The longitudinal relation between social reserve and smaller subsequent decline in executive functioning in old age is mediated via cognitive reserve

Longitudinal validation of cognitive reserve proxy measures: a cohort study in a rural Chinese community

BACKGROUND

While evidence supports cognitive reserve (CR) in preserving cognitive function, longitudinal validation of CR proxies, including later-life factors, remains scarce. This study aims to validate CR's stability over time and its relation to cognitive function in rural Chinese older adults.

METHODS

Within the project on the health status of rural older adults (HSRO), the survey included baseline assessment (2019) and follow-up assessment (2022). 792 older adults (mean age: 70.23 years) were followed up. The confirmatory factor analysis (CFA) was constructed using cognitive reserve proxies that included years of formal education, social support, hobbies, and exercise. We examined the longitudinal validity of the CR factor using confirmatory factor analyses and measurement invariance and explored the association of CR with cognition using Spearman's correlation and Generalized Estimating Equations (GEE).

RESULTS

The results showed that CR's CFA structure was stable over time (T0, χ2/df: 3.21/2; RMSEA: 0.02, and T1, χ2/df: 7.47/2; RMSEA: 0.05) and that it accepted both configural and metric invariance (Δχ2/df = 2.28/3, P = 0.52). In addition, it was found that CR had a stable positive relationship with cognitive function across time (T0, r = 0.54; T1, r = 0.49). Furthermore, longitudinal CR were associated with MMSE (β = 2.25; 95%CI = 2.01 ~ 2.49).

CONCLUSIONS

This study provided valuable evidence on the stability and validity of cognitive reserve proxy measures in rural Chinese older adults. Our findings suggested that cognitive reserve is associated with cognitive function over time and highlighted the importance of accumulating cognitive reserve in later life.

The Current and Retrospective Cognitive Reserve (2CR) survey and its relationship with cognitive and mood measures

Cognitive Reserve (CR) is often assessed with surveys spanning demographic, lifestyle, and socio-behavioral variables. The role of both past and current life experiences on CR has, however, rarely been examined. We developed the Current and Retrospective Cognitive Reserve (2CR) survey to assess classical CR proxies (socio-economic status, engagement in leisure and social activities) and other dimensions of potential importance (family engagement, religious/spiritual activity) both currently (CRc; in later adulthood) and retrospectively (CRr; as recalled from younger adulthood). We administered the 2CR, measures of general cognitive functioning, working memory (WM), crystallized-vocabulary- and fluid-reasoning-intelligence, and depressive symptoms (DS) to 235 community-dwelling Italian adults (ages 55-90 years). We used exploratory and confirmatory factor analyses to examine the 2CR latent structure, and we estimated correlations of its dimensions with cognitive abilities and DS. Analyses confirmed a three-level factor structure with two global CR factors (CRc and CRr) at the top level, dimensional CR factors (socio-economic status, family engagement, leisure activity, social engagement, and religious/spiritual activity) at mid-level and observed items at the lowest level. Item-factor representations partially differed across CRc and CRr. Both CRc and CRr were positively correlated with measures of intelligence, WM and DS, but associations of measures of intelligence were stronger for CRr, whereas associations of WM and DS were slightly stronger for CRc. The 2CR can be considered a reliable survey for assessing CR proxies within a multidimensional, "life stage-dependent" framework insofar as CRc are CRr closely related but also differently associated with intelligence, WM, and DS.

Assessing the role of depressive symptoms in the association between social engagement and cognitive functioning among older adults: analysis of cross-sectional data from the Longitudinal Aging Study in India (LASI)

OBJECTIVE

The present study aimed to examine the confounding effects of depressive symptoms and the role of gender in the association between social engagement and cognitive functioning among older Indian adults.

DESIGN

Large-scale cross-sectional survey data were analysed.

SETTING AND PARTICIPANTS

Data from the Longitudinal Aging Study in India (2017-2019) were used in the analysis. The sample included 23 584 individuals aged 60 years and above (11 403 men and 12 181 women).

OUTCOME MEASURES

The outcome variable was cognitive functioning, which was based on various measures including immediate and delayed word recall, orientation, executive functioning, arithmetic ability and object naming. Social engagement measure consists of marital status, living arrangement, availability of confidant, and participation in indoor games, and social and cultural functions. The Center for Epidemiological Studies-Depression Scale was used to assess depressive symptoms.

RESULTS

Significant gender differences in mean cognition scores (men: 25.8, women: 21.1; on a scale of 0-43) were observed. Two-way stratification between social engagement and depressive symptoms was significantly associated with cognitive functioning after controlling for selected explanatory factors. Older men with a low level of social engagements had significantly poor cognitive functioning (β=-1.12; 95% CI: -1.53 to -0.72) compared with men with a high level of social engagements. On the other hand, women with a higher level of social engagement performed poorly on cognitive tests (β=-1.54; 95% CI: -2.11 to -0.98) compared with men with higher social engagements. Three-way stratification between social engagement, gender and depressive symptoms suggests that social engagement's buffering effects are lower in women than in men. The Karlson-Holm-Breen method identified a significant confounding effect of depressive symptoms on the relationship between social engagement and cognitive functioning.

