Do cognitive and non-cognitive abilities mediate the relationship between air pollution exposure and mental health?

Associations between parental adherence to healthy lifestyles and cognitive performance in offspring: A prospective cohort study in China

BACKGROUND

Previous studies have reported associations of specific maternal and paternal lifestyle factors with offspring's cognitive development during early childhood. This study aimed to investigate the prospective associations between overall parental lifestyle and offspring's cognitive performance during adolescence and young adulthood in China.

METHODS

We included 2531 adolescents aged 10-15 years at baseline in 2010 from the China Family Panel Studies. A healthy parental lifestyle score (ranged 0-5) was constructed based on the following five modifiable lifestyle factors: Smoking, drinking, exercise, sleep, and diet. Generalized estimating equation models were used to examine the association between baseline parental healthy lifestyle scores and offspring's fluid and crystallized intelligence in subsequent years (2012, 2014, 2016, and 2018).

RESULTS

Offspring in the top tertile of parental healthy lifestyle scores performed better in overall fluid intelligence (multivariable-adjusted β = 0.53, 95% confidence interval [CI]: 0.29-0.77) and overall crystallized intelligence (multivariable-adjusted β = 0.35, 95% CI: 0.16-0.54) than those in the bottom tertile of parental healthy lifestyle scores. The results were similar after further adjustment for the offspring's healthy lifestyle scores and persisted across the subgroups of parental socioeconomic status. Additionally, maternal and paternal healthy lifestyle scores were independently associated with better offspring's cognitive performance, with significant contribution observed for paternal never-smoking, weekly exercise, and diversified diet. When both parents and offspring adhered to a healthier lifestyle, we observed the highest level of the offspring's overall crystallized intelligence.

CONCLUSIONS

Our study indicates that parental adherence to a healthier lifestyle is associated with significantly better offspring's cognitive performance during adolescence and early adulthood, regardless of socioeconomic status. These findings highlight the potential cognitive benefits of promoting healthy lifestyles among parents of adolescents.

Non-Cognitive Adaptive Resourcefulness: Scrutiny of Its Multidimensionality and Nomological Validity

Recent research has observed that Mental Toughness, Optimal Regulation, and Self-Efficacy share core features and variance. Investigators have named this commonality Non-Cognitive Adaptive Resourcefulness (NCAR). The NCAR validation study reported that the construct possesses promising psychometric properties, however, further research is required to replicate and extend these findings. Acknowledging this, the present paper using a UK-based sample of 1998 participants (Mage = 40 years, range 18-83), tested the NCAR model against competing alternatives (multidimensional and one-factor solutions), and assessed the nomological validity of NCAR in relation to Perceived Stress and Anxiety Control. Participants completed the self-report study measures online. Exploratory structural equation modelling revealed that a bifactor solution represented data more effectively than one-factor and multi-factor alternatives. Additionally, a structural equation model found that NCAR significantly predicted Perceived Stress (subfactors of Distress and Coping) and Anxiety Control (subfactors of Emotional Control, Threat Control, and Stress Control). Moreover, NCAR predicted PSS Coping and Emotional Control to a greater extent than the specific bifactors (Mental Toughness, Optimal Regulation, and Self-Efficacy). This suggested that NCAR comprises an underpinning, positive psychological energy that facilitates coping. Particularly, an enabling resource that enhances the capacity to thrive under pressure and retain emotional control in demanding and trying circumstances.

Association between depression status in adolescents and cognitive performance over the subsequent six years: A longitudinal study

BACKGROUND

Adolescent depression is a common mental health problem and is sometimes associated with cognitive impairments. However, existing research regarding the association between depression status in adolescents and cognitive performance over the subsequent years is relatively paucity.

METHODS

The present study used longitudinal data from four waves (2012, 2014, 2016, and 2018) of the China Family Panel Studies (CFPS) to explore the associations between adolescent depression status in 2012 and cognitive performance (measured by immediate word recall, delayed word recall, number series tests, mathematics, and vocabulary) over the subsequent years. A total of 1055 (51.72 %), 1115 (54.66 %), and 879 (43.09 %) of the 2040 adolescents identified in 2012 were followed up in 2014, 2016, and 2018, respectively.

RESULTS

We found that adolescent depression status consistently showed a negative association with cognitive performance at the measurement points over six years. The associations were retained for most cognitive outcomes after controlling for a variety of confounding factors (adolescents, parental, and family characteristics).

CONCLUSIONS

The findings of this study provide more evidence of the association between depression status in adolescents and cognitive performance. Additionally, it highlights the importance of focusing on cognitive impairment in patients with depression more broadly, especially during adolescence, a critical period for cognitive development.

