Long-term control of viral replication relies on the efficient differentiation of memory T cells into effector T cells during secondary immune responses. Recent findings have identified T cell precursors for both memory and exhausted T cells, suggesting the existence of progenitor-like effector T cells. These cells can persist without antigenic challenge but expand and acquire effector functions upon recall immune responses.
View Article and Find Full Text PDFFront Psychiatry
November 2024
Background: Adolescence is a pivotal developmental phase, marked by a high prevalence of mental health issues. The Singapore Youth Epidemiology and Resilience (YEAR) study aims to assess the prevalence of mental health symptoms, sociodemographic risk factors, and the protective role of resilience in a multi-ethnic, Asian school-going adolescent population.
Methods: School-based adolescents aged 11-18 and their parents were invited from a stratified sample of national schools, designed to be demographically representative of the mainstream school-going population.
Background: Due to poorer exercise tolerance, it may be challenging for frail older adults to engage in moderate- or vigorous-intensity exercise. While low-intensity exercise interventions may be more feasible, its effectiveness for such population group remains unclear. We examined the effectiveness and implementation of community-based Baduanjin Qigong, a low-intensity exercise program in older adults with varying frailty status.
View Article and Find Full Text PDFNat Commun
September 2024
While rapid demographic changes in Asia are driving the incidence of chronic aging-related diseases, the limited availability of high-quality in vivo data hampers our ability to understand complex multi-factorial contributions, including gut microbial, to healthy aging. Leveraging a well-phenotyped cohort of community-living octogenarians in Singapore, we used deep shotgun-metagenomic sequencing for high-resolution taxonomic and functional characterization of their gut microbiomes (n = 234). Joint species-level analysis with other Asian cohorts identified distinct age-associated shifts characterized by reduction in microbial richness, and specific Alistipes and Bacteroides species enrichment (e.
View Article and Find Full Text PDFInfection by pathogenic microbes is widely hypothesized to be a risk factor for the development of neurocognitive disorders and dementia, but evidence remains limited. We analyzed the association of seropositivity to 11 common pathogens and cumulative infection burden with neurocognitive disorder (mild cognitive impairment and dementia) in a population-based cohort of 475 older individuals (mean age = 67.6 y) followed up over 3-5 years for the risk of MCI-dementia.
View Article and Find Full Text PDFIntroduction: The LIfestyle for BRAin Health (LIBRA) index yields a dementia risk score based on modifiable lifestyle factors and is validated in Western samples. We investigated whether the association between LIBRA scores and incident dementia is moderated by geographical location or sociodemographic characteristics.
Methods: We combined data from 21 prospective cohorts across six continents (N = 31,680) and conducted cohort-specific Cox proportional hazard regression analyses in a two-step individual participant data meta-analysis.
Alzheimers Dement (Amst)
March 2024
Introduction: White matter hyperintensities (WMHs) are an important imaging marker for cerebral small vessel diseases, but their risk factors and cognitive associations have not been well documented in populations of different ethnicities and/or from different geographical regions.
Methods: We investigated how WMHs were associated with vascular risk factors and cognition in both Whites and Asians, using data from five population-based cohorts of non-demented older individuals from Australia, Singapore, South Korea, and Sweden ( = 1946). WMH volumes (whole brain, periventricular, and deep) were quantified with UBO Detector and harmonized using the ComBat model.
J Diabetes Complications
February 2024
Aim: Skeletal muscle mass to visceral fat area ratio (SVR) has been recognised as an index of sarcopenic obesity. SVR is associated with type 2 diabetes mellitus (T2DM), metabolic syndrome and arterial stiffness which are known risk factors for cognitive dysfunction. We aimed to investigate association between SVR and cognitive function in patients with T2DM.
View Article and Find Full Text PDFImportance: The utility of antihypertensives and ideal blood pressure (BP) for dementia prevention in late life remains unclear and highly contested.
Objectives: To assess the associations of hypertension history, antihypertensive use, and baseline measured BP in late life (age >60 years) with dementia and the moderating factors of age, sex, and racial group.
Data Source And Study Selection: Longitudinal, population-based studies of aging participating in the Cohort Studies of Memory in an International Consortium (COSMIC) group were included.
medRxiv
August 2023
Introduction: White matter hyperintensities (WMH) are an important imaging marker for cerebral small vessel diseases, but their risk factors and cognitive associations have not been well-documented in populations of different ethnicities and/or from different geographical regions.
