index was constructed based on living alone, social contact, and participation in social activities. Loneliness was assessed by asking about "Do you often feel lonely?". The study outcome was incident AKI.

RESULTS

During a median follow-up of 12.0 years, 18,679 (4.1%) participants developed AKI, including 18,428 participants ascertained by hospital admission records with a median duration of hospitalization of 3 (25th-75th, 1-8) days. The hazard ratio for incident AKI for social isolation compared with no social isolation was 1.50 (95% CI: 1.44-1.55) after adjusting for age and race (minimally adjusted), and was 1.10 (95% CI: 1.06-1.14) after further adjusting for socioeconomic factors, health behaviors, biological and health-related factors, psychologic factors, and loneliness (fully adjusted). The minimally adjusted and fully adjusted hazard ratios for incident AKI for loneliness compared with no loneliness was 1.57 (95% CI: 1.52-1.62), and 1.10 (95% CI: 1.06-1.15), respectively. In the fully adjusted models, the highest risk of AKI was found in those with both social isolation and loneliness. Living alone and less social contact, rather than less participation in social activities, were significantly associated with a higher risk of incident AKI.

CONCLUSIONS

Both social isolation and loneliness were independently and significantly associated with a higher risk of incident AKI.

Psychological and neurobiological mechanisms involved in the relationship between loneliness and cognitive decline in older adults

Loneliness, among older adults, is one of the risk factors for developing dementia. Still, little is known about the neurobiological and psychological conditions that link loneliness to cognitive decline. The current study investigated several research aims: First, it sought to identify neurobiological and psychological pathways that may account for the relationship between loneliness and decline across several cognitive domains. These pathways included depressive symptoms, total gray matter volume, and conditional analyses of pro-inflammatory cytokines and brain-derived neurotrophic factor (BDNF) expression. Second, it examined loneliness as a predictor of mild cognitive impairment (MCI) and Alzheimer's disease (AD). Third, it sought to determine whether the relationship between loneliness and cognitive decline is sex-specific in older adults. Longitudinal data were collected from 2130 Rush Memory and Aging Project participants. Participants underwent annual cognitive and psychological assessments and neuroimaging procedures every year. BDNF gene expression was measured in the dorsolateral prefrontal cortex, cytokines were measured in serum, and the final consensus clinical diagnosis was identified at the time of death. All linear mixed and multinomial logistic regression models controlled for age at baseline, education, sex, and APOE genotype. Participants were largely women (73 %), and Caucasian (93 %). The average education was 14.93 (SD = 3.34). The average age at baseline was 80.05 (SD = 7.57). Results showed that gray matter volume and depressive symptoms partially mediated the relationship between loneliness and cognitive decline. There was a significant interaction between loneliness and BDNF expression in relation to cognitive decline. Higher levels of BDNF expression was associated with slower decline in semantic memory and visuospatial ability. Finally, the current study also established that higher levels of loneliness was positively associated with the incidence of AD and other dementias. The present findings support the growing literature, which tends to show that the consequence of loneliness goes beyond the feeling of being isolated. Loneliness may induce physiological changes in our brains, leading to cognitive decline. Future research can explore a wide range of biological and psychological expressions of loneliness to clarify how loneliness relates to dementia.

The association between depression and the cortisol awakening response is moderated by loneliness in men from a non-clinical sample

Previous studies investigating cortisol levels in people with depression or depressive symptoms have provided mixed findings. It has been suggested that the difficulty to generalize findings across studies in this field might be related to interindividual variability in experiencing depressive symptoms in terms of clinical and social contexts. Therefore, in the present study we aimed to test the association of morning cortisol levels and depressive symptoms in a non-clinical sample of young men taking into consideration the level of perceived loneliness. We hypothesized that the level of loneliness might moderate the association between morning cortisol levels and depressive symptoms. A total of 102 participants (aged 29.9 ± 5.0 years) completed questionnaires measuring the levels of depressive and anxiety symptoms, perceived stress, and loneliness. Cortisol levels were determined in four morning samples of saliva. There were significant positive correlations of the cortisol awakening response (CAR) and the mean increase in cortisol levels during the measurement period (MnInc) with the levels of depressive symptoms and loneliness. Moreover, a significant association of the depressive symptoms by loneliness interaction with the CAR and the MnInc was found. Specifically, the correlation of depressive symptoms with the CAR and the MnInc appeared to be significant and negative at high levels of loneliness. No significant association between depressive symptoms and the CAR was observed in men with low levels of loneliness. There were no significant associations of depressive symptoms, loneliness and the depressive symptoms by loneliness interaction with cortisol levels at awakening. In conclusion, findings from the present study indicate the importance of social contexts in understanding the association between altered activity of the hypothalamic-pituitary-adrenal axis and depressive symptoms in men.

