A Prospective Sociocentric Study of 2 Entire Traditional Korean Villages: The Korean Social Life, Health, and Aging Project (KSHAP).

The Korean Social Life, Health, and Aging Project (KSHAP) was a multidisciplinary prospective study conducted in South Korea that measured various health biomarkers from blood, hair, and brain magnetic resonance imaging, and we examined their associations with sociocentric (global) social network data of older adults in 2 entire villages (or cohorts). Cohort K included participants aged 60 years or older, and cohort L included participants aged 65 years or older. We performed a baseline survey involving 814 of the 860 individuals (94.7% response rate) in cohort K in 2012 and 947 of the 1,043 individuals (90.8% response rate) in cohort L in 2017. We gathered longitudinal data for 5 waves in cohort K from 2011 to 2019 and 2 waves in cohort L from 2017 to 2022. Here, we describe for the first time the follow-up design of the KSHAP, the changes in social networks, and various biomarkers over a number of years. The data for cohort K are publicly available via the Korean Social Science Data Archive as well as the project website, and the data for cohort L will be shared soon.

Similarity in functional brain connectivity at rest predicts interpersonal closeness in the social network of an entire village.

People often have the intuition that they are similar to their friends, yet evidence for homophily (being friends with similar others) based on self-reported personality is inconsistent. Functional connectomes-patterns of spontaneous synchronization across the brain-are stable within individuals and predict how people tend to think and behave. Thus, they may capture interindividual variability in latent traits that are particularly similar among friends but that might elude self-report. Here, we examined interpersonal similarity in functional connectivity at rest-that is, in the absence of external stimuli-and tested if functional connectome similarity is associated with proximity in a real-world social network. The social network of a remote village was reconstructed; a subset of residents underwent functional magnetic resonance imaging. Similarity in functional connectomes was positively related to social network proximity, particularly in the default mode network. Controlling for similarities in demographic and personality data (the Big Five personality traits) yielded similar results. Thus, functional connectomes may capture latent interpersonal similarities between friends that are not fully captured by commonly used demographic or personality measures. The localization of these results suggests how friends may be particularly similar to one another. Additionally, geographic proximity moderated the relationship between neural similarity and social network proximity, suggesting that such associations are particularly strong among people who live particularly close to one another. These findings suggest that social connectivity is reflected in signatures of brain functional connectivity, consistent with the common intuition that friends share similarities that go beyond, for example, demographic similarities.

Social Network Characteristics Predict Loneliness in Older Adults.

INTRODUCTION: Social isolation is detrimental to late-life health outcomes. Although objective social isolation is a major source of perceived loneliness, how different layers of social disconnection systematically constitute the subjective experience of loneliness remains unclear. METHODS: This study focused on older adults who participated in the Korean Social Life, Health, and Aging Project (KSHAP) (n = 1,724; mean age = 72.91 years) and examined how the proximal and distal characteristics of social networks predict loneliness using a hierarchical linear regression model. The study also investigated whether the major loss of social roles (marital and working status) influences perceived loneliness through the proximal and distal aspects of social networks by cross-sectional mediation analysis. RESULTS: This study found that the proximal (subjective number of connections) and distal (brokerage and embeddedness) aspects of social networks additively explained the frequency of loneliness. Moreover, the loss of late-life social roles (marital and working status) was related to an increase in loneliness, where the distal characteristic of social networks mediated this relationship. DISCUSSION/CONCLUSION: The results of this study suggest that the proximal and the distal characteristic of social networks is a social determinant predicting loneliness in late life. Besides, the loss of bridging and cohesive position among community networks may be a critical pathway to psychosocial transition after marital and working status changes.

Distributed functional connectivity predicts neuropsychological test performance among older adults.

