Challenges in replication: Does amygdala gray matter volume relate to social network size?

In this work, we tried to replicate and extend prior research on the relationship between social network size and the volume of the amygdala. We focused on the earliest evidence for this relationship (Bickart et al., Nature Neuroscience 14(2), 163-164, 2011) and another methodologically unique study that often is cited as a replication (Kanai et al., Proceedings of the Royal Society B: Biological Sciences, 279(1732), 1327-1334, 2012). Despite their tight link in the literature, we argue that Kanai et al. (Proceedings of the Royal Society B: Biological Sciences, 279(1732), 1327-1334, 2012) is not a replication of Bickart et al. Nature Neuroscience 14(2), 163-164 (2011), because it uses different morphometric measurements. We collected data from 128 participants on a 7-Tesla MRI and examined variations in gray matter volume (GMV) in the amygdala and its nuclei. We found inconclusive support for a correlation between measures of real-world social network and amygdala GMV, with small effect sizes and only anecdotal evidence for a positive relationship. We found support for the absence of a correlation between measures of online social network and amygdala GMV. We discuss different challenges faced in replication attempts for small effects, as initially reported in these two studies, and suggest that the results would be most helpful in the context of estimation and future meta-analytical efforts. Our findings underscore the value of a narrow approach in replication of brain-behavior relationships, one that is focused enough to investigate the specifics of what is measured. This approach can provide a complementary perspective to the more popular "thematic" alternative, in which conclusions are often broader but where conclusions may become disconnected from the evidence.

Social network size moderates the association between loneliness and cardiovascular reactivity to acute stress.

Loneliness and objective measures of social isolation (e.g., social network size) have been associated with increased risk of cardiovascular disease (CVD). However, the evidence is mixed and the precise causal mechanisms remain unclear. Cardiovascular reactivity (CVR) to acute stress has been posited as a proposed mechanism. This study aimed to investigate: (i) effects of loneliness and social isolation on CVR to stress and, (ii) whether the loneliness - CVR relationship was moderated by social network size. Two hundred and six participants from the Pittsburgh Cold Study underwent a modified version of the Trier Social Stress Task. Cardiovascular measures of systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) were taken throughout the laboratory stress trial. Hierarchical regression analyses found that social network size was positively associated with DBP reactivity (ß = 0.19 95 % CI [0.05, 0.29] p = 0.005), while loneliness was not. In addition, social network size moderated the loneliness - DBP reactivity relationship such that a higher number of outer social network ties were beneficial at lower levels of loneliness but not higher. The current study contributes new evidence linking loneliness and social network size to cardiovascular psychophysiology but raises questions about the loneliness - CVD relationship. The findings confirm the importance of social network size and highlight that the characteristics of the networks may be more important than the number of networks.

Loneliness Is Associated With Lower Self- and Clinician-Rated Levels of Personality Functioning.

Personality disorders (PDs) are associated with interpersonal dysfunction, loneliness, and reduced social embeddedness. This study investigates loneliness and social network size in association with self- and clinician-rated personality functioning regarding the DSM-5's Alternative Model for Personality Disorders (AMPD). Eighty psychiatric inpatients including participants with and without PDs completed the Semi-structured Interview for Personality Functioning, the Level of Personality Functioning Scale - Brief Form, the UCLA Loneliness Scale, and the Social Network Index. Patients with PDs reported more loneliness and personality dysfunctioning than patients without PDs. Social network size did not differ between patient groups and showed lower correlations with personality functioning compared to loneliness. Loneliness was further associated with deficits in personality functioning. Deficits in distinct AMPD domains and loneliness may constitute transdiagnostically relevant factors that are related and mutually reinforcing. This could be important for identifying patients beyond PD diagnoses who are at risk of poor psychosocial functioning and require tailored psychotherapy.

Testing the Reciprocal Relationship Between Social Networks and Purpose in Life Among Older Adults: Application of a Random Intercept Cross-Lagged Panel Model.

