Epstein-Barr virus antibody titer as a stress biomarker and its association with social capital in rural Fujian communities, China

Can social support buffer the association between loneliness and hypertension? a cross-sectional study in rural China

Objectives

Hypertension has reached epidemic levels in rural China, where loneliness has been a major problem among community dwellers as a consequence of rural-to-urban migration among younger generations. The objective of the study is to investigate the association between loneliness and hypertension, and whether social support can buffer the association (i.e., stress buffering theory), using cross-sectional data from 765 adults (mean age: 59.1 years) in rural Fujian, China.

Methods

Social support was measured as the reciprocal instrumental social support from/to neighbors and the reciprocal emotional support (i.e., the number of close friends that the respondent could turn to for help immediately when they are in trouble). A mixed-effect Poisson regression model with a robust variance estimator was used to investigate the association between loneliness, social support, and hypertension.

Results

Analysis revealed that those who were lonely had a higher prevalence ratio for hypertension (prevalence ratio = 1.12, 95% confidence interval 0.99–1.26) compared to those who reported not being lonely. There was an interaction between social support and loneliness in relation to hypertension. Specifically, contrary to the stress buffering theory, the positive association between loneliness and hypertension was more pronounced among those who reported higher social support compared to those who reported lower support (p for interaction <0.001 for instrumental support).

Conclusion

The results suggest that being lonely despite high levels of social support poses the greatest risk for hypertension. This study did not confirm a buffering effect of social support on the association between loneliness and hypertension.

Stress-Induced Epstein-Barr Virus Reactivation

Epstein-Barr virus (EBV) is typically found in a latent, asymptomatic state in immunocompetent individuals. Perturbations of the host immune system can stimulate viral reactivation. Furthermore, there are a myriad of EBV-associated illnesses including various cancers, post-transplant lymphoproliferative disease, and autoimmune conditions. A thorough understanding of this virus, and the interplay between stress and the immune system, is essential to establish effective treatment. This review will provide a summary of the interaction between both psychological and cellular stressors resulting in EBV reactivation. It will examine mechanisms by which EBV establishes and maintains latency and will conclude with a brief overview of treatments targeting EBV.

Income Inequality, Neighbourhood Social Capital and Subjective Well-Being in China: Exploration of a Moderating Effect

With the continuous global rise in inequality and the growing importance of subjective welfare, the relationship between income inequality and subjective well-being has received increasing attention. This paper focuses on neighbourhood social capital, measured at the individual and community levels, to explore its moderating effect on the association between income inequality and subjective well-being in the context of China, an issue few studies have examined. Using data from the China Labour-force Dynamics Survey and multilevel models, the results show that income inequality measured using three different indicators had a stable and negative association with subjective well-being in China, after controlling for various individual characteristics and aggregate-level factors. Although neighbourhood social capital at the individual level has been proven to promote subjective well-being, a dark side of social capital is also found at the community level. More notably, neighbourhood social capital at the individual level can attenuate the negative impact of income inequality on subjective well-being, especially for vulnerable groups, such as those with low income or low education. How to reasonably guide the community to develop social capital is an important policy implication to attenuate the negative psychological experience of income inequality.

Chronic stress and age-related pattern of blood pressure: A cross-sectional study in rural China

OBJECTIVE

Chronic stress is a risk factor for hypertension in adults. However, there is conflicting evidence for older adults. We hypothesized that age-related arterial stiffening, which leads to a lower blood pressure (especially diastolic blood pressure [DBP]), is more pronounced among older adults with high vs low stress. The objectives of this study were (a) to investigate age-related trends in systolic and DBPs among adults in rural Fujian, China, and (b) to examine differences in age-related blood pressure trends according to levels of stress by using Epstein-Barr virus (EBV) antibody titer as a marker of chronic stress status.

METHODS

We collected cross-sectional data from 764 rural community-dwelling adults in rural Fujian, China (mean age = 59.4). Participants were categorized into high and low stress groups by median split of EBV antibody titer. A least-squares regression analysis was used to investigate the association between age and blood pressures.

