Ageing Well: Studies of its Global and Multidomain and Construct Among Multi-ethnic Singaporean Seniors

Ph.DDOCTOR OF PHILOSOPH

Successful aging, cognitive function, socioeconomic status, and leukocyte telomere length

In a rapidly greying world, the notion that some individuals maintain successful aging trajectories, viz. high physical, cognitive, emotional, and social functioning in older age, is increasingly germane. Biomarkers of such successful aging are increasingly sought. Leukocyte telomere length (LTL), an emerging yardstick of cellular aging that is influenced by but distinct from chronological age, may also be associated to successful aging. Furthermore, given that socio-economic status (SES) influences successful aging trajectories, socioeconomic status may also moderate the association between chronological age and LTL. The goals of this study are to examine 1) whether successful aging is associated with LTL; 2) whether successful aging accounts for age-related LTL and 3) whether low SES moderates the effect of age on LTL. Singaporean Chinese (n = 353) aged 65-80 completed a multidimensional assessment of successful aging and provided blood samples for LTL analysis. Results show that LTL negatively correlates with chronological age and positively correlates with successful aging. Successful aging mediates the association between chronological age and LTL. Moderated mediation analyses show that lower SES is associated with stronger negative associations of chronological age with successful aging and LTL. Moreover, the cognitive functioning dimension of successful aging is uniquely associated with LTL and its association with chronological age is moderated by SES. This study provides evidence that among older Singaporean Chinese with lower SES, declines in successful aging and in cognitive functioning are linked to age-related LTL shortening and hence to accelerated aging at the cellular level

Social connections and risk of incident mild cognitive impairment, dementia, and mortality in 13 longitudinal cohort studies of ageing

INTRODUCTION: Previous meta-analyses have linked social connections and mild cognitive impairment, dementia, and mortality. However, these used aggregate data from North America and Europe and examined a limited number of social connection markers. METHODS: We used individual participant data (N = 39271, Mage  = 70.67 (40-102), 58.86% female, Meducation  = 8.43 years, Mfollow-up  = 3.22 years) from 13 longitudinal ageing studies. A two-stage meta-analysis of Cox regression models examined the association between social connection markers with our primary outcomes. RESULTS: We found associations between good social connections structure and quality and lower risk of incident mild cognitive impairment (MCI); between social structure and function and lower risk of incident dementia and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality. DISCUSSION: Different aspects of social connections - structure, function, and quality - are associated with benefits for healthy aging internationally. HIGHLIGHTS: Social connection structure (being married/in a relationship, weekly community group engagement, weekly family/friend interactions) and quality (never lonely) were associated with lower risk of incident MCI. Social connection structure (monthly/weekly friend/family interactions) and function (having a confidante) were associated with lower risk of incident dementia. Social connection structure (living with others, yearly/monthly/weekly community group engagement) and function (having a confidante) were associated with lower risk of mortality. Evidence from 13 longitudinal cohort studies of ageing indicates that social connections are important targets for reducing risk of incident MCI, incident dementia, and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality

Sex differences in dementia risk and risk factors: Individual‐participant data analysis using 21 cohorts across six continents from the COSMIC consortium

Introduction: Sex differences in dementia risk, and risk factor (RF) associations with dementia, remain uncertain across diverse ethno‐regional groups. Methods: A total of 29,850 participants (58% women) from 21 cohorts across six continents were included in an individual participant data meta‐analysis. Sex‐specific hazard ratios (HRs), and women‐to‐men ratio of hazard ratios (RHRs) for associations between RFs and all‐cause dementia were derived from mixed‐effect Cox models. Results: Incident dementia occurred in 2089 (66% women) participants over 4.6 years (median). Women had higher dementia risk (HR, 1.12 [1.02, 1.23]) than men, particularly in low‐ and lower‐middle‐income economies. Associations between longer education and former alcohol use with dementia risk (RHR, 1.01 [1.00, 1.03] per year, and 0.55 [0.38, 0.79], respectively) were stronger for men than women; otherwise, there were no discernible sex differences in other RFs. Discussion: Dementia risk was higher in women than men, with possible variations by country‐level income settings, but most RFs appear to work similarly in women and men