Objectives: The purpose of this study is to examine if there are longitudinal reciprocal effects between social network size and purpose in life among older adults. Methods: Using data from the National Health and Aging Trends Study, the sample included 1485 male and 2058 female adults 65 years and older. We first computed t-tests to assess gender differences in social network size and purpose in life. In order to examine the reciprocal effects between social network size and purpose in life over four time points (2017, 2018, 2019, and 2020), a RI-CLPM (Model 1) was computed. In addition to the main model, two multiple group RI-CLPM analyses (Model 2 and 3) were computed to test the moderated gender effect on the relationship with models estimating unconstrained and constrained cross-lagged parameters. Results: The results of the t-tests denoted significant gender differences in social network size and purpose in life. The results indicated that Model 1 fit the data well. The carry-over effects of social networks and purpose in life and spill-over effect from wave 3 purpose in life on wave 4 social networks were significant. There were no significant differences between the constrained and unconstrained models testing for moderated gender effects. Discussion: The findings of the study highlight the significant carry-over effect of purpose in life and social network size over four years and the positive spill-over effect from purpose in life on social network size at the subsequent wave, which only appeared at the last time point.

Frequency and Correlates of Multimorbidity Among the Oldest Old: Study Findings from the Representative "Survey on Quality of Life and Subjective Well-Being of the Very Old in North Rhine-Westphalia (NRW80+)".

Purpose: Our aim was to clarify the frequency and correlates of multimorbidity among the oldest old. Patients and Methods: We used data from the representative "Survey on quality of life and subjective well-being of the very old in North Rhine-Westphalia (NRW80+)" covering participants ≥80 years living in private households and in institutionalized settings in North Rhine-Westphalia (n = 1484, mean age was 86.3 years). Multimorbidity is defined as the co-occurrence of at least two chronic conditions. Sociodemographic, lifestyle-related, and health-related (including health literacy) correlates were included in regression analysis. Results: About 79% of the participants were multimorbid. Logistic regressions showed that the likelihood of multimorbidity significantly increased with living in a private household, having a larger network size, worse self-rated health, higher functional impairment, and more depressive symptoms, whereas the remaining sociodemographic and lifestyle-related factors as well as health literacy were not significantly associated with multimorbidity. Conclusion: A large proportion of participants in very late life is multimorbid. Apart from health-related factors, also two sociodemographic factors (ie, living situation and network size) were associated with multimorbidity among the oldest old. This knowledge may help to identify individuals at risk for multimorbidity in very late life.

Social network size and its relationship to domains of quality-of-life among older persons living with HIV.

Gerontological research suggests that social network characteristics are key elements of successful aging as they are related to a positive quality-of-life (QoL). Less is known about the social networks of persons aging with HIV. To describe social network characteristics and assess the effect of social network size on QoL, a sample of 146 OPWH (age ≥50) was recruited from an outpatient HIV clinic in Atlanta, GA. Social network size was assessed using Cohen's social network index (SNI). Domains of QoL (physical, emotional, and social) were assessed using the RAND-36. Descriptive analyses were used to determine the frequency of contact within social networks and multivariable regression models were used to assess the relationship between SNI and three domains of QoL controlling for potential covariates. Participants were predominantly male (60%), heterosexual (63%), and African American (86%). Regular contact occurred most frequently with friends (82%) and relatives (77%). Multivariable modeling revealed that SNI explained 58% of the variance in emotional QoL (R2 = 0.58, F(8, 137) = 25.48, p < .001). Findings provide basis for potential interventions focused on the specific social network to improve emotional QoL of this vulnerable population.

The Interplay of Personality Traits and Social Network Characteristics in the Subjective Well-Being of Older Adults.