Method: Magnetic resonance imaging data of five population-based cohorts of non-demented older individuals from Australia, Singapore, South Korea, and Sweden (N = 1,946) were examined for WMH and their associations with vascular risk factors and cognition.
Result: Factors associated with larger whole brain WMH volumes included diabetes, hypertension, stroke, current smoking, body mass index, higher alcohol intake and insufficient physical activity.
Introduction: Healthy ageing (HA) indices typically use full questionnaire, performance- or blood-based assessment of functional ability which are time-consuming and resource-intensive. We developed and validated a simple and brief Healthy Ageing Questionnaire (HAQ) index with comparable measurement accuracy.
Methods: The 15-item HAQ (scored 0-100) was developed using data of 500 participants in the Singapore Study of Successful Ageing (SSOSA), a sub-cohort of the Singapore Longitudinal Ageing Study (SLAS-2).
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.
The therapeutic potential of curcumin for many diseases are intensively investigated. However, real-world observational data documenting health and longevity effects associated with dietary curcumin in turmeric from consuming curry in food is lacking. A prospective cohort study of 4551 adults aged 55 + assessed curry consumption (never or < once/year, ≥ once/year to < once/month, ≥ once/month to < once/week, ≥ once/week to < daily, ≥ once daily), prevalent health conditions, blood biomarker indexes of atherogenicity, insulin resistance, and inflammation at baseline, and mean (SD) 11.
View Article and Find Full Text PDFIntroduction: Cognitive frailty is associated with higher risk of dementia and adverse health outcomes. However, multidimensional factors that influence cognitive frailty transitions are not known. We aimed to investigate risk factors of incident cognitive frailty.
View Article and Find Full Text PDFAlzheimers Dement
November 2023
Background: Few studies have compared gait speed and its correlates among different ethnogeographic regions. The goals of this study were to describe usual and rapid gait speed, and identify their correlates across Australian, Asian, and African countries.
Methods: We used data from 6 population-based cohorts of adults aged 65+ from 6 countries and 3 continents (N = 6 472), with samples ranging from 231 to 1 913.
Objective: Appropriate speech-in noise assessment is challenging in multilingual populations. This study aimed to assess whether first preferred language affected performance on an English Digits-in-noise (DIN) test in the local Asian multilingual population, controlling for hearing threshold, age, sex, English fluency and educational status. A secondary aim was to determine the association between DIN test scores and hearing thresholds.
View Article and Find Full Text PDFAlzheimers Dement
August 2023
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.
Introduction: The detection of systemic risk factors aids in the formulation of strategies to prevent multimorbidity and its associated mortality impact. We aimed to determine the associations of inflammatory, metabolic, malnutrition, and frailty indexes with multimorbidity onset and progression and their predictions of multimorbidity-associated mortality risk.
Methods: A prospective cohort study (Singapore Longitudinal Aging Study [SLAS]) of 5,089 community-dwelling older adults aged ≥55 years in two waves of recruitment (SLAS-1: March 2005-September 2007, SLAS-2: January 2013-August 2018).
Background: Housework may provide a sustainable form of physical activity for older adults and improve health and survival outcomes. Longitudinal studies on associations between housework status over time and health outcomes are lacking. We aim to assess the longitudinal association of intensity and duration of housework with frailty and mortality outcomes.
View Article and Find Full Text PDFBackground: Sarcopenia is common among older individuals with and without type 2 diabetes mellitus (T2DM). There are conflicting evidence in support of the role of insulin in the development of age-related and T2DM-related sarcopenia. We investigated the relationships between the levels of fasting insulin and other blood biomarkers related to insulin or lipid metabolism with the presence of sarcopenia in two independent studies.
View Article and Find Full Text PDFIntroduction: Gait variability is associated with frailty, dementia, and falls. Studies on the association of physiological and cognitive factors with gait variability have seldom included middle-aged adults, even though these adults already experienced loss of muscular strength and postural stability. This study aimed a) to examine and compare the trend of gait variability in men and women, across the adult age spectrum, and b) to identify and compare the contributions of physiological and cognitive factors to gait variability.
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