Mediation and moderated mediation in the relationships among income condition, depression, cognition and residence among older adults in China

Indoor air pollution and cognitive function among older adults in India: a multiple mediation approach through depression and sleep disorders

BACKGROUND

Studies across multiple countries reveal that depression and sleep disorders can lead to cognitive decline. This study aims to speculate on the effect of different sources of indoor air pollution on cognition and to explore the mediation effect of depression and sleep disorders on cognition when exposed to indoor air pollution. We hypothesize that an older adult experiences higher cognitive decline from indoor pollution when mediated by depression and sleep disorders.

METHODS

We use data from Longitudinal Aging Study in India (LASI), 2017-2018, and employ a multiple mediation model to understand the relationship between indoor air pollution and cognition through sleep disorders and depression while adjusting for possible confounders. Sensitivity analysis was applied to see the effect of different sources of indoor pollution (cooking fuel, indoor smoke products, and secondhand smoke) on cognitive performance.

RESULTS

The effect of three sources of indoor pollutants on cognition increased when combined, indicating stronger cognitive decline. Unclean cooking practices, indoor smoke (from incense sticks and mosquito coils), and secondhand smoke were strongly associated with sleep disorders and depression among older adults. Indoor air pollution was negatively associated with cognitive health (β= -0.38) while positively associated with depression (β= 0.18) and sleep disorders (β= 0.038) acting as mediators. Sensitivity analysis explained 45% variability while adjusting for confounders.

CONCLUSION

The study lays a foundation for future investigations into the nexus of indoor pollution and mental health. It is essential to formulate policies to reduce exposure to varying sources of indoor air pollutants and improve screening for mental health services as a public health priority.

Memory and processing speed impairments in first-episode drug-naïve patients with major depressive disorder

BACKGROUND

Cognitive impairment, an intrinsic feature of major depressive disorder (MDD), affects daily and social functioning in depression patients. However, the cognitive impairment profile in MDD remains ambiguous because of the high heterogeneity of previous studies.

METHODS

Four cognitive domains, including memory, processing speed, executive function (EF), and attention, were assessed in 184 first-episode drug-naïve (FEDN) MDD patients and matched 71 healthy controls (HCs). The effects of demographic and depressive factors on cognitive performance were analyzed using various statistical methods, including multi-factor analysis of variance, Mann-Whitney U test, and Spearman's rank correlation. In addition, the impact of depression severity on cognitive function was further assessed using subgroup analyses and partial correlation analyses.

RESULTS

Age and education significantly impacted most cognitive performances, and depression severity appeared to influence processing speed. Moreover, cognitive scores in memory and processing speed, rather than in EF and attention, were significantly different between FEDN MDD patients and HCs after controlling for sex, age, educational attainment, household income, and body mass index.

LIMITATIONS

The number of HCs was relatively small, which may have slightly reduced the study's statistical power.

CONCLUSIONS

Age and educational attainment have confirmative confounding effects greater than those of depression in most cognitive functions. More importantly, memory and processing speed were impaired in MDD after strictly controlling for confounders. These findings provide new information for understanding the pattern of cognitive impairment and offer clues for further exploring the pathogenesis of cognitive abnormalities in MDD.

An analytical pathway of consumption expenditure with neighborhood deprivation and depression on cognitive health among elderly in India: A moderated mediation approach

BACKGROUND

This study aims to find the linkage between neighborhood deprivation and cognition with depression as a mediating factor while economic condition as a moderator.

METHODS

We have used the recent baseline wave-1 data of Longitudinal Aging Study in India (LASI), 2017-2018. The study was restricted to 60 and above population, consisting of males (14,931) and females (16,533). We have used moderated mediating model to understand the relationship between deprivation (X), cognition (Y) mediated through depression (M), moderated by economic condition (W), while controlling all possible confounders.

RESULTS

Neighborhood deprivation was positively associated with depression (β: 0.12; SE: 0.01) and inversely linked to cognition (β: -0.4; SE: 0.02). Deprivation had a strong indirect effect on cognition that was mediated by depression. Further, interaction of depression (M) and economic condition (W) was negatively associated (β = -0.03; SE: 0.01) with cognition (Y), indicating that lower economic section being more depressed with lower cognitive function.

LIMITATIONS

The study failed to capture other mental health aspects like stress and anxiety using the Depression, Anxiety and Stress Scale-21 items (DASS-21).

