Objectives To identify data availability, gaps, and patterns for population level prevalence of loneliness globally, to summarise prevalence estimates within World Health Organization regions when feasible through meta-analysis, and to examine temporal trends of loneliness in countries where data exist. Design Systematic review and meta-analysis. Data sources Embase, Medline, PsycINFO, and Scopus for peer reviewed literature, and Google Scholar and Open Grey for grey literature, supplemented by backward reference searching (to 1 September 2021) Eligibility criteria for selecting studies Observational studies based on nationally representative samples (n≥292), validated instruments, and prevalence data for 2000-19. Two researchers independently extracted data and assessed the risk of bias using the Joanna Briggs Institute checklist. Random effects meta-analysis was conducted in the subset of studies with relatively homogeneous research methods by measurement instrument, age group, and WHO region. Results Prevalence data were available for 113 countries or territories, according to official WHO nomenclature for regions, from 57 studies. Data were available for adolescents (12-17 years) in 77 countries or territories, young adults (18-29 years) in 30 countries, middle aged adults (30-59 years) in 32 countries, and older adults (≥60 years) in 40 countries. Data for all age groups except adolescents were lacking outside of Europe. Overall, 212 estimates for 106 countries from 24 studies were included in meta-analyses. The pooled prevalence of loneliness for adolescents ranged from 9.2% (95% confidence interval 6.8% to 12.4%) in South-East Asia to 14.4% (12.2% to 17.1%) in the Eastern Mediterranean region. For adults, meta-analysis was conducted for the European region only, and a consistent geographical pattern was shown for all adult age groups. The lowest prevalence of loneliness was consistently observed in northern European countries (2.9%, 1.8% to 4.5% for young adults; 2.7%, 2.4% to 3.0% for middle aged adults; and 5.2%, 4.2% to 6.5% for older adults) and the highest in eastern European countries (7.5%, 5.9% to 9.4% for young adults; 9.6%, 7.7% to 12.0% for middle aged adults; and 21.3%, 18.7% to 24.2% for older adults). Conclusion Problematic levels of loneliness are experienced by a substantial proportion of the population in many countries. The substantial difference in data coverage between high income countries (particularly Europe) and low and middle income countries raised an important equity issue. Evidence on the temporal trends of loneliness is insufficient. The findings of this meta-analysis are limited by data scarcity and methodological heterogeneity. Loneliness should be incorporated into general health surveillance with broader geographical and age coverage, using standardised and validated measurement tools. Systematic review registration PROSPERO CRD42019131448.

Background: Social engagement forms the basis of social relationships by providing a sense of belonging, social identity, and fulfillment. Previous research demonstrates that social engagement was associated with positive health behaviors among older adults. However, the results have been different across health-related behaviors, and mostly based on data from high-income countries. For example, studies from the US and UK showed that social engagement was protective against smoking, while others found social engagement encouraged more smoking in many Asian cultures. In this study, we aim to examine the association between social engagement and a range of health-related behaviors and subjective well-being among older adults in six low- to middle-income countries. Methods: Data from the WHO Study on Global Ageing and Adult Health (SAGE Wave 1) were used. A total of 33,338 individuals aged 50 and older in China, Russia, India, Ghana, South Africa, and Mexico were included. Social engagement, tobacco use, alcohol consumption, fruit and vegetable intake, physical activity, sedentary behavior, sleep duration, depression symptoms, self-rated health status, and quality of life were assessed using established self-reported measures. Multiple logistic regression models were used to examine the relationship between social engagement and nine outcome variables, adjusting for socio-demographic characteristics. Results: Lower levels of social engagement were positively related to physical inactivity, prolonged sitting time, unhealthy sleep duration, perceived depression, poor self-rated health, and low quality of life. However, the associations between social engagement and tobacco use, excessive drinking, and insufficient fruit and vegetable intake were mixed across countries. Conclusion: This international study found high social engagement as a potential health-promoting factor in some low- to middle-income countries. Although the impacts of social engagement on tobacco and alcohol use and diet were complicated and culture-specific, interventions at both individual and community levels should encourage healthy lifestyles through positive social engagement.