Neuropsychological test is an essential tool in assessing cognitive and functional changes associated with late-life neurocognitive disorders. Despite the utility of the neuropsychological test, the brain-wide neural basis of the test performance remains unclear. Using the predictive modeling approach, we aimed to identify the optimal combination of functional connectivities that predicts neuropsychological test scores of novel individuals. Resting-state functional connectivity and neuropsychological tests included in the OASIS-3 dataset (n = 428) were used to train the predictive models, and the identified models were iteratively applied to the holdout internal test set (n = 216) and external test set (KSHAP, n = 151). We found that the connectivity-based predicted score tracked the actual behavioral test scores (r = 0.08-0.44). The predictive models utilizing most of the connectivity features showed better accuracy than those composed of focal connectivity features, suggesting that its neural basis is largely distributed across multiple brain systems. The discriminant and clinical validity of the predictive models were further assessed. Our results suggest that late-life neuropsychological test performance can be formally characterized with distributed connectome-based predictive models, and further translational evidence is needed when developing theoretically valid and clinically incremental predictive models.

Neural and social correlates of attitudinal brokerage: using the complete social networks of two entire villages.

To avoid polarization and maintain small-worldness in society, people who act as attitudinal brokers are critical. These people maintain social ties with people who have dissimilar and even incompatible attitudes. Based on resting-state functional magnetic resonance imaging (n = 139) and the complete social networks from two Korean villages (n = 1508), we investigated the individual-level neural capacity and social-level structural opportunity for attitudinal brokerage regarding gender role attitudes. First, using a connectome-based predictive model, we successfully identified the brain functional connectivity that predicts attitudinal diversity of respondents' social network members. Brain regions that contributed most to the prediction included mentalizing regions known to be recruited in reading and understanding others' belief states. This result was corroborated by leave-one-out cross-validation, fivefold cross-validation and external validation where the brain connectivity identified in one village was used to predict the attitudinal diversity in another independent village. Second, the association between functional connectivity and attitudinal diversity of social network members was contingent on a specific position in a social network, namely, the structural brokerage position where people have ties with two people who are not otherwise connected.

Computed Tomography-Derived Skeletal Muscle Radiodensity Predicts Peak Weight-Corrected Jump Power in Older Adults: The Korean Urban Rural Elderly (KURE) Study.

Computed tomography (CT)-derived skeletal muscle area (SMA) and skeletal muscle radiodensity (SMD) reflect distinctive quantitative and qualitative characteristics of skeletal muscles. However, data on whether CT-based muscle parameters, especially SMD, can predict muscle function is limited. In a prospective cohort, 1523 community-dwelling older adults who underwent abdominal CT scans and the countermovement two-legged jumping test on a ground reaction force platform were analyzed (mean age 74.7 years, 65.1% women). SMA and SMD were measured at third lumbar vertebra level (L3). Individuals with low jump power (peak weight-corrected jump power < 23.8 W/kg in men and < 19.0 W/kg in women using clinically validated threshold) were older; had lower SMA, SMD, and maximal grip strength values; and had lower chair rise test and timed up and go test performance than those without low jump power. SMD was positively associated with peak weight-corrected jump power (adjusted ß = 0.33 and 0.23 per 1 HU increase in men and women, respectively, p < 0.001). One HU decrement in SMD was associated with 10% elevated odds of low jump power (adjusted OR [aOR] 1.10, p < 0.001) after adjusting for age, sex, height, inflammation, and insulin resistance markers, whereas the association of SMA with low jump power was attenuated (aOR 1.00, p = 0.721). SMD showed better discrimination for low jump power than SMA (AUC 0.699 vs. 0.617, p < 0.001), with additional improvement when added to SMA and conventional risk factors (AUC 0.745 to 0.773, p < 0.001). Therefore, CT-measured L3 SMD can be a sensitive surrogate marker for muscle function along with SMA in older adults, which merits further investigation.

Gender differences in the longitudinal association between husbands' and wives' depressive symptoms among Korean older adults: the moderating effects of the spousal relationship.