Using data from the Survey of Health, Ageing and Retirement in Europe, we regressed three well-being measures (CASP, life satisfaction and Euro-D depressive symptoms) on indicators of personality and social network. Personality was indicated by the Big-Five personality traits, while social network was measured in terms of size, contact frequency and emotional closeness. The analysis also considered personality-network interactions, controlling for confounders. The sample was comprised of 35,145 adults, aged 50 and older, from 24 European countries and Israel. The results revealed that the personality traits explained more variance in the well-being outcomes than the social network characteristics did. However, the interactions showed that the social network characteristics, particularly size and mean emotional closeness, offset the effects of dysfunctional personality attributes on subjective well-being in late life. Hence, social network characteristics were shown to modify the potentially ill effects of personality on key well-being indicators.

Changes in structure and function of social networks of independently living middle-aged and older adults in diverse sociodemographic subgroups during the COVID-19 pandemic: a longitudinal study.

BACKGROUND: Social networks, i.e., all social relationships that people have, contribute to well-being and health. Governmental measures against COVID-19 were explicitly aimed to decrease physical social contact. We evaluated ego-centric social network structure and function, and changes therein, among various sociodemographic subgroups before and during the COVID-19 pandemic. METHODS: Independently living Dutch adults aged 40 years and older participating in the SaNAE longitudinal cohort study filled in online questionnaires in 2019 and 2020. Changes in network size (network structure) and social supporters (network function) were assessed. Associations with risk for changes (versus stable) were assessed for sociodemographic subgroups (sex, age, educational level, and urbanization level) using multivariable regression analyses, adjusted for confounders. RESULTS: Of 3,344 respondents 55% were men with a mean age of 65 years (age range 41-95 in 2020). In all assessed sociodemographic subgroups, decreases were observed in mean network size (total population: 11.4 to 9.8), the number of emotional supporters (7.2 to 6.1), and practical supporters (2.2 to 1.8), and an increase in the number of informational supporters (4.1 to 4.7). In all subgroups, the networks changed to being more family oriented. Some individuals increased their network size or number of supporters; they were more often women, higher-educated, or living in rural areas. CONCLUSION: The COVID-19 pandemic impacted social networks of people aged 40 years and older, as they increased informational support and reduced the number of their social relationships, mainly in terms of emotional and practical supporters. Notably, some individuals did not show such unfavorable trends and managed to reorganize their networks to attribute social support roles more centrally.

Data for the link between HEXACO personality traits and job search outcomes in Vietnam.

The purpose of this research data is to mention a correlation matrix of data-analytic estimates between the HEXACO personality traits and number of job interviews and job offers through job search networking behavior. The data-analytic correlations are based on 773 graduated students in universities in the North of Vietnam. This data used self-report surveys to collect the data. The data was analyzed using the AMOS software version 22. The obtained data indicated that the level of networking behavior positively affects both number of job interviews and job offers of individuals. Moreover, the acquired data revealed that the personality traits of honesty-humility, extraversion, agreeableness, conscientiousness, and openness to experience are positively related to the level of networking behavior, while emotionality is negatively associated with networking intensity.

Association of social network properties with resilience and depression among community-based Korean population.

We aimed to determine how the properties of social networks relate to resilient-related status. This cross-sectional study used baseline data from the Cardiovascular and Metabolic Disease Etiology Research Center cohort and included 11,132 participants. Ego-centric social network size and intimacy were used to reflect social network properties. Resilient-related status was operationally defined based on the participant's response to the Life Experience Survey and the Back Depression Inventory Ⅱ. Participants were categorized into three groups: reference (no negative life event; no depression), resilient (with negative life event; but no depression), and depression (no/with negative life event; with depression). Multinomial logistic regression models were used to estimate the association of social networks on the resilient-related status after adjusting for all covariates. Social network size was positively associated with the resilient group for both sex (male: OR = 1.01 [95% CI = 0.96 to 1.05], female: OR = 1.07 [95% CI = 1.03 to 1.11]), whereas intimacy showed a negative association (male: OR = 0.91 [95% CI = 0.82 to 1.01], female: OR = 0.84 [95% CI = 0.76 to 0.92]). Additionally, as each social network property increased, the likelihood of being categorized as belonging to the depression group decreased, regardless of age and sex.