Despite the rapid increase in evidence from the past decade on daily steps and health-related outcomes, existing systematic reviews primarily focused on few outcomes, such as all-cause mortality. This study synthesised the prospective dose-response relationship between daily steps and health outcomes including all-cause mortality, cardiovascular disease, cancer, type 2 diabetes, cognitive outcomes, mental health outcomes, physical function, and falls. For this systematic review and meta-analysis, we searched PubMed and EBSCO CINAHL for literature published between Jan 1, 2014, and Feb 14, 2025, supplemented by other search strategies. Eligible prospective studies examined the relationship between device-measured daily steps and health outcomes among adults without restrictions on language or publication type. Pairs of reviewers (BN, KO, ML, and TN) independently did the study selection, data extraction, and risk of bias assessment using the 9-point Newcastle-Ottawa Scale. Hazard ratios (HRs) from individual studies were synthesised using random-effects dose-response meta-analysis where possible. Certainty of evidence was assessed using GRADE. This trial is registered with PROSPERO (CRD42024529706). 57 studies from 35 cohorts were included in the systematic review and 31 studies from 24 cohorts were included in meta-analyses. For all-cause mortality, cardiovascular disease incidence, dementia, and falls, an inverse non-linear dose-response association was found, with inflection points at around 5000-7000 steps per day. An inverse linear association was found for cardiovascular disease mortality, cancer incidence, cancer mortality, type 2 diabetes incidence, and depressive symptoms. Based on our meta-analyses, compared with 2000 steps per day, 7000 steps per day was associated with a 47% lower risk of all-cause mortality (HR 0·53 [95% CI 0·46-0·60]; I²=36·3; 14 studies), a 25% lower risk of cardiovascular disease incidence (HR 0·75 [0·67-0·85]; I²=38·3%; six studies), a 47% lower risk of cardiovascular disease mortality (HR 0·53 [0·37-0·77]; I²=78·2%; three studies), a non-significant 6% lower risk of cancer incidence (HR 0·94 [0·87-1·01]; I²=73·7%; two studies), a 37% lower risk of cancer mortality (HR 0·63 [0·55-0·72]; I²=64·5%; three studies), a 14% lower risk of type 2 diabetes (HR 0·86 [0·74-0·99]; I²=48·5%; four studies), a 38% lower risk of dementia (HR 0·62 [0·53-0·73]; I²=0%; two studies), a 22% lower risk of depressive symptoms (HR 0·78 [0·73-0·83]; I²=36·2%; three studies), and a 28% lower risk of falls (HR 0·72 [0·65-0·81]; I²=47·5%; four studies). Studies on physical function (not based on meta-analysis) reported similar inverse associations. The evidence certainty was moderate for all outcomes except for cardiovascular disease mortality (low), cancer incidence (low), physical function (low), and falls (very low). Although 10 000 steps per day can still be a viable target for those who are more active, 7000 steps per day is associated with clinically meaningful improvements in health outcomes and might be a more realistic and achievable target for some. The findings of the study should be interpreted in light of limitations, such as the small number of studies available for most outcomes, a lack of age-specific analysis and biases at the individual study level, including residual confounding. National Health and Medical Research Council, New South Wales Health, and Ian Potter Foundation.

