Study On The Longitudinal Associations And Mechanisms Between Social Capital And Cognitive Frailty Among Rural Older Adults

Background China is now facing critical challenges of aging population,especially in rural areas.Therefore,promoting healthy aging effectively in rural areas is the top priority of China’s active aging strategy.Increasing studies indicated that cognitive frailty not only directly impact the quality of life,but also significantly increase the risk of adverse health outcomes such as disability,depression,and hospitalization,and thus worsen the quality of life in the elderly as well as impede implementation of healthy aging.However,cognitive frailty was reversible as it was an intermediate condition between age-related diseases and poor prognosis.Currently,the most critical work is to reveal the underlying mechanism of cognitive frailty occurrence in order to put forward targeted interventions and effectively buffer its progression.A small number of studies indicate that social factors are significant determinants of the cognitive frailty occurrence.However,majority of these studies are lack of causal interference prove due to the cross-sectional study design which focus individual analysis and omit the macro social environment effects.Additionally,social capital has also been proved to facilitate healthy ageing as one of the important social determinants.However,there are lack of research on the effect of social capital on cognitive frailty.Therefore,to investigate longitudinal mechanism of cognitive frailty based on social capital theory from individual and community level is an innovative study breakpoint,and the underlying mechanisms will provide operational and strategic evidence to design individual intervention and construct friendly aging community policies.Objectives In this study,we selected the older adults over 60 in rural Shandong Province.Based on the analysis of social capital among rural older adults,we constructed a mechanism model of social capital and cognitive frailty of rural elderly to identify and measure social capital at individual and community level.Additionally,this empirical study analyzed the mechanism of social capital on cognitive frailty from the perspective of direct and indirect aspects and individual and community levels.Finally,we proposed policy suggestions and supporting measures to reduce the occurrence of cognitive frailty among rural older people.Methods In this study,a multi-stage stratified random sampling method was used to conduct a cohort study on 3600 rural elderly people from 3 rural counties,15 towns and 60 villages in Shandong Province.A total of 2785 subjects who participated in baseline and follow-up surveys were included in the study.Factor analysis and individual level clustering were used to measure social capital at individual and community levels respectively.Fried frailty phenotype and Mini-Mental Status Examination were used to measure cognitive frailty,respectively.Basic demographic information,socioeconomic status,life behavior and health status of the respondents were also collected.This paper mainly uses generalized hierarchical linear model(GHLM),lag mixed effect model,longitudinal mediation model and cross-level interaction model to explore the association and mechanism between social capital and cognitive frailty of rural elderly.Main Results In this study area,the incidence of cognitive frailty among older adults living in rural areas of Shandong province is around 7%.The results from a three level GHLM model showed that married status(AOR=0.68,P<0.001),primary education level(AOR=0.53,P<0.001),junior high school education level or above(AOR=0.35,P<0.001),economic status of Quartile 4(AOR=0.55,P<0.001),higher individual social capital(AOR=0.60,P<0.001)were protective factors of cognitive frailty among rural older adults.Moreover,factors such as age(AOR=1.09,P<0.001),lack of physical activity(AOR=1.46,P<0.001),chronic diseases conditions(AOR=1.47,P<0.05),poor physical function(AOR=1.32,P<0.001)and psychological distress(AOR=1.10,P<0.001)were risk factors for cognitive frailty.However,communities with geriatric entertainment centers(AOR=0.52,P<0.001)was regarded as significant protective factor as a background variable.The results of lag mixed effect models showed that the social capital at baseline(T1)has a predictive effect on cognitive frailty at follow-up(AOR=0.53,P<0.001).Based on the GHLM model,the cross-level moderating effects of community social capital is investigated.The results proved that the cross-level interaction term between community social capital and individual social capital was significant at 5%level(OR=0.51,P=0.044).Additionally,the protective effect of individual social capital on cognitive frailty was stronger in communities with high social capital than those with lower social capital.The cross-level interaction between community social capital and individual marital status was also significant at 5%(OR=0.49,P=0.037).Finally,the results of sensitivity analyses showed that high individual social capital had a strong protective effect on cognitive frailty at follow-up after excluding individuals who had cognitive frailty at baseline(OR=0.51,P<0.001).We applied continuous social capital composite score(Z-Score)method and found that higher individual social capital score had a strong protective effect on cognitive frailty at follow-up(OR=0.75,尸<0.001).The longitudinal mediation model with psychological distress as the mediator showed that psychological distress played significant mediating effect between social capital and cognitive frailty(a*b=-0.235,95%CI=-0.432,-0.038,P=0.019),and the mediated effects accounted for 14.27%of the overall