CONCLUSION

The positive association of social engagement with cognitive functioning was significantly confounded by depressive symptoms, suggesting the need for maintaining social relations that help improve mental health and cognitive functioning among older adults.

The association between purpose/meaning in life and verbal fluency and episodic memory: a meta-analysis of >140,000 participants from up to 32 countries

OBJECTIVES

Feelings of purpose and meaning in life are protective against consequential cognitive outcomes, including reduced risk of Alzheimer's disease and dementia. Purpose and meaning are likely to also be associated with cognitive functions on the pathway to dementia. The objective of the current research was to test whether both purpose in life and meaning in life are associated with higher verbal fluency and better episodic memory and whether these associations varied by sociodemographic characteristics or economic characteristics of the country.

DESIGN

Prospective meta-analysis of cross-sectional associations based on individual participant data.

SETTING

Established cohort studies with measures of either purpose in life or meaning in life and verbal fluency and episodic memory.

PARTICIPANTS

Across the cohorts, there were over 140,000 participants from 32 countries from North and South America, Europe, and the Middle East.

RESULTS

The meta-analysis indicated that purpose and meaning were associated with better performance on both the verbal fluency (meta-analytic partial r = .098, 95% confidence interval [CI] = .080, .116, p < .001) and episodic memory (r = .117, 95% CI = .100, .135, p < .001) task and that these associations were similar across measures of purpose in life and meaning in life. There was modest evidence that these associations were slightly stronger in relatively lower-income countries, and there was less consistent evidence that they varied by age, gender, or education.

DISCUSSION

These findings indicate a robust association between purpose/meaning and both verbal fluency and episodic memory across demographic groups and cultural context. Purpose/meaning may be a useful target of intervention for healthier cognitive aging.

Social network type and subsequent cognitive health among older Europeans

OBJECTIVES

One's personal social network constitutes a contextual framing factor for late-life cognitive function. This study examined the association between network type at baseline and changes in three cognitive measures: immediate recall, delayed recall, and fluency, two years hence, among Europeans aged 50 and older.

PARTICIPANTS

Data were taken from Waves four and five of the Survey of Health, Ageing, and Retirement in Europe of adults aged 50 and above (N = 50,071).

MEASUREMENTS

The latent class analysis was applied to a set of criterion variables. The procedure yielded five distinct network types: multi-tie (6%), family-rich (23%), close-family (49%), family-poor (12%), and friend-enhanced (10%). The network types were then regressed on the cognition measures at follow-up, controlling for the respective baseline cognition scores, as well as for age, gender, education, self-rated health, mobility difficulty, and country.

RESULTS

Respondents in family-poor network types had poorer cognition scores at follow-up, compared to those in the modal close-family network, while those in multi-tie networks had consistently better scores. The family-rich network and the friend-enhanced network also had a somewhat better cognitive function.

CONCLUSIONS

Having varied sources of network ties, e.g. friendship ties and/or several types of family relationships, is beneficial to the cognitive health of older adults over time. Networks based mainly on ties with relatives other than spouse and children, on the other hand, have poorer cognitive outcomes. Older people in this latter group face an increased risk for cognitive decline and should receive assistance in enhancing their interpersonal environments.

Trajectories of cognitive function and their determinants in older people: 12 years of follow-up in the Chinese Longitudinal Healthy Longevity Survey

BACKGROUND

Cognitive decline in advanced age is closely related to dementia. The trajectory of cognitive function in older Chinese is yet to be fully investigated. We aimed to investigate the trajectories of cognitive function in a nationally representative sample of older people living in China and to explore the potential determinants of these trajectories.

METHODS

This study included 2,038 cognitively healthy persons aged 65-104 years at their first observation in the Chinese Longitudinal Healthy Longevity Survey from 2002 to 2014. Cognitive function was measured using the Chinese version of the Mini-Mental State Examination (MMSE). Group-based trajectory modeling was used to identify potential heterogeneity of longitudinal changes over the 12 years and to investigate associations between baseline predictors of group membership and these trajectories.

RESULTS

Three trajectories were identified according to the following types of changes in MMSE scores: slow decline (14.0%), rapid decline (4.5%), and stable function (81.5%). Older age, female gender, having no schooling, a low frequency of leisure activity, and a low baseline MMSE score were associated with the slow decline trajectory. Older age, body mass index (BMI) less than 18.5 kg/m2, and having more than one cardiovascular disease (CVD) were associated with the rapid decline trajectory.

CONCLUSION

Three trajectories of cognitive function were identified in the older Chinese population. The identified determinants of these trajectories could be targeted for developing prevention and intervention strategies for dementia.