PURPOSE: The mutual effects of depressive symptoms between couples have long been reported; however, it remains unknown whether the spousal concordance in depressive symptoms differs depending on spousal relationships. METHOD: Data on 291 married couples from the Korean Social Life, Health, and Aging Project (KSHAP) were examined. The KSHAP collected global network data from the target population living in one Korean village over eight years and across five waves. A seemingly unrelated regression (SUR) model in the panel data was employed to address correlations and heterogeneity. RESULTS: If one spouse (husband or wife) had depressive symptoms, the other spouse tended to have depressive symptoms. However, the effect of marital relations on spousal concordance in depressive symptoms was different among husbands and wives. This study demonstrated both spousal support and spousal network aspects of spousal relationships. Depression concordance was stronger for couples with more negative marital relationship. A supportive marital relationship was associated with less concordance between spouses' depressive symptoms for wives but not for husbands. Spousal network overlap was associated with less depression concordance for husbands; however, for wives, spousal network overlap was directly associated with more depressive symptoms and did not mediate the association with depression concordance. CONCLUSION: Our findings suggest that approaches to supporting older adults dealing with mental health disorders may involve support at both the individual and couple levels. Gender-specific strategies could also be devised to improve the mental well-being of the older population.

Exploring the contingent associations between functional limitations and depressive symptoms across residential context: a multilevel panel data analysis.

Objectives: This study examines the multilevel relationship between functional limitations and depressive symptoms among community-dwelling US older adults, and how it is moderated by community environmental characteristics (neighborhood fear, social cohesion, structural disadvantage and residential stability).Method: Data come from two waves of National Social Life, Health and Aging Project (NSHAP) collected in 2005/2006 and 2010/2011, consisting of 2,261 individuals aged 57-85 (mean = 68.5; SD = 7.5) nested in 100 regional areas. Two-level hierarchical linear models are fitted to test if and to what extent limited physical capacity and neighborhood measures are interactively related to depressive symptoms.Results: Adjusting for confounders (e.g. age, gender, education, employment status, social support), we find a significant positive relationship between functional limitations and depressive symptoms. At the aggregate level, socially cohesive neighborhoods are negatively related to depression. Several cross-level interactions are also observed. First, the association between poor functional health and depression is greater in neighborhoods perceived to be less safe. It is also stronger in places with more structural disadvantages. Lastly, the physical impairment-depression link is more pronounced where there is higher residential stability, i.e., greater proportion of long-term residents.Conclusion: Our study bridges an important empirical gap in the literature. Prior studies have rarely investigated how the connection between functional limitations and depressive symptoms among older adults is conditioned by neighborhood characteristics. By using multilevel analysis of population-based longitudinal data, we show that physical space (neighborhood community) plays a critical role in understanding this important, yet understudied, relationship.

Elevated Red Blood Cell Distribution Width Is Associated with Morphometric Vertebral Fracture in Community-Dwelling Older Adults, Independent of Anemia, Inflammation, and Nutritional Status: The Korean Urban Rural Elderly (KURE) Study.

Elevated red blood cell distribution width (RDW), a simple measure of red blood cell size heterogeneity, has been associated with increased mortality and morbidity in the elderly population, which might reflect systemic inflammation and malnutrition. However, whether elevated RDW is associated with prevalent morphometric vertebral fracture (VF) in older adults has not been investigated. We examined 2127 individuals (mean age 71.7 years; women 66%) from a community-based cohort. VF was defined as ≥ 25% reduction in vertebral column height using the Genant semiquantitative method. Multiple VF was defined as the presence of VF at two or more sites. The prevalence of any VF and multiple VF was 14% and 4%, respectively, increasing from the lowest to the highest RDW tertiles (12-18% and 3-6%, p for trend < 0.05 for all). RDW was positively associated with age, body mass index (BMI), malnutrition, and high-sensitivity C-reactive protein (hsCRP), whereas it was negatively associated with albumin, hemoglobin, and ferritin levels. Elevated RDW was associated with any VF [adjusted odds ratio (aOR) 1.26; p = 0.008] and multiple VF (aOR 1.36; p = 0.010) after adjustment for covariates, including age, sex, BMI, hsCRP, malnutrition, self-reported previous fracture, falls, osteoporosis, and hemoglobin and ferritin levels. The association between elevated RDW and VF remained robust in subgroups with (aOR 1.39; p = 0.048) or without anemia (aOR 1.26; p = 0.030). Elevated RDW was associated with prevalent morphometric VF in community-dwelling elderly individuals, independent of anemia, inflammation, and nutritional status.