RESULTS

We observed an inverted U-shaped association between age and DBP, while there was a linear association between age and systolic blood pressure in the overall sample. When stratified by stress, the inverted U-shaped associations with age (both systolic and DBPs) were seen only among those with high stress; DBP peaked at the age of ~68 years, and the declining trend later in life was more clearly observed among those with high chronic stress.

DISCUSSION

Decrease of DBP was more pronounced among older adults with high vs low chronic stress in rural China.

The role of education in the association between self-rated health and levels of C-reactive protein: a cross-sectional study in rural areas of China

OBJECTIVES

This study aims to examine the association between self-rated health (SRH) and levels of C-reactive protein (CRP) among adults aged 45 to 101 years old in rural areas of China, and to explore the role of education in the association.

DESIGN

Cross-sectional study.

SETTING

The study population was derived from two databases in China: Nanping project (NP) and the China Health and Retirement Longitudinal Study (CHARLS).

PARTICIPANTS

There were 646 participants from a rural area of Nanping (NP) and 8555 rural participants from a national representative sample of China (CHARLS).

METHODS

CRP was measured using a high sensitivity sandwich enzyme immunoassay in the NP and immunoturbidimetric assay in the CHARLS. SRH was assessed by SRH questionnaires and categorised into good and poor. Education was measured by the maximum years of schooling and dichotomised into illiterate and literate. Multivariate linear regression models were used to study the associations.

RESULTS

Compared to people with good SRH, those with poor SRH had higher levels of CRP in NP (β=0.16, 95% CI -0.02 to 0.34) and in CHARLS (β=0.07, 95% CI 0.02 to 0.11) after adjusting for potential confounders. Similar findings were observed in the pooled population (β=0.08, 95% CI 0.03 to 0.12), especially in men (β=0.13, 95% CI 0.06 to 0.20) and in literate people (β=0.12, 95% CI 0.06 to 0.18).

CONCLUSION

Poor SRH may be a predicator of elevated levels of CRP among middle-aged and older people in rural areas, especially in men and literate people.

The association between family members' migration and Epstein-Barr virus antibody titers among people left behind in rural Fujian, China

OBJECTIVES

In contrast to the health of migrants, which has been extensively studied, little attention has been paid to the health of adults left behind by family members who out-migrated to other locations. This study was performed to investigate the association between being left behind and the Epstein-Barr virus (EBV) antibody titer, which is an indicator of cellular immune functioning previously shown to be associated with psychological stress.

METHODS

A cross-sectional survey was conducted in rural communities in Fujian, China, in 2015. Questionnaire data and dried blood spot samples were collected from 748 adults. A mixed effect regression analysis was conducted to investigate the association.

RESULTS

Results indicated that the EBV antibody titers were higher among people who had been left behind compared with those who had not.

CONCLUSIONS

Our findings suggest that, in rural Fujian, China, family separation following the out-migration of family members is an important determinant of psychological stress.

Association between early parental deprivation and cellular immune function among adults in rural Fujian, China

This study investigated the role of childhood parental deprivation in the association between quality of life (QOL) and the Epstein-Barr virus (EBV) antibody titer, a marker of cellular immune functioning, using data from 734 adults living in seven communities in rural Fujian, China. Parental deprivation was defined if either of their parents had died, divorced, or left them for migratory work for more than 1 year before they turned (a) 16 years of age (childhood and adolescence), or (b) 3 years of age (early childhood). A mixed-effects regression analysis with a random effects model revealed that parental deprivation during early childhood was positively associated with the EBV antibody titer (coefficient = 0.33, p = 0.007), whereas parental deprivation during the first 16 years was not. Further analysis incorporating an interaction term between QOL and parental deprivation revealed a significant interaction between QOL and parental deprivation during early childhood; a significant association between QOL and the EBV antibody titer was found only among those who reported parental deprivation during early childhood. This study suggests that parental deprivation during the period of immune system development may be linked with physiological responses to stressors later in life.