Objectives: Social participation and the psychological well-being of the older adult are correlated. A substantial body of research has delineated the relationship between social participation and the mental health of older adults, while the indicators for assessing the mental health of the older adult are not sufficiently systematic or comprehensive. This study aims to further explore the relationship between social participation and the mental health of older adults from the perspective of mental frailty, providing a reference for the improvement of health among the older adult population.Methods: We selected 9,208 older adults aged 60 years and older from the China Health and Retirement Longitudinal Study (CHARLS) 2013–2018 database. The mental frailty index was constructed, which integrates both depression and cognitive status to assess the mental health status of the older adult. By using a fixed-effects model, we analyzed the impact of social participation on the mental health of the older adult and compared gender, residence and marriage difference. Meanwhile, the instrumental variables method was used to conduct endogeneity tests.Results: Overall, 65.8% of the respondents had low social participation. Social participation had a significant enhancement effect on mental health in the older adult (β = −0.013, p < 0.001). In specific types of social participation, cultural and sports activities (β = −0.006, p < 0.001), communication and educational activities (β = −0.002, p < 0.05), and skill-enhancing (β = −0.006, p < 0.001) activities were negatively correlated with the index of mental frailty of the older adult, whereas volunteering activities (β = 0.002, p < 0.05) was positively correlated with the index of mental frailty of the older adult.Conclusion: Social participation has a positive effect on the mental health of the older adult in China, and the effect varies for the older adult with different characteristics, which suggests that social participation may be a protective factor for the mental health of the older adult population. Targeting differentiated population characteristics, individualized policies should be developed for different groups of older persons.

Background: Alzheimer’s disease and other dementias (ADOD) are growing global health challenges. While existing studies primarily focus on dementia prevention and management in individuals aged 65 and older, evidence suggests that cognitive decline and pathological changes begin earlier (≥55 years). This study focuses on this younger group to enable earlier risk identification and preventive interventions. Methods: This study used GBD 2021 data to extract incidence, prevalence, mortality, and DALYs related to ADOD. Trends from 1992 to 2021 were assessed using the Age-Period-Cohort (APC) model. Future burden from 2022 to 2046 was projected with the Nordpred model and validated using the Bayesian Age-Period-Cohort (BAPC) model. Results: From 1992 to 2021, ADOD incidence among individuals aged ≥55 increased by 143.88%. The age-standardized prevalence rate (ASPR) rose from 3,870.6 to 3,975.8 per 100,000. Deaths in 2021 were 1.75 times higher than in 1992. The age-standardized DALY rate was consistently higher in females, while males showed an upward trend (net drift, 0.05). APC analysis revealed the steepest incidence increase in the 60–64 age group, with earlier rises in males. Period effects indicated unfavorable incidence trends in high-middle SDI and middle-SDI regions, and similarly adverse mortality trends in high-middle and low-middle SDI regions. Projections suggest a slight increase in ASIR and ASMR by 2046, with females maintaining higher rates than males. Conclusion: The global burden of ADOD among individuals aged 55 years and above remains substantial, particularly in East Asia and among females. Given regional heterogeneity, this study recommends developing and implementing region-specific interventions for more effective improvements.

Objectives: Internet use and the results of mental health are related. Numbers of studies presented the association between Internet use and depression, and the middle-aged and elderly adults with multimorbidity are of concern. The study aimed to explore the relationship between Internet use and depression in middle-aged and elderly adults with multimorbidity.Methods: We selected 2550 respondents aged 45 years and above with multimorbidity from the China Health and Retirement Longitudinal Study (CHARLS) 2018 database. Logistic regression models were constructed to examine the effects of Internet use on depression, as well as comparing gender differences. Meanwhile, propensity score matching (PSM) was used to test the robustness of the results.Results: Overall, 49.8% of respondents had a risk of developing depression, and 14.9% of the participants used the Internet. Internet use (OR = 0.66, P = 0.002), type of devices (one type: OR = 0.69, P = .011;≥2 types: OR = 0.53, P = 0.03), frequency of Internet use (regularly: OR = 0.67, P = 0.005) were all inversely associated with depression. Significant differences between genders were observed, Internet use was associated with a lower prevalence of depression among men, while the association was not statistically significant among women.Conclusions: There is a significantly negative association between Internet use and depression in the middle-aged and elderly adults with multimorbidity in China, and this relationship varies across different genders. This suggests that Internet use may be a protective factor for depressive symptoms in the older population, offering a guideline for policymakers to develop specific strategies for different genders.