Associations of systemic inflammation with frontotemporal functional network connectivity and out-degree social-network size in community-dwelling older adults.

Increasing evidence suggests that systemic inflammation adversely affects social experiences and behaviors of older adults by changing the functional state of the brain. In this study, we investigated the relationships among systemic inflammation, functional network connectivity (FNC) of the whole brain, and social-network size using complete social-network data of older adults residing in a Korean village. Sixty-one participants were recruited from the Korean Social Life, Health, and Aging Project (KSHAP). Participants underwent a resting-state functional magnetic resonance imaging scan. High sensitivity C-reactive protein (hs-CRP) levels were measured as an inflammation marker. In-degree and out-degree network sizes were calculated based on the total number of intimate social relationships per participant. We demonstrated that hs-CRP levels were associated with decreased frontotemporal FNC. Stronger frontotemporal FNC was significantly correlated with a larger out-degree network size, suggesting that impaired frontotemporal communication in older adults decreases perceived social connectedness with other people. An exploratory mediation analysis supported the observation that increased systemic inflammation contributes to reduced out-degree social-network size among older adults by changing frontotemporal FNC. The present findings provide meaningful insight into the complex relationship between systemic inflammation and social quality of life.

Association between estimated glomerular filtration rate (eGFR) and asymmetric dimethylarginine (ADMA) concentrations among the elderly in a rural community: a cross-sectional study.

BACKGROUND: Reduced glomerular filtration rate and increased asymmetric dimethylarginine (ADMA) are prevalent in elderly people. However, most of the studies that have examined the association between the two conditions were performed in patients with renal dysfunction, but not in the general elderly population. Thus, we investigated an association between estimated glomerular filtration rate (eGFR) and ADMA concentration among community-dwelling older Koreans. METHODS: A cross-sectional study was conducted on 269 men and 382 women (mean age, 71.6 years) enrolled in the Korean Social Life, Health, and Aging Project (KSHAP), a population-based cohort study of health determinants in elderly Koreans. We calculated eGFR using chronic kidney disease- Epidemiology Collaboration Group (CKD-EPI) equation. ADMA concentration was measured by an enzyme-linked immunosorbent assay. The association between eGFR and ADMA concentrations was analyzed by multiple linear regression models. RESULTS: The mean ADMA was significantly higher in people with eGFR< 60 mL/min/1.73m2 (0.691 µmol/L) than in those with eGFR≥60 mL/min/1.73m2 (0.667 µmol/L, p = 0.013). The negative correlations between eGFR level and ADMA concentrations were significant in men and women after adjusted age. After adjusting for potential confounders which were sex, age, body surface, blood pressure, total and HDL cholesterol, diabetes, smoking, and drinking, eGFR levels were inversely associated with ADMA concentrations both in men (ß = - 0.0015, p = 0.005) and women (ß = - 0.001, p = 0.039). CONCLUSION: Our findings suggest that an inverse association exists between eGFR and ADMA concentrations among the Korean elderly in a rural community.

Associations of serum 25-hydroxyvitamin D with metabolic syndrome and its components in elderly men and women: the Korean Urban Rural Elderly cohort study.

BACKGROUND: Many studies have investigated the association between vitamin D and metabolic syndrome (MetS). However, few studies have investigated the association stratified by sex in the elderly. Therefore, we aimed to evaluate the association between vitamin D, MetS, and its components in Korean elderly men and women. METHODS: A total of 987 men and 1949 women aged ≥65 years were recruited through Korean Urban Rural Elderly cohort study. Serum 25-hydroxyvitamin D (25(OH)D) levels were categorized into 4 quartiles and all data were analyzed separately by sex. MetS was defined by the revised criteria of the National Cholesterol Education Program Adult Treatment Panel III. RESULTS: The participants in the lowest quartile of serum 25(OH)D showed a significant increase in the prevalence of high waist circumference, elevated triglyceride level, and low high-density lipoprotein cholesterol level, as well as MetS itself, in both men and women in a univariate analysis. After adjusting for potential confounders including age, smoking status, drinking status, exercise status, region of residence, seasonality, and parathyroid hormone level, the lowest 25(OH)D quartile group was associated with a higher risk of MetS (odds ratio [OR] 2.25, 95% confidence interval [CI] 1.48-3.43 in men and OR 1.65, 95% CI 1.27-2.16 in women) compared to the highest 25(OH)D quartile group as the reference group. However, no significant association was found between serum 25(OH)D levels and the prevalence of MetS components including hyperglycemia or hypertension in both men and women. CONCLUSIONS: Low 25(OH)D levels were associated with increased odds of MetS; in particular, they were associated with MetS components of high waist circumference, hypertriglyceridemia, and low high-density lipoprotein-cholesterol, after adjusting for age, smoking, alcohol, exercise, region of residency, and seasonality, in men and women over 65 years old.