Minimum spanning tree analysis of brain networks: A systematic review of network size effects, sensitivity for neuropsychiatric pathology, and disorder specificity.

Brain network characteristics' potential to serve as a neurological and psychiatric pathology biomarker has been hampered by the so-called thresholding problem. The minimum spanning tree (MST) is increasingly applied to overcome this problem. It is yet unknown whether this approach leads to more consistent findings across studies and converging outcomes of either disease-specific biomarkers or transdiagnostic effects. We performed a systematic review on MST analysis in neurophysiological and neuroimaging studies (N = 43) to study consistency of MST metrics between different network sizes and assessed disease specificity and transdiagnostic sensitivity of MST metrics for neurological and psychiatric conditions. Analysis of data from control groups (12 studies) showed that MST leaf fraction but not diameter decreased with increasing network size. Studies showed a broad range in metric values, suggesting that specific processing pipelines affect MST topology. Contradicting findings remain in the inconclusive literature of MST brain network studies, but some trends were seen: (1) a more linelike organization characterizes neurodegenerative disorders across pathologies, and is associated with symptom severity and disease progression; (2) neurophysiological studies in epilepsy show frequency band specific MST alterations that normalize after successful treatment; and (3) less efficient MST topology in alpha band is found across disorders associated with attention impairments.

Association Between Social Network and Cognitive Function: A Cross-Sectional Assessment From the Cardiovascular and Metabolic Diseases Etiology Research Center Cohort (2013-2018).

Background: This study aimed to investigate how social networks are associated with cognitive function in the middle-aged and elderly Korean population. Methods: A total of 7,704 individuals over the age of 50 were included from the baseline recruitment of the Cardiovascular and Metabolic Diseases Etiology Research Center cohort from the years 2013 to 2018. Egocentric social network characteristics including network size, intimacy, and frequency of face-to-face meetings were measured as exposures, and the Korean version of Mini-Mental State Examination (K-MMSE) score was measured to reflect general cognitive function as an outcome. We also stratified the analysis by income level into tertiles, with income caps of 42,000 thousand won and 72,000 thousand won. A general linear regression model was used, adjusting for age, gender, socioeconomic factors, lifestyle factors, depressive symptoms, and study settings. Results: Social network properties were positively associated with cognitive function in both men and women. However, the specific estimates varied according to gender and income level. In men, frequency was most significantly associated with cognitive function (standardized ß = 0.093, p-value <0 .0001). In women, the strength of the association with cognitive function was found in size (standardized ß = 0.055, p-value = 0.001). The effect modification of income level could be seen in the association between frequency and cognitive function. The strongest association between frequency and cognitive function was found in the middle income group in men (standardized ß = 0.114, p-value = 0.0063), and the low income group in women (standardized ß = 0.076, p-value = 0.0039). Conclusion: There were positive associations between social network properties (i.e., size, intimacy, and frequency of face-to-face meetings) and cognitive function. The degree of association varied according to social network properties, gender, and income level. Overall, among social network properties, social network size was an important factor in the cognition of women, whereas frequency was important in the cognition of men.

How network size strongly determines trophic specialisation: A technical comment on Luna et al. (2022).

Luna et al. (2022) concluded that the environment contributes to explaining specialisation in open plant-pollinator networks. When reproducing their study, we instead found that network size alone largely explained the variation in their specialisation metrics. Thus, we question whether empirical network specialisation is driven by the environment.

Resting functional connectivity of the left inferior frontal gyrus with the dorsomedial prefrontal cortex and temporoparietal junction reflects the social network size for active interactions.