Objective Although 30 min/day of moderate-intensity physical activity is suggested for preventing type 2 diabetes (T2D), the current recommendations exclusively rely on self-reports and rarely consider the genetic risk. We examined the prospective dose-response relationships between total/intensity-specific physical activity and incident T2D accounting for and stratified by different levels of genetic risk. Methods This prospective cohort study was based on 59 325 participants in the UK Biobank (mean age=61.1 years in 2013–2015). Total/intensity-specific physical activity was collected using accelerometers and linked to national registries until 30 September 2021. We examined the shape of the dose-response association between physical activity and T2D incidence using restricted cubic splines adjusted for and stratified by a polygenic risk score (based on 424 selected single nucleotide polymorphisms) using Cox proportional hazards models. Results During a median follow-up of 6.8 years, there was a strong linear dose-response association between moderate-to-vigorous-intensity physical activity (MVPA) and incident T2D, even after adjusting for genetic risk. Compared with the least active participants, the HRs (95% CI) for higher levels of MVPA were: 0.63 (0.53 to 0.75) for 5.3–25.9 min/day, 0.41 (0.34 to 0.51) for 26.0–68.4 min/day and 0.26 (0.18 to 0.38) for >68.4 min/day. While no significant multiplicative interaction between physical activity measures and genetic risk was found, we found a significant additive interaction between MVPA and genetic risk score, suggesting larger absolute risk differences by MVPA levels among those with higher genetic risk. Conclusion Participation in physical activity, particularly MVPA, should be promoted especially in those with high genetic risk of T2D. There may be no minimal or maximal threshold for the benefits. This finding can inform future guidelines development and interventions to prevent T2D.

Purpose: The purpose of this paper is to investigate how WeChat addiction influences users’ physical, mental, and social health. Design/methodology/approach: A national survey was conducted in China. A total of 1,058 responses were collected from 31 regions of China. Findings: The regression results show that WeChat addiction is negatively associated with users’ physical, mental, and social health. The negative effects are significant even after adjusting for the effects of the Big Five personality traits, years of using WeChat, and demographic variables such as age, gender, education level, and monthly income. Years of using WeChat is not significantly related to users’ health. It is also found that the influence of WeChat addiction on health outcomes is sensitive to years of WeChat use. The influence is dormant when users have less than three years of WeChat usage, but starts to exhibit itself after three years. Research limitations/implications: Addictive use of WeChat is associated with declining overall health among Chinese users. Given the cross-sectional nature of this study, definite causal relationship between WeChat addiction and health deterioration cannot be established. Controlled experiments are needed to further examine the causal effects of WeChat addiction. Originality/value: WeChat is the most popular mobile social network service (SNS) in China, but its comprehensive impact on users’ health is rarely studied. This paper extends the extant research on SNS addiction by providing a deepened understanding of how mobile SNS addiction affects personal health in the unique context of WeChat, which provides an important contribution to the interdisciplinary research in public health, psychology, and information systems.

Previous research suggests that while leisure-time physical activity (LTPA) is beneficial, occupational physical activity (OPA) may be detrimental to health, known as the ‘physical activity paradox’. However, the current evidence is primarily based on data from Western countries. We examined the association of OPA with all-cause and cardiovascular disease mortality in working adults in urban China. This prospective longitudinal study was based on a sample of 142,302 urban working adults aged 30–79 years from the China Kadoorie Biobank study. Self-reported OPA (mainly sedentary, standing occupation, and manual work) was collected at baseline (year 2004–2008) and linked to death registries until 31st December 2016. Multivariable Cox proportional hazards models were used to examine the relationship between OPA and mortality outcomes, with further tests for effect modification by sex, educational attainment and LTPA. During a median follow-up of 10·2 years, 4,077 deaths occurred, of which cardiovascular disease was the primary cause for 727 deaths. Crude modelling showed that compared with the sedentary workers, manual work was associated with increased risk of all-cause mortality. However, after adjusting for socio-demographic and lifestyle variables, the association was attenuated to null (HR=1·00, 95%CI: 0·93–1·08). In subgroup analysis, higher OPA was associated with lower risk of all-cause mortality in the least educated group (HR=0·84, 95%CI: 0·75–0·95 for manual work, and HR=0·86, 95%CI: 0·75–0·99 for standing occupation), but harmful in the most educated group (HR=1·17, 95%CI: 1·01–1·36) and in those who reported regular LTPA (HR=1·20, 95%CI: 1·01–1·43). OPA was not associated with mortality risk in the overall sample. However, findings support the ‘physical activity paradox’ within better educated Chinese workers. None.