Correction to: Associations of serum 25-hydroxyvitamin D with metabolic syndrome and its components in elderly men and women: the Korean Urban Rural Elderly cohort study.

Following the publication of this article [1], the authors reported an error in one of the author's names. In this Correction the incorrect and correct author name are shown. The original publication of this article has been corrected.

Social brain volume is associated with in-degree social network size among older adults.

The social brain hypothesis proposes that large neocortex size evolved to support cognitively demanding social interactions. Accordingly, previous studies have observed that larger orbitofrontal and amygdala structures predict the size of an individual's social network. However, it remains uncertain how an individual's social connectedness reported by other people is associated with the social brain volume. In this study, we found that a greater in-degree network size, a measure of social ties identified by a subject's social connections rather than by the subject, significantly correlated with a larger regional volume of the orbitofrontal cortex, dorsomedial prefrontal cortex and lingual gyrus. By contrast, out-degree size, which is based on an individual's self-perceived connectedness, showed no associations. Meta-analytic reverse inference further revealed that regional volume pattern of in-degree size was specifically involved in social inference ability. These findings were possible because our dataset contained the social networks of an entire village, i.e. a global network. The results suggest that the in-degree aspect of social network size not only confirms the previously reported brain correlates of the social network but also shows an association in brain regions involved in the ability to infer other people's minds. This study provides insight into understanding how the social brain is uniquely associated with sociocentric measures derived from a global network.

Low peak jump power is associated with elevated odds of dysmobility syndrome in community-dwelling elderly individuals: the Korean Urban Rural Elderly (KURE) study.

In a community-dwelling elderly cohort (Korean Urban Rural Elderly), low peak jump power was associated with elevated odds of dysmobility syndrome and its components, independent of age and comorbidities. Jump power measurement improved discrimination of individuals with dysmobility syndrome when added to conventional risk factors. INTRODUCTION: Dysmobility syndrome was proposed to encompass the risks affecting musculoskeletal outcomes. Jump power measurement is a safe, reproducible high-intensity test for physical function in elderly. However, the relationship between jump power and dysmobility syndrome remains unknown. METHODS: A total of 1369 subjects (mean 71.6 years; women, 66%) were analyzed from a community-based cohort. Dysmobility syndrome was defined as the presence of ≥ 3 factors among falls in the preceding year, low lean mass, high fat mass, osteoporosis, low grip strength, and low timed get-up-and-go (TUG) performance. Subjects were grouped into tertiles of jump power relative to weight based on sex-stratified cutoffs (32.4 and 27.6 W/kg in men; 23.9 and 19.9 W/kg in women) or into the failed-to-jump group. RESULTS: The prevalence of dysmobility syndrome was 20% overall, increasing from the highest (T1) to lowest (T3) jump power tertile (1, 11, 15% in men; 11, 16, 39% in women) and the failed-to-jump group (39% in men; 48% in women). Low jump power or failed-to-jump was associated with elevated odds of dysmobility syndrome (T3 vs. T1, adjusted odds ratio [aOR] 4.35, p < 0.001; failed-to-jump vs. T1, aOR 7.60, p < 0.001) and its components including falls, low lean mass, high fat mass, and poor TUG performance but not osteoporosis after adjustment for covariates. Jump power modestly discriminated dysmobility syndrome (area under the curve [AUC], 0.71, p < 0.001), which improved discriminatory performance when added to conventional risk factors (AUC, from 0.75 to 0.79, p < 0.001). CONCLUSIONS: Low peak jump power was associated with elevated odds of dysmobility syndrome and its components, independent of age and comorbidities.