The size of an individual active social network is a key parameter of human social behavior and is correlated with subjective well-being. However, it remains unknown how the social network size of active interactions is represented in the brain. Here, we examined whether resting-state functional magnetic resonance imaging (fMRI) connectivity is associated with the social network size of active interactions using behavioral data of a large sample (N = 222) on Twitter. Region of interest (ROI)-to-ROI analysis, graph theory analysis, seed-based analysis, and decoding analysis together provided compelling evidence that people who have a large social network size of active interactions, as measured by "reply," show higher fMRI connectivity of the left inferior frontal gyrus with the dorsomedial prefrontal cortex and temporoparietal junction, which represents the core of the theory of mind network. These results demonstrated that people who have a large social network size of active interactions maintain activity of the identified functional connectivity in daily life, possibly providing a mechanism for efficient information transmission between the brain networks related to language and theory-of-mind.

Does personality shape the personal social networks of older Europeans?

The aim of the study was to clarify whether personality traits predict the structure, function and quality of egocentric confidant networks in later life. Data were drawn from Waves 7 and 8 of the Survey of Health, Ageing and Retirement in Europe (SHARE) (N = 39,172). We regressed network size, contact frequency and network satisfaction on the Big-5 personality traits, using a single path analysis structure, controlling for country, sociodemographic background and health status. The findings showed that the personality traits were related to the social network outcomes, but their effect was modest and less predictive than the contextual factors. The country predictors explained the most variance, generally, with some surprising results. For example, confidant networks were the largest in Scandinavia and Central Europe, and smallest in the Mediterranean region and Eastern Europe. Among the personality traits, extraversion was the most consistent positive predictor, but conscientiousness was also predictive. Neuroticism was a negative predictor, but not of network size. The sociodemographic variables, particularly partner status, explained more variance than the personality traits did. In sum, the SHARE database offers a comprehensive and differentiated view of the complex interpersonal milieus in which older Europeans are embedded. Supplementary Information: The online version contains supplementary material available at 10.1007/s10433-021-00678-8.

Behavioral and neural correlates of social network size: The unique and common contributions of face recognition and extraversion.

OBJECTIVES: Humans are inherently social creatures and can gain advantages from larger network size. Researches have shown that different cognitive and personality factors may result in individual differences of social network size (SNS). Here, we focused on whether face recognition ability and extraversion were related to SNS and the neural basis underlying the relations. METHODS: Behaviorally, we adopted the face-inversion task, NEO personality inventory, and computerized SNS test to explore the relationships between face recognition, extraversion, and SNS. Neurally, we used resting state functional magnetic resonance imaging and fractional amplitude of low-frequency fluctuation (fALFF) analysis method to investigate the neural correlates of SNS and then revealed whether face recognition and extraversion were related to SNS relevant brain regions. RESULTS: We found that individuals with better face recognition ability and more extraverted personality had larger size of social network. In addition, we found that SNS was positively associated with the fALFF in the ventromedial prefrontal cortex (vmPFC), right superior temporal sulcus, and precuneus. Interestingly, the fALFF in the vmPFC significantly correlated with face recognition ability. CONCLUSIONS: Our study suggests that both face recognition and extraversion may be important correlates of SNS, and the underlying spontaneous neural substrates are partially dissociable.

The Moderating Role of Social Network Size on Social Media Use and Self-Esteem: An Evolutionary Mismatch Perspective.

Existing meta-analyses have shown that the relationship between social media use and self-esteem is negative, but at very small effect sizes, suggesting the presence of moderators that change the relationship between social media use and self-esteem. Employing principles from social comparison and evolutionary mismatch theories, we propose that the social network sizes one has on social media play a key role in the relationship between social media use and self-esteem. In our study (N = 123), we showed that social media use was negatively related to self-esteem, but only when their social network size was within an evolutionarily familiar level. Social media use was not related to self-esteem when people's social networks were at evolutionarily novel sizes. The data supported both social comparison and evolutionary mismatch theories and elucidated the small effect size found for the relationship between social media use and self-esteem in current literature. More critically, the findings of this study highlight the need to consider evolutionarily novel stimuli that are present on social media to better understand the behaviors of people in this social environment.