Assessing the causal effect of long-term exposure to air pollution on cognitive decline in middle-aged and older adults - Empirical evidence from a nationwide longitudinal cohort

Air pollution remains a risk factor for the global burden of disease. Middle-aged and older people are more susceptible to air pollution because of their declining physical function and are more likely to develop diseases from long-term air pollution exposure. Studies of the effects of air pollution on cognitive function in middle-aged and older adults have been inconsistent. More representative and definitive evidence is needed. This study analysed data from the Chinese Family Panel Study, an ongoing nationwide prospective cohort study, collected in waves 2014, 2016 and 2018. Rigorously tested instrument was selected for analysis and participants' PM_2.5 and instrument exposures were assessed using high-precision satellite data. The causal relationship between long-term exposure to air pollution and poor cognitive function in middle-aged and older adults was investigated using the Correlated Random Effects Control Function (CRE-CF) method within a quasi-experimental framework. This study included a total of 7042 participants aged 45 years or older. A comparison of CRE-CF with other models (OLS model, ordered probit model, and ordered probit-CRE model) demonstrated the necessity of using CRE-CF given the endogeneity of air pollution. The credibility and validity of the instrumental variable were verified. In the CRE-CF model, long-term exposure to PM_2.5 was found to accelerate cognitive decline in middle-aged and older adults (coefficients of -0.159, -0.336 and -0.244 for the total cognitive, verbal and mathematical scores, respectively). Taken together, these results suggest that chronic exposure to ambient air pollution is associated with cognitive decline in middle-aged and older adults, which highlights the need for appropriate protective policies.

Air pollution and human cognition: A systematic review and meta-analysis

BACKGROUND

This systematic review summarises and evaluates the literature investigating associations between exposure to air pollution and general population cognition, which has important implications for health, social and economic inequalities, and human productivity.

METHODS

The engines MEDLINE, Embase Classic+Embase, APA PsycInfo, and SCOPUS were searched up to May 2022. Our inclusion criteria focus on the following pollutants: particulate matter, NOx, and ozone. The cognitive abilities of interest are: general/global cognition, executive function, attention, working memory, learning, memory, intelligence and IQ, reasoning, reaction times, and processing speed. The collective evidence was assessed using the NTP-OHAT framework and random-effects meta-analyses.

RESULTS

Eighty-six studies were identified, the results of which were generally supportive of associations between exposures and worsened cognition, but the literature was varied and sometimes contradictory. There was moderate certainty support for detrimental associations between PM_2.5 and general cognition in adults 40+, and PM_2.5, NOx, and PM₁₀ and executive function (especially working memory) in children. There was moderate certainty evidence against associations between ozone and general cognition in adults age 40+, and NOx and reasoning/IQ in children. Some associations were also supported by meta-analysis (N = 14 studies, all in adults aged 40+). A 1 μg/m³ increase in NO₂ was associated with reduced performance on general cognitive batteries (β = -0.02, p < 0.05) as was a 1 μg/m³ increase in PM_2.5 exposure (β = -0.02, p < 0.05). A 1μgm³ increase in PM_2.5 was significantly associated with lower verbal fluency by -0.05 words (p = 0.01) and a decrease in executive function task performance of -0.02 points (p < 0.001).

DISCUSSION

Evidence was found in support of some exposure-outcome associations, however more good quality research is required, particularly with older teenagers and young adults (14-40 years), using multi-exposure modelling, incorporating mechanistic investigation, and in South America, Africa, South Asia and Australasia.

Mental toughness in the Football Association Women's Super League: Relationships with playing experience, perceptions of club infrastructure, support mechanisms and self-esteem

Previous research reports a positive association between possession of mental toughness (MT) and high performance in sportspersons. However, the extent to which MT is related to playing experiences and appreciation of club environment in elite women's football has received only limited research attention. Accordingly, the present study investigated MT in the context of the English Football Association Women's Super League (WSL). Specifically, this paper examined relationships between level of MT and external (playing experience, perceptions of club infrastructure, and appreciation of support mechanisms) and internal (self-esteem) factors. A sample of 63 elite female professional football players from the WSL, aged between 18 and 35 years (mean = 25.87, SD = 4.03), completed self-report measures. To objectively validate self-ratings, congruence between self and peer-rated was assessed. This revealed a strong degree of consistency. Subsequent analysis found positive correlations between MT, playing experience (number of years playing football, NoY; and highest level of football achieved, HLA), and External Support. Additionally, Self-Esteem correlated positively with MT, NoY, HLA, and External Support. Moderation analysis found MT interacted with NoY and predicted greater levels of Self-Esteem. Players with lower and mean MT, and more years as a professional were more likely to possess higher Self-Esteem (vs. less years). These outcomes indicated important relationships between MT, External Support, and Self-Esteem. Accordingly, WSL clubs can potentially apply the results of this study to enhance positive player mindset.