Lower Jump Power Rather Than Muscle Mass Itself is Associated with Vertebral Fracture in Community-Dwelling Elderly Korean Women.

Sarcopenia is considered to be a risk factor for osteoporotic fracture, which is a major health problem in elderly women. In this study, we aimed to investigate the association of sarcopenia, with regard to muscle mass and function, with prevalent vertebral fracture in community-dwelling elderly women. We recruited 1281 women aged 64 to 87 years from the Korean Urban Rural Elderly cohort study. Muscle mass and function were measured using bioimpedance analysis and jumping mechanography. Skeletal muscle index (SMI) and jump power were used as an indicator of muscle mass and function, respectively. Among the participants, we observed 282 (18.9%) vertebral fractures and 564 (44.0%) osteoporosis. Although age, body mass index, and prevalence of osteoporosis increased as both SMI and jump power decreased, prevalence of vertebral fracture increased only when jump power decreased. In univariate analysis, compared with the highest quartile of jump power, the lowest quartile had a significant odds ratio of 2.80 (95% CI 1.79-4.36) for vertebral fracture. This association between jump power and vertebral fracture remained significant, with an odds ratio of 3.04 (95% CI 1.77-5.23), even after adjusting for other risk factors including age, bone mineral density, previous fracture, and cognitive function. In contrast, there was no association between SMI and vertebral fracture. Based on our results, low jump power, but not SMI, is associated with vertebral fracture in community-dwelling elderly Korean women. This finding suggests that jump power may have a more important role than muscle mass itself for osteoporotic fracture.

Community Sexual Bridging Among Heterosexuals at High-Risk of HIV in New York City.

Community sexual bridging may influence the socio-geographic distribution of heterosexually transmitted HIV. In a cross-sectional study, heterosexual adults at high-risk of HIV were recruited in New York City (NYC) in 2010 for the Centers for Disease Control and Prevention-sponsored National HIV Behavioral Surveillance system. Eligible participants were interviewed about their HIV risk behaviors and sexual partnerships and tested for HIV. Social network analysis of the geographic location of participants' recent sexual partnerships was used to calculate three sexual bridging measures (non-redundant ties, flow-betweenness and walk-betweenness) for NYC communities (defined as United Hospital Fund neighborhoods), which were plotted against HIV prevalence in each community. The analysis sample comprised 494 participants and 1534 sexual partnerships. Participants were 60.1 % male, 79.6 % non-Hispanic black and 19.6 % Hispanic race/ethnicity; the median age was 40 years (IQR 24-50); 37.7 % had ever been homeless (past 12 months); 16.6 % had ever injected drugs; in the past 12 months 76.7 % used non-injection drugs and 90.1 % engaged in condomless vaginal or anal sex; 9.6 % tested HIV positive (of 481 with positive/negative results). Sexual partnerships were located in 33 (78.6 %) of 42 NYC communities, including 13 "high HIV-spread communities", 7 "hidden bridging communities", 0 "contained high HIV prevalence communities", and 13 "latent HIV bridging communities". Compared with latent HIV bridging communities, the population racial/ethnic composition was more likely (p < 0.0001) to be black or Hispanic in high HIV-spread communities and to be black in hidden bridging communities. High HIV-spread and hidden bridging communities may facilitate the maintenance and spread of heterosexually transmitted HIV in black and Hispanic populations in NYC.

The Korean urban rural elderly cohort study: study design and protocol.