The impact of social networks on sleep among a cohort of college students.

BACKGROUND: Sleep duration and quality are associated with physical and mental wellbeing. This paper examines social network effects on individual level change in the sleep quantity and quality from late adolescence to emerging adulthood and its associated factors, including the influence of peers on sleep behavior and the impact of changes in network size. METHODS: We use sleep data from 619 undergraduates at the University of Notre Dame obtained via Fitbit devices as part of the NetHealth project. The data were collected between August 16, 2015 and May 13, 2017. We model trends in sleep behaviors using latent growth-curve models. RESULTS: Controlling for the many factors known to impact sleep quantity and quality, we find two social network effects: increasing network size is associated with less sleep and a student's sleep levels are influenced by his or her peers. While we do not find any consistent decline in sleep quantity over the 637 days, daily fluctuations in sleep quantity are associated with changes in network size and the composition of a student's network. As a student's network gets bigger, s/he sleeps less, and when a student's contacts sleep more (or less) than s/he does, the student becomes more like his or her contacts and sleeps more (or less). CONCLUSIONS: Social networks can and do impact sleep, especially sleep quantity. In contexts where students want to have larger networks, the difficulties of increasing network size and maintaining larger networks negatively impact sleep. Because of peer influence, the effectiveness of interventions designed to improve sleep practices could be increased by leveraging student social networks to help diffuse better sleep habits.

Correlates of Alcohol-Using Network Size Among Men Who Have Sex with Men in San Francisco, CA.

Men who have sex with men (MSM) have a high prevalence of hazardous alcohol consumption. While network-level characteristics such as social network size have been indicated as upstream determinants of alcohol use in general population samples, no studies have examined factors associated with alcohol using network size (ANS), among MSM.This secondary analysis examined demographic, substance use, and sexual behavior correlates of ANS using data from a diverse sample of alcohol-using MSM in San Francisco (N = 252). Associations were calculated using multivariable negative binomial regression, adjusting for age, race, education, and employment.The median ANS was 10. Factors associated with larger ANS in multivariable analyses included identifying as Hispanic/Latino, having completed a college education or higher, having a higher Alcohol Use Disorders Identification Test (AUDIT) score, having a greater number of sexual partners, polysubstance use, and being unaware of one's own HIV status. Factors associated with smaller ANS included being between 18 and 24 years of age, reporting a low income, and having any lifetime history of injection drug use.For MSM, ANS was associated with increased likelihood of hazardous alcohol use, as well specific individual-level substance use and sexual risk behaviors. These results highlight the role of ANS in hazardous alcohol consumption and sexually transmitted infection transmission among MSM. These results also indicate ways that research and intervention programs aimed at reducing alcohol use among MSM might be improved through network-based recruitment or engagement. Finally, these results suggest the need for further research on HIV-unknown MSM.

Social connectedness and hair cortisol in community-dwelling older adults.

Purpose: Hair cortisol is emerging as a reliable biomarker for measuring retrospective stress hormone levels. Given that social connectedness can buffer psychobiological stress reactivity, increasing attention is being paid to the specific types of social networks associated with the stress response. This study investigated the role played by two components of social life, emotional closeness and network size, to probe which aspects of social networks were related to stress measures. Methods: The scalp hair cortisol level was used to assess the cumulative cortisol production in 179 community-dwelling older adults, in the Korean Social Life, Health, and Aging Project (KSHAP). Multivariate regression approach was used to examine the link between the stress measures (cortisol and perceived stress scale) and social relationships (social network size and emotional closeness). Results: Emotional closeness (the average level of what one feels about one's relationship) was significantly associated with decreased levels of hair cortisol, whereas no such relationship was found with the network size. Conclusions: The current findings underscore the role of emotional support on reducing cumulative cortisol, thus providing potential resilience mechanisms for the psychobiological stress response.