Volunteer activities have been widely acknowledged as a meaningful form of social participation for older adults, contributing to their subjective well-being. However, the psychological and interpersonal mechanisms linking volunteering to life satisfaction remain insufficiently explored. In particular, how social networks and depressive symptoms jointly mediate this relationship in the Chinese context is yet to be clarified. This study investigates the association between older adults’ participation in volunteer activities and their life satisfaction, with a focus on the sequential mediating roles of social networks and depressive symptoms. Data were drawn from the 2020 wave of the Chinese Longitudinal Aging Social Survey (CLASS), involving 9,828 respondents aged 60 and older. Volunteer participation was measured through self-reported engagement in community service activities. Social networks were assessed using the six-item Lubben Social Network Scale (LSNS-6), while depressive symptoms were evaluated by the 10-item Center for Epidemiologic Studies Depression Scale (CES-D). Life satisfaction was measured with a single-item indicator. A serial mediation model was tested using structural equation modeling with bootstrapping procedures (5,000 samples) to estimate indirect effects. Participation in volunteer activities was positively associated with life satisfaction among older adults. The relationship was partially mediated by social networks and depressive symptoms in sequence. Specifically, volunteering predicted stronger social networks (a₁ = 0.121, p < .001), which in turn were associated with lower depressive symptoms (a₃ = − 0.135, p < .001), subsequently enhancing life satisfaction (b₂ = − 0.094, p < .001). The total indirect effect through both mediators was significant (a₁ × a₃ × b₂ = 0.002, 95% CI [0.001, 0.004]). The direct effect remained significant (c′ = 0.095, 95% CI [0.060, 0.130]), indicating a partial mediation pattern. This study reveals that social networks and depressive symptoms jointly mediate the relationship between volunteer participation and life satisfaction among older adults in China. These findings provide empirical support for integrating social and psychological mechanisms into models of active ageing. Promoting volunteer engagement may enhance both social connectedness and mental health, ultimately improving quality of life in later life.

Objective: To explore the relationship between intergenerational care and life satisfaction of older adults, and to analyze the chain mediating effect of children’s emotional support and depression in this relationship, so as to provide scientific reference for improving the quality of life of older adults. Methods: In total, 2970 older adults ≥60 years old from the China Health and Retirement Longitudinal Study (CHARLS) were selected as the study subjects. The process plug-in of SPSS was used, and the chain mediating effect test was carried out following the Bootstrap method. Results: Intergenerational care was positively correlated with children’s emotional support and life satisfaction (r = 0.123, 0.141, p < 0.001) and negatively correlated with depression (r = −0.096, p < 0.001). The mediating effects of children’s emotional support and depression were significant between intergenerational care and life satisfaction, with a mediating effect of 0.023 (95% CI: 0.015–0.033), 0.028 (95% CI: 0.014–0.043), and the chained mediating effect of children’s emotional support-depression was also significant, with a mediating effect of 0.006 (95% CI: 0.004–0.008). The total indirect effect of children’s emotional support and depression between intergenerational care and life satisfaction was 0.057, accounting for 26.03% of the total effect. Conclusions: Intergenerational care not only directly affects life satisfaction of older adults, but also indirectly affects life satisfaction through the independent mediating effect of children’s emotional support and depression, as well as the chain mediating effect of children’s emotional support-depression. It is essential to create a positive and inclusive social environment for the intergenerational care of older adults.

Objective: To examine how algorithmic inducement mechanisms are associated with digital addiction among Chinese adults aged 60 and above. Methods: A cross-sectional survey was conducted among older users of major Chinese digital platforms. After data screening, 367 valid questionnaires were analyzed. Digital addiction was measured using the Mobile Phone Addiction Index (MPAI), while a self-developed 16-item scale assessed four algorithmic inducement dimensions: preferential incentives–profit-seeking psychological induction, interactive incentives–emotional compensation induction, stage goals–feedback effect induction, and customized recommendations–exploratory psychological induction. Multiple linear regressions were performed, controlling for age, living arrangement, and daily smartphone use duration. Results: Digital addiction was widespread, within the sample, with 77.11% of participants scoring in the moderate or higher range. All four algorithmic dimensions were positively associated with digital addiction ( p < 0.01). Interactive incentives showed the strongest association ( β = 0.343), followed by preferential incentives ( β = 0.227); stage goals ( β = 0.160) and customized recommendations ( β = 0.163) were smaller yet significant. The model explained 79.1% of the variance ( R ² = 0.791). Conclusion: Algorithmic inducements—economic, social–emotional, task-feedback, and exploratory mechanisms—are jointly associated with a shift in older adults’ digital use from instrumental participation to immersive dependence. The study introduces an analytical framework, “algorithmic drive–psychological compensation–structural constraint–behavioral reinforcement,” and calls for coordinated algorithm governance and digital literacy initiatives to promote healthy aging in the digital era.