Association of adolescent self-esteem in 2014 and cognitive performance in 2014, 2016, and 2018: a longitudinal study

Background

Cognition has long been regarded as a significant factor influencing individuals' lives. Prior studies have underscored that self-esteem is associated with cognition, and there exists a knowledge gap regarding whether self-esteem remains associated with subsequent cognitive performance during adolescence, a crucial period for neurological development and influencing adult outcomes.

Methods

We conducted this population-based study using longitudinal data stretching three waves (2014, 2016, and 2018) of surveys from the nationally representative China Family Panel Studies (CFPS) to explore the association between adolescents' self-esteem in 2014 and cognitive performance in 2014, 2016, and 2018.

Results

The results of the present study showed that self-esteem during adolescence in 2014 was significantly associated with cognitive performance in 2014, 2016, and 2018. This association remained robust after an extensive range of covariate adjustments (e.g., adolescents, parental, and family characteristics).

Conclusion

The findings in this study provide further insight into the understanding of the related factors for cognitive development across the life course and highlight the importance of improving individual self-esteem during adolescence.

Examining what Mental Toughness, Ego Resiliency, Self-efficacy, and Grit measure: An exploratory structural equation modelling bifactor approach

Despite conceptual similarities among the established non-cognitive constructs of Mental Toughness, Ego Resiliency, Self-efficacy, and Grit, preceding research typically considered these as adversary rather than complementary and potentially additive. Subsequently, comparatively few studies have examined these together. This paper, via two independent studies, examined commonality within Mental Toughness, Ego Resiliency, Self-efficacy, and Grit. This identified key elements that contribute to a broad, non-cognitive, resource-based construct. Study 1 (N = 2137) assessed shared variance among the non-cognitive constructs relative to a general factor. Study 2 (N = 1148) evaluated the replicability of the results from Study 1 and examined measurement invariance. Respondents completed established self-report measures indexing the study variables. Exploratory structural equation modelling bifactor analyses consistently revealed that Mental Toughness, the Ego-Resiliency Optimal Regulation subscale, and Self-efficacy loaded highly on a general factor, which the authors labelled as Non-Cognitive Adaptive Resourcefulness (NCAR). Invariance analyses supported the stability of this model across study context. This paper advanced conceptual understanding of the core shared features of independent non-cognitive constructs. The authors discuss the potential of NCAR and advocate the need for further research.

An educational approach for early student self-assessment in clinical periodontology

BACKGROUND

Self-assessment is a mandated educational requirement for use in dental undergraduate programmes. It is weakly supported for use in early clinical training and studies are criticized for the conceptual and methodology shortfalls. The aim of the study was to compare the alignment of student self-assessment to both staff assessment and written exams in early clinical training using an educational approach.

METHODS

In 2014-2015, 55 third-year dental students completed three educational sessions comprising of (a) classroom teaching (lecture, video) with post-lesson written exam and (b) clinical activity with student self-assessment, staff assessment and student reflection. An intra-individual analysis approach, staff validation, and student scoring standardization were implemented. Cognitive (clinical competency) and non-cognitive (professionalism) items were separated in the analyses.

RESULTS

There were medium correlations (Spearman's rho, r) between student self-assessment and staff assessment scores for cognitive items (r, 0.32) and for non-cognitive items (r, 0.44) for all three combined sessions. There were large correlations for individual sessions. Compared to the post-lesson written exam, students showed small correlation (r, 0.22, 0.29) and staff showed medium correlation (r, 0.31, 0.34) for cognitive and non-cognitive items. Students showed improvements in their mean scores for both cognitive (t-test; p > 0.05) and non-cognitive items (t-test; p = 0.000). Mean scores of students were not different statistically from that of staff (p > 0.05).

CONCLUSIONS

Students may adequately act as self-assessors at the beginning of their clinical work in periodontology. Self-assessment may potentially improve the clinical performance. Self-assessment may be nurtured through clear guidelines, educational training strategies, feedback and reflection leading to better evaluative judgement and lifelong learning.

Population Health Effects of Air Pollution: Fresh Evidence From China Health and Retirement Longitudinal Survey

The effects of air pollution on population health are currently a hot topic. However, few studies have examined the physical and mental health effects of air pollution jointly in China. Using data from the China Health and Retirement Longitudinal Study (CHARLS) in 2015 and 2018, this study explores how air pollution affects the physical and mental health of middle-aged and elderly residents. The