Impact of social distancing from the COVID-19 pandemic on the immuno-inflammatory response of older adults

BACKGROUND

Older adults, as the population considered at increased risk for severe COVID-19, were the most impacted by social isolation. Thus, this study aimed to assess the salivary immune/inflammatory response of older adults before and during the COVID-19 pandemic.

METHODS

A cohort of 11 older adults (mean age 66.8 ± 6.1) was followed at three different time points: before (S1) and after 6 (S2) and 20 months (S3) of the beginning of the COVID-19 pandemic in Brazil. Unstimulated saliva samples were obtained to assess the levels of antibodies (secretory IgA, IgG and IgM) by ELISA and cytokines (IL-2, IL-5, IL-6, IL-8 and IL-10, TSLP, IFN-γ, TNF-α) by multiplex analysis. Significant differences were evaluated using the Kruskal-Wallis test with Dunn's post-test.

RESULTS

None volunteer presented periodontal disease or caries. All volunteers received at least two doses of the COVID-19 vaccines after S2 and before S3. A tendency to increase salivary levels of SIgA and IgM at S2 and of IgG at S3 were observed compared to the values found at S1 and S2. Significantly decreased levels of IL-2 and IL-5 were found at S2 and S3 (p < 0.001) time points. Lower levels of IFN-γ were found at S2 as compared to the values observed at S1 (p < 0.01). A significant decrease in the IFN-γ/IL-10 ratio was found at S2 (p < 0.01). When assessing the Th1/Th2 ratios, a significant decrease was found in the IFN-γ/TSLP ratio at S2 (p < 0.001) and S3 (p < 0.001) when compared to the values at S1. In addition, a significant increase was observed in the TNF-α/IL-5 ratio at S2 (p < 0.001) and S3 (p < 0.001) in comparison to the values at S1. In a similar way, an increase in the TNF-α/IL-6 ratio (Fig. 5E) was observed at S3 (p < 0.001) when compared to the values at S1.

CONCLUSIONS

Overall, this study provides valuable insights into the impact of COVID-19-induced social isolation on immune/inflammatory responses in the upper airway mucosa, particularly those present in oral cavity, of older adults. It demonstrates that a controlled shift in Th1 and Th2 immune responses, both during infection and post-vaccination, can create favorable conditions to combat viral infections without exacerbating the immune response or worsening the pathology.

Remotely-administered resilience and self-compassion intervention targeting loneliness and stress in older adults: a single-case experimental design

OBJECTIVES

Loneliness and chronic stress are prevalent issues for older adults that have been linked to adverse health outcomes. We conducted a remote resilience and self-compassion intervention targeting loneliness and chronic stress.

METHODS

This study utilized a multiple-phase-change single-case experimental design with three consecutive 6-week phases: control, intervention, follow-up. Assessments and biomarker collection (blood pressure, inflammation, sleep actigraphy) were conducted at each phase. Participants completed a 6-week remotely-administered resilience and self-compassion intervention using techniques from cognitive behavioral therapy and resilience training. Repeated measures ANOVAs were conducted over the 12-week period from control (week 0) to intervention completion (week 12) and over the 18-week period from control (week 0) to follow-up (week 18) in supplemental analyses.

RESULTS

Participants reported a reduction in stress (p < 0.001; ηp2 = 0.15), depression (p =  0.02; ηp2 = 0.08), and loneliness (p = 0.003; ηp2 = 0.18), and an increase in self-compassion (p  =  0.01; ηp2 = 0.13) from control to intervention completion (weeks 0-12). Post-hoc tests revealed that stress reduced significantly during the intervention phase (weeks 6-12) and loneliness reduced significantly during the control phase (weeks 0-6). Some improvements in blood pressure, inflammation, and sleep quality were noted in a subsample of participants.