effects;also,physical activity and sedentary behavior had statistically significant mediating effect between social capital and cognitive frailty(a*b=0.601,95%CI=-0.946,-0.256,P<0,001),with a proportion of 30.58%.Moreover,Activities of Daily Life(ADL)mediated the relationship between social capital and cognitive frailty,and the mediating effect was statistically significant(a*b=-0.601,95%CI=-0.946,-0.256,P<0.001),accounting for 18.65%of the whole effect.In the mediation pathway of psychological distress,community social capital moderated the relationship between psychological distress and cognitive frailty(OR=0.47,P=0.031).In the mediation pathway of physical activity and sedentary behavior,community center for older adults moderated the relationship between individual social capital and physical activity and sedentary behavior(OR=0.78,P=0.024),and moderated the relationship between physical activity and sedentary behavior and cognitive frailty(OR=0.36,P=0.004).In the mediation pathway of physical function,community center for older adults moderated the relationship between ADL and cognitive frailty(OR=0.35,P=0.007).Conclusions This study reached the following conclusions:(1)The overall incidence of cognitive frailty among rural older adults in Shandong province is relatively high.It indicated that married,higher educational level,higher economic status and higher individual social capital are protective factors of cognitive frailty.At the same time,we realized that age,lack of physical activity,with chronic diseases,poor physical function and psychological distress are risk factors of cognitive frailty.Moreover,community entertainment centers are proved to be a protective factor among rural older adults.However,social capital at the community level did not show a direct protective effect on cognitive frailty.(2)It indicated that higher level of individual’s social capital could reduce the probability of cognitive frailty one year later,and the protective effect is stronger in the group of women,middle school education or higher,and with higher economic status.Additionally,higher level of community social capital can strengthen the protective effect of individual social capital on individual’s cogni tive frailty;and can buffer the effect of unmarried status on individual’s cognitive frailty.(3)The protective effect of individual social capital on cognitive frailty among rural adults was mediated by the pathways of psychological distress,physical activity behavior and physical function.Moreover,the mediating pathway of physical activity behavior accounts for the largest proportion.Finally,community social capital plays a cross-level moderating role in the mediating effect which was mediated by psychological distress.Communities with elderly entertainment centers showed a cross-level mediating role in physical activity and physical function pathways.Policy Suggestions This study proposed the following policy recommendations:①Address the vital effects of social capital in the prevention and intervention of cognitive frailty,and improve social capital of rural elders from individual and community levels;②Deliver targeted strategies to vulnerable groups,such as strengthen the awareness and monitor of cognitive frailty of older adults with low socioeconomic status in rural areas;③Pay attention to the critical results of physical exercise to prevent cognitive frailty,strengthen the promotion and education of physical exercise for the elderly in rural areas;④Improve psychological counseling for rural elders and promote their physical function recovery;⑤Attention should be paid to the effective role of community in preventing and controlling cognitive frailty,and invest more resources and enhance infrastructure in public places by construct entertainment centers for the elders in rural areasStrengths and limitations Strengths:First,in terms of the study design,this is the first study which selected older adults living in rural areas as study group,and explored longitudinal associations and mechanisms of social determinants on cognitive frailty based on cohort data.This study will not only advance adverse health outcome intervention,but also fill the research gaps on cognitive frailty.Moreover,this study will provide new empirical evidence and guidance in the design and implementation of health intervention plans for older adults in rural areas.Second,in terms of the content perspectives,we applied social capital theory in the study of prevention and control of cognitive frailty.At the same time,this study enlarged and deepened research scope by adopting individual and community social capital instead focusing on individual level.Overall,by adopting this vertical and comprehensive study scope,this study has expanded the research scope of cognitive frailty and enriched the study contents in the field of social capital.Third,in terms of the research method,to explored the longitudinal association between social capital and cognitive frailty,we performed the time lag model and using enhanced longitudinal mediation model,which to some extent compensated for the problem of causal inference that cross-sectional data and traditional mediation model could not solve.Limitations:This study only selected Shandong province as the research site,which may affect the interpretation and promotion of the research results.Secondly,the analysis was based on panel data for a short time,and long-term follow-up data were lacking.Therefore,we will conduct research using follow-up data to reveal the long-term effects and mechanisms of social determinants of health on cognitive decline in the elderly,and to investigate the dynamic changes of cognitive decline over time in the future study.