CONCLUSIONS

This study has found a link between higher economic condition with low deprivation and depression. Older individuals with better financial situation have improved cognitive level than their counterparts, who are also depressed. This study provides an opportunity to conduct future research on cognitive health in the face of population aging in India.

Examining the impact of socioeconomic status, demographic characteristics, lifestyle and other risk factors on adults' cognitive functioning in developing countries: an analysis of five selected WHO SAGE Wave 1 Countries

BACKGROUND

Though extensive studies have been conducted on assessing the predictors of cognitive functioning among older adults in small community-based samples, very few studies have focused on understanding the impact of socioeconomic status (SES), demographic characteristics and other risk factors such as lifestyle and chronic diseases on the cognitive functioning among adults of all ages in a nationally representative population-based sample across low- and middle-income countries. This study, therefore, seeks to evaluate the impact of SES, demographic characteristics and risk factors on the cognitive functioning of adults across all ages in five selected developing countries.

METHODS

Data from 12,430 observations obtained from the WHO Study on Global AGEing and Adult Health (SAGE) Wave 1; consisting of 2,486 observations each for China, Ghana, India, the Russian Federation, and South Africa, were used for the study. A meta-regression and a five-step hierarchical linear regression were used to analyze the data, with cognitive functioning as the dependent variable. Independent variables used in this study include SES; assessed by household income and education, demographic characteristics, other risk factors such as lifestyle, self-reported memory difficulty and chronic diseases.

RESULTS

This study found that SES and lifestyle significantly predicted cognitive functioning in all the five selected countries as obtained by the pooled results of the meta-regression analysis. The hierarchical linear regression results also revealed that demographic characteristics such as age, type of residency, and self-reported memory difficulty significantly impact cognitive functioning in China, Ghana, Russia, and South Africa.

CONCLUSION

The findings in this study provide new insights for policymakers, caregivers, parents, and individuals, especially those in developing countries, to implement policies and actions targeted at improving SES and eliminating risk factors associated with cognitive decline, as these measures could help improve the cognitive functioning among their populations.

Does Participation in Local Non-agricultural Employment Improve the Mental Health of Elderly Adults in Rural Areas? Evidence From China

A rising rate of suicide among the elderly in rural China has been recognized to be triggered by mental health-associated factors. This study uses 3,397 sampled rural elderly adults from China Labor-force Dynamic Survey in 2016 to explore the response mechanism through which non-agricultural employment participation by the elderly adults in rural China can influence their mental health. Utilizing the Multivariate Regression, Instrumental Variable and Propensity Score Matching methods, we find that, the rural elderly adults who participate in local non-agricultural employment significantly improve their mental health. Self-employment tends to have a greater positive contribution to the mental health of the elderly population than waged employment. Further, work income, need for belongingness and respect, and human capital development significantly mediates the influence of participation in local non-agricultural employment on the mental health of the elderly adults. Finally, we put forward relevant policy suggestions to improving the mental health of the elderly in the countryside.

Risk factors for suicidal behavior in late-life depression: A retrospective preliminary clinical study

AIM

To explore the risk factors associated with suicidal behavior (SB) using logistic regression analysis and the propensity score matching (PSM) method among Chinese patients suffering from late-life depression (LLD).

METHOD

Patient information sheets were retrieved with the International Classification of Diseases, Tenth Revision (ICD-10) code from an electronic database that comprised patient medical information. Herein, we set SB as a dependent variable, and gender, marital status, monthly income, quality of interpersonal relationships, hobbies, impulsivity, severity of depression, psychiatric symptoms or not, and having histories of smoking, drinking, major mental trauma as independent variables according to clinical experience and previous findings. For uncertain independent risk factors associated with SB generated by logistic regression analysis, PSM was performed for further verification.

RESULTS

The differences between the SB group and non-SB group for marital status, severity of depression, a history of drinking, and a history of major mental trauma were found to be statistically significant in univariate comparisons (P < 0.05); binary logistic regression analysis and PSM analysis showed that the severity of depression, a history of drinking, and a history of major mental trauma were independent risk factors associated with SB of patients with LLD with an odds ratio greater than one.

CONCLUSION

The severity of depression, a history of drinking, and a history of major mental trauma were independently associated with the occurrence of SB of patients with LLD in China. Further longitudinal and prospective studies are warranted to examine the dynamic changes of confounding risk factors. Geriatr Gerontol Int 2021; 21: 849-854.