CONCLUSION

Findings indicate that our remote resilience and self-compassion intervention for older adults targeting loneliness and chronic stress was efficacious.

Elevated Risk of Dementia Diagnosis in Older Adults with Low Frequencies and Durations of Social Conversation

Background

Social networks and social participation have protective effects on cognitive function maintenance and Alzheimer's disease and general dementia development.

Objective

We aimed to investigate the association between conversations and dementia incidence in older adults.

Methods

This longitudinal prospective cohort study used population data from the National Center for Geriatric and Gerontology-Study of Geriatric Syndromes (NCGG-SGS) from September 2015 to February 2017. The database included 4,167 individuals in Japan aged ≥60 years who were generally healthy and without major cognitive impairment. Participants were classified into two groups according to six daily conversation measures at baseline. The conversation index was calculated as a composite score for these measures. Participants were tracked monthly over 60 months for new-onset dementia.

Results

Data from 2,531 participants were analyzed (72.7±6.7 years; range: 60-96 years). Dementia incidence per 1,000 person-years was 15.7 (95% confidence interval, 13.6-18.1). The Youden index determined the cut-off point for dementia incidence, with a conversation index of 16/17 points. The low conversation group included more participants with new-onset dementia. Cox proportional hazards regression crude models showed remarkable relationships between dementia onset and specific conversation measurements, including conversation index. According to the Cox regression adjusted model, the cut-off point of the conversation index showed only a remarkable relationship with dementia onset.

Conclusions

Dementia risk was extensively associated with low daily conversation statuses. The assessment of conversational factors may be useful as a risk indicator for the development of Alzheimer's disease and general dementia.

The pandemic and social experience: For whom did discrimination and social isolation increase?

OBJECTIVE

The objective of this study was to examine whether experiences of discrimination have increased during the pandemic, particularly among negatively stigmatized racial/ethnic groups, and whether such experiences have exacerbated feelings of social isolation.

METHOD

Discrimination and social isolation were assessed before and during the pandemic in a sample of 263 Black and White young adults attending a large, predominantly White 4-year research university in the Southeastern region of the United States (52% Black, 48% White, 53% female, mean age = 19.2).

RESULTS

Increases in discrimination were evident among Black but not White participants. Black participants also reported greater increases in social isolation than White participants, and changes in discrimination partially mediated the emergent racial disparity in social isolation.

CONCLUSIONS

Findings are consistent with theoretical perspectives on discrimination during times of stress and suggest the need for broader attention to the impact of the pandemic on unfair treatment of stigmatized groups. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Do Social Support and Loneliness Influence Emerging Adults' Mental Health during the First Year of the COVID-19 Pandemic?

Youths' mental health is at a crisis level, with mental health problems doubling in the US since the pandemic began. To compound the mental health crisis, there is a global loneliness epidemic, with emerging adults worldwide experiencing some of the highest rates. One study with two phases examined the influence of social support and loneliness on mental health in US emerging adults during the pandemic, including changes in these relationships over one year. Emerging adults (N = 449) completed online questionnaires via Prolific in May 2020 (Phase 1) and again from January to May 2021 (N = 253; Phase 2). More perceived support was related to reduced loneliness, with family support having the most significant influence. Loneliness mediated the link between perceived support and adverse health outcomes. Higher loneliness predicted more perceived stress and sleep difficulties concurrently and over time. There was a bidirectional relationship between loneliness and depression, such that higher levels of either variable at Time 1 predicted increases in the other over time. Results highlight the detrimental impact of loneliness on emerging adults' mental health.

Psycho-social and health predictors of loneliness in older primary care patients and mediating mechanisms linking comorbidities and loneliness

BACKGROUND

Aging is associated with many personal, social, and environmental challenges that increase the risk of loneliness. Loneliness is a painful emotional experience associated with a perceived lack of connection and intimacy. Loneliness accelerates health deterioration, but the presence of chronic health conditions (comorbidities) in older individuals may potentiate the feeling of loneliness. The relationships between health status and loneliness in older individuals have not been assessed in an integrated manner, although it is necessary for planning efficient interventions. The aim of this study was to fill in this knowledge gap, by attempting to create an integrated model of loneliness in older individuals.