Global variations in diabetes mellitus based on fasting glucose and haemogloblin A1c

Fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c) are both used to diagnose diabetes, but may identify different people as having diabetes. We used data from 117 population-based studies and quantified, in different world regions, the prevalence of diagnosed diabetes, and whether those who were previously undiagnosed and detected as having diabetes in survey screening had elevated FPG, HbA1c, or both. We developed prediction equations for estimating the probability that a person without previously diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa. The age-standardised proportion of diabetes that was previously undiagnosed, and detected in survey screening, ranged from 30% in the high-income western region to 66% in south Asia. Among those with screen-detected diabetes with either test, the agestandardised proportion who had elevated levels of both FPG and HbA1c was 29-39% across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and middle-income regions, isolated elevated HbA1c more common than isolated elevated FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and underestimate diabetes prevalence. Our prediction equations help allocate finite resources for measuring HbA1c to reduce the global gap in diabetes diagnosis and surveillance.peer-reviewe

Happy people live longer because they are healthy people

Abstract Objectives Higher levels of happiness are associated with longer life expectancy. Our study assessed the extent to which various factors explain the protective effect of happiness on all-cause mortality risk, and whether the association differs between older men and women. Methods Using data from the Singapore Longitudinal Aging Studies (N = 6073) of community-dwelling older adults aged ≥ 55 years, we analyzed the association of baseline Likert score of happiness (1 = very sad to 5 = very happy) and mortality from mean 11.7 years of follow up. Cox regression models were used to assess the extent to which confounding risk factors attenuated the hazard ratio of association in the whole sample and sex-stratified analyses. Results Happiness was significantly associated with lower mortality (p < .001) adjusted for age, sex and ethnicity: HR = 0.85 per integer score and HR = 0.57 for fairly-or-very happy versus fairly-or-very sad. The HR estimate (0.90 per integer score) was modestly attenuated (33.3%) in models that included socio-demographic and support, lifestyle or physical health and functioning factor, but remained statistically significant. The HR estimate (0.94 per integer score) was substantially attenuated (60%) and was insignificant in the model that included psychological health and functioning. Including all co-varying factors in the model resulted in statistically insignificant HR estimate (1.04 per integer score). Similar results were obtained for HR estimates for fairly-to-very happy versus fairly-to- very sad). Discussion Much of the association between happiness and increased life expectancy could be explained by socio-demographic, lifestyle, health and functioning factors, and especially psychological health and functioning factors

Socio-Environmental, Lifestyle, Behavioural, and Psychological Determinants of Biological Ageing: The Singapore Longitudinal Ageing Study

10.1159/000511211Gerontology666603–61

Physical and functional measures predicting long-term mortality in community-dwelling older adults: a comparative evaluation in the Singapore Longitudinal Ageing Study

10.18632/aging.203756Aging132325038-2505

Resilience, stressful life events, and depressive symptomatology among older Chinese adults

Objective: The association between exposure to stressful life events (SLEs) and late-life depression is well-documented. However, the role of resilience as a buffer against the adverse mental health effects of SLEs in late life has not been convincingly demonstrated. In this paper, the moderating effect of resilience in the relationship between SLEs and depressive symptomatology in older Chinese adults is investigated. Method: A population sample of 385 community-dwelling older Chinese adults aged ≥60 years responded to questionnaires on resilience (Connor–Davidson resilience scale), depressive symptomatology (Geriatric Depression Scale, GDS-15) and SLEs. Results: Increased numbers of SLEs (β = 0.343, p < .001) and lower levels of resilience (β = –0.137, p < 0.001) were significantly associated with higher levels of depressive symptomatology. There was a significant interaction of resilience and number of SLEs on depressive symptomatology (p = 0.003). The sense of personal competence and optimism was the principal underlying resilience dimension moderating the relationship for both the young–old (aged 60–69) and the old–old (aged 70 and above). Conclusion: The finding of significant interaction supported the role of resilience in moderating the adverse effect of SLEs in terms of depressive symptoms among older Chinese adults