BACKGROUND: Korea is one of the fastest aging countries and is expected to become a super-aged society within 12 years. The Korean Urban Rural Elderly (KURE) study was developed to evaluate the epidemiological characteristics and establish the prevention and management of major disorders of the elderly in Korea. METHODS/DESIGN: The KURE study is a community-based prospective cohort study on health, aging, and common geriatric disorders of Korean elderly persons aged at least 65 years. To construct a cohort reflecting both urban and rural areas, we selected 2 representative communities in the country. To establish multidisciplinary approaches to geriatric health, this study was performed by researchers in the divisions of geriatrics, preventive medicine, endocrinology, and sociology. The baseline examinations began in 2012; the study will follow more than 4,000 elderly Koreans over 10 years. The first and second follow-up health examinations will be performed every 4 years. Every 2 years after each health examination, inter-assessment interview will be conducted to improve participant retention. DISCUSSION: The KURE study will provide longitudinal epidemiologic data on health, aging, and common geriatric disorders of the elderly in Korea. This is a comprehensive, multidisciplinary study of the elderly with respect to biological, physical, socio-economic, and environmental factors. The results of this study will contribute to improve public health and welfare policies for the aging society in Korea.

Social network properties and self-rated health in later life: comparisons from the Korean social life, health, and aging project and the national social life, health and aging project.

BACKGROUND: This paper has two objectives. Firstly, it provides an overview of the social network module, data collection procedures, and measurement of ego-centric and complete-network properties in the Korean Social Life, Health, and Aging Project (KSHAP). Secondly, it directly compares the KSHAP structure and results to the ego-centric network structure and results of the National Social Life, Health, and Aging Project (NSHAP), which conducted in-home interviews with 3,005 persons 57 to 85 years of age in the United States. METHODS: The structure of the complete social network of 814 KSHAP respondents living in Township K was measured and examined at two levels of networks. Ego-centric network properties include network size, composition, volume of contact with network members, density, and bridging potential. Complete-network properties are degree centrality, closeness centrality, betweenness centrality, and brokerage role. RESULTS: We found that KSHAP respondents with a smaller number of social network members were more likely to be older and tended to have poorer self-rated health. Compared to the NSHAP, the KSHAP respondents maintained a smaller network size with a greater network density among their members and lower bridging potential. Further analysis of the complete network properties of KSHAP respondents revealed that more brokerage roles inside the same neighborhood (Ri) were significantly associated with better self-rated health. Socially isolated respondents identified by network components had the worst self-rated health. CONCLUSIONS: The findings demonstrate the importance of social network analysis for the study of older adults' health status in Korea. The study also highlights the importance of complete-network data and its ability to reveal mechanisms beyond ego-centric network data.

The Effect of Cognitive Impairment on the Association Between Social Network Properties and Mortality Among Older Korean Adults.

OBJECTIVES: This study investigated the effect of cognitive impairment on the association between social network properties and mortality among older Korean adults. METHODS: This study used data from the Korean Social Life, Health, and Aging Project. It obtained 814 older adults' complete network maps across an entire village in 2011-2012. Participants' deaths until December 31, 2020 were confirmed by cause-of-death statistics. A Cox proportional hazards model was used to assess the risks of poor social network properties (low degree centrality, perceived loneliness, social non-participation, group-level segregation, and lack of support) on mortality according to cognitive impairment. RESULTS: In total, 675 participants (5510.4 person-years) were analyzed, excluding those with missing data and those whose deaths could not be verified. Along with cognitive impairment, all social network properties except loneliness were independently associated with mortality. When stratified by cognitive function, some variables indicating poor social relations had higher risks among older adults with cognitive impairment, with adjusted hazard ratios (HRs) of 2.12 (95% confidence interval [CI], 1.34 to 3.35) for social nonparticipation, 1.58 (95% CI, 0.94 to 2.65) for group-level segregation, and 3.44 (95% CI, 1.55 to 7.60) for lack of support. On the contrary, these effects were not observed among those with normal cognition, with adjusted HRs of 0.73 (95% CI, 0.31 to 1.71), 0.96 (95% CI, 0.42 to 2.21), and 0.95 (95% CI, 0.23 to 3.96), respectively. CONCLUSIONS: The effect of social network properties was more critical among the elderly with cognitive impairment. Older adults with poor cognitive function are particularly encouraged to participate in social activities to reduce the risk of mortality.