METHODS

The sample consisted of 189 (58% F) older individuals (> 60 years) (mean ± SD, 78.47 ± 6.65), attendees in Primary Health Care. Different factors associated with loneliness in the older population were assessed, and classified as demographic, environmental, physical (health-related), and psychological, in addition to functional abilities. A set of standard questionnaires was used to assess psychological factors and functional abilities. The hierarchical regression model assessed the effect of particular blocks of factors on status loneliness. The second aim was to analyze how psychological factors mediate associations between health status (comorbidity level) and loneliness.

RESULTS

Indicated that increasing comorbidity, anxiety, lack of positive moods, not having hobbies/activities, low perception of social support, impaired cognitive function, and suppression of emotion expression, are significant predictors of loneliness. Mediation analysis informed us of how to help patients with comorbidities feel less lonely. Interventions that were suggested were those that can reduce anxiety and depression, improve cognitive abilities and emotional regulation control, and enhance social support.

CONCLUSIONS

Results can help understand the pathophysiology loops linking poor health status (comorbidity level) of older individuals and loneliness, and have significant potentials from the translational perspectives, as a decision-support tool.

Unfavorable transcriptome profiles and social disadvantage in hematopoietic cell transplantation: a CIBMTR analysis

Patient-reported outcomes (PROs) capture subjective social determinants of health (SDOHs), which can affect health outcomes through the stress response pathway. The conserved transcriptional response to adversity (CTRA) is a stress-mediated proinflammatory transcriptomic pattern that has been linked to adverse hematopoietic cell transplant (HCT) outcomes. This study examined the association of pretransplant CTRA with patient-reported SDOHs in allogeneic HCT recipients. In this cross-sectional study, pre-HCT SDOH-related PROs included the 36-Item Short Form Health Survey and the Functional Assessment of Cancer Therapy-Bone Marrow Transplant (FACT-BMT). CTRA was assessed by RNA sequencing of whole blood specimens, with mixed effects linear regression models relating CTRA expression to PRO scores while controlling for age, sex, race, disease, and performance status. Among 121 patients, the median age was 54 years, 42% were female, and 91% were White. CTRA was elevated in participants reporting lower scores on the FACT-BMT (P = .003), including the general (P = .003) and BMT-specific (P = .014) components. Effects were driven by the social well-being domain (P = .0001). This corresponded to an 8% to 15% difference in CTRA RNA expression across a 4 standard deviation range in patient-reported SDOHs. Ancillary bioinformatics analyses confirmed the association of well-being with reduced proinflammatory transcription pathway activity [cyclic AMP response element-binding protein, (CREB), NF-κB, and activating protein-1 (AP-1)]. In conclusion, HCT-treated patients who experience unfavorable social conditions show elevated CTRA expression in pretransplant blood samples. These data highlight the biologic sequelae of social well-being and community context and suggest a potential molecular mechanism for the impact of social gradients in HCT outcomes. Targeting this pathway could optimize outcomes in this high-risk population.

The Association of Loneliness with Diabetes Is Mediated by Physical Activity and BMI but Not Diet Quality

Loneliness is considered a predictor of poor health through numerous pathways. Mediators of this association has not been extensively explored. The study objective was to determine if diet quality and physical activity are parallel mediators with body mass index (BMI) as the third mediator in the association of loneliness with diabetes. The sample, middle-aged and older African American and White adults, 36-77 years, participated in the second follow-up wave of the prospective Healthy Aging in Neighborhoods of Diversity across the Life Span study, 2013-2017. Loneliness was measured by the UCLA 3-item loneliness scale. Participants were categorized as not diabetic, pre-diabetic, or diabetic based on fasting blood glucose, self-reports, or taking medication for diabetes. The Mean Healthy Eating Index-2010 score was calculated from two 24 h dietary recalls collected using the USDA automated multiple pass method. Physical activity was derived from the Baecke questionnaire. The Hayes PROCESS macro, model #80, was used to perform the mediational analysis. Covariates were age, sex at birth, race, income, alcohol intake, and education. Loneliness was inversely and significantly associated with diet quality and physical activity. The only significant indirect path was loneliness > physical activity > BMI > diabetes. Better understanding of modifiable lifestyle behaviors when developing interventions may improve mental health, thereby improving health.

Loneliness and Risk of Parkinson Disease

Importance

Loneliness is associated with morbidity and mortality, including higher risk of neurodegenerative diseases. To our knowledge, no study has examined whether the association between loneliness and detrimental outcomes extends to Parkinson disease (PD).

Objective

To assess whether loneliness is associated with risk of incident PD and whether the association is independent of other risk factors or modified by age, sex, and genetic vulnerability.

Design, Setting, and Participants

This prospective cohort study included a population-based sample of UK Biobank participants aged 38 to 73 years with loneliness data and without a diagnosis of PD at baseline who were first assessed from March 13, 2006, to October 1, 2010, and followed up to October 9, 2021.

Exposure

Feeling lonely and covariates that are known risk factors for or prodromal features of PD.

Main Outcome and Measure

Incident PD was ascertained through UK National Health Service health records.

Results

Of 491 603 participants (mean [SD] age, 56.54 [8.09] years; 54.4% female), 2822 developed PD during the 15-year follow-up. Individuals who reported being lonely had a higher risk of PD (hazard ratio [HR], 1.37; 95% CI, 1.25-1.51), an association that remained after accounting for demographic factors, socioeconomic status, social isolation, PD polygenetic risk score, smoking, physical activity, body mass index, diabetes, hypertension, stroke, myocardial infarction, depression, and ever seeing a psychiatrist (fully adjusted model: HR 1.25; 95% CI, 1.12-1.39). The association between loneliness and incident PD was not moderated by sex (HR for interaction, 0.98; 95% CI, 95% CI, 0.81-1.18), age (HR for interaction, 0.99; 95% CI, 0.98-1.01), or polygenic risk score (HR for interaction, 0.93; 95% CI, 0.85-1.02). Contrary to expectations for a prodromal syndrome, when stratified by time, loneliness was not associated with risk for incident PD during the first 5 years (HR, 1.15; 95% CI, 0.91-1.45) but was associated with PD risk during the subsequent 10 years (HR, 1.32; 95% CI, 1.19-1.46).

Conclusions and Relevance

This large cohort study found that loneliness was associated with risk of incident PD across demographic groups and independent of depression and other prominent risk factors and genetic risk. The findings add to the evidence that loneliness is a substantial psychosocial determinant of health.

Relationship of Chronic Systemic Inflammation to Both Chronic Lifestyle-Related Diseases and Osteoarthritis: The Case for Lifestyle Medicine for Osteoarthritis

Systemic inflammation is a root cause of lifestyle-related chronic diseases and may also play a role in the development and progression of osteoarthritis (OA). Lifestyle medicine seeks to treat, prevent, and reverse lifestyle-related chronic disease via 6 pillars: nutrition, sleep health, stress management, physical activity, social connections, and risky behavior avoidance/reduction. This article presents a review of the literature in which we assess the connections between the 6 pillars of lifestyle medicine, chronic systemic inflammation, and OA. We also discuss the whole-person approach that lifestyle medicine interventions can provide to reduce chronic systemic inflammation and affect the development or progression of OA.

The heart of Detroit study: a window into urban middle-aged and older African Americans' daily lives to understand psychosocial determinants of cardiovascular disease risk

BACKGROUND

Cardiovascular disease disproportionately affects African Americans. Psychosocial factors, including the experience of and emotional reactivity to racism and interpersonal stressors, contribute to the etiology and progression of cardiovascular disease through effects on health behaviors, stress-responsive neuroendocrine axes, and immune processes. The full pathway and complexities of these associations remain underexamined in African Americans. The Heart of Detroit Study aims to identify and model the biopsychosocial pathways that influence cardiovascular disease risk in a sample of urban middle-aged and older African American adults.

METHODS

The proposed sample will be composed of 500 African American adults between the ages of 55 and 75 from the Detroit urban area. This longitudinal study will consist of two waves of data collection, two years apart. Biomarkers of stress, inflammation, and cardiovascular surrogate endpoints (i.e., heart rate variability and blood pressure) will be collected at each wave. Ecological momentary assessments will characterize momentary and daily experiences of stress, affect, and health behaviors during the first wave. A proposed subsample of 60 individuals will also complete an in-depth qualitative interview to contextualize quantitative results. The central hypothesis of this project is that interpersonal stressors predict poor cardiovascular outcomes, cumulative physiological stress, poor sleep, and inflammation by altering daily affect, daily health behaviors, and daily physiological stress.

DISCUSSION

This study will provide insight into the biopsychosocial pathways through which experiences of stress and discrimination increase cardiovascular disease risk over micro and macro time scales among urban African American adults. Its discoveries will guide the design of future contextualized, time-sensitive, and culturally tailored behavioral interventions to reduce racial disparities in cardiovascular disease risk.

Perceived Social Support and Sustained Physical Activity During the COVID-19 Pandemic

BACKGROUND

COVID-19 lockdown introduced substantial barriers to physical activity, providing a unique 'natural experiment' to understand the social factors associated with sustained physical activity. The objectives of this study were to identify the proportion of people who successfully sustained physical activity during lockdown and to explore whether social support, loneliness and social isolation were associated with maintenance of physical activity during COVID-19 lockdown.

METHOD

Longitudinal data from 16,980 participants, mean age 51.3 years (SD = 14.3) from the COVID-19 Social Study was used to identify a sample of participants who maintained their physical activity despite lockdown.

RESULTS

Seventeen percent were consistently active whilst 42% were completely inactive. After adjustment for multiple confounders, high social support was associated with a 64% (95% CI 50-80%) increased odds of sustaining physical activity and medium social support was associated with 32% (95% CI 20-44%) increased odds. Associations between physical activity and loneliness and social isolation were not found.

CONCLUSION

This study supports previous research showing the importance of social support for the long-term maintenance of physical activity behaviour but shows that such effects extend to contexts of social restrictions.

Combined effects of loneliness and inflammation on depression in people with HIV

OBJECTIVE

Loneliness is prevalent in people with HIV (PWH) and associated with adverse health-related consequences, including depression. Chronic inflammation has been linked to depression in PWH, though its association with loneliness is less well established. Simultaneous examination of inflammation, loneliness and depression is needed to clarify these relationships. This study investigated the relationship between loneliness and inflammation, and the effects of loneliness and inflammation on depression in PWH.

METHODS

82 PWH who were on suppressive ART (mean age [SD] = 53.2 [9.0]) completed the UCLA Loneliness Scale-Version 3 and the Center for Epidemiologic Studies Depression Scale as part of a comprehensive evaluation. Biomarkers of systemic inflammation (CRP, IL-6, CCL2/MCP-1, sCD14) and coagulation (D-dimer) were measured in blood using commercial immunoassays.

RESULTS

Multivariable linear regression analyses revealed that higher D-dimer, CCL2/MCP-1, and sCD14 were significant predictors of loneliness (ps < .05) while accounting for relevant covariates. Stepwise multiple linear regression models that included loneliness, biomarkers, and their interactions as predictors of depressive symptoms revealed significant main effects of loneliness and CCL2/MCP-1 levels (ps < .05), and a significant loneliness by D-dimer interaction (p < .05) whereby higher D-dimer was associated with increased depressive symptoms only at higher levels of loneliness.

CONCLUSIONS

Increased coagulation activity is associated with loneliness, and in the context of loneliness, may increase risk for depression. Increased inflammation was associated with depression suggesting potentially dissociable underlying biological processes. To the extent that these processes are modifiable, such findings could have important implications in the treatment of loneliness and depression in PWH.

How does loneliness "get under the skin" to become biologically embedded?

Loneliness is linked to declining physical health across cardiovascular, inflammatory, metabolic, and cognitive domains. As a result, loneliness is increasingly being recognized as a public health threat, though the mechanisms that have been studied do not yet explain all loneliness-related health risk. Potential mechanisms include loneliness having 1.) direct, causal impacts on health, possibly maintained by epigenetic modification, 2.) indirect effects mediated through health-limiting behaviors, and 3.) artifactual associations perhaps related to genetic overlap and reverse causation. In this scoping review, we examine the evidence surrounding each of these pathways, with a particular emphasis on emerging research on epigenetic effects, in order to evaluate how loneliness becomes biologically embedded. We conclude that there are significant gaps in our knowledge of how psychosocial stress may lead to physiological changes, so more work is needed to understand if, how, and when loneliness has a direct influence on health. Hypothalamic-pituitary adrenocortical axis disruptions that lead to changes in gene expression through methylation and the activity of transcription factor proteins are one promising area of research but are confounded by a number of unmeasured factors. Therefore, wok is needed using causally informative designs, such as twin and family studies and intensively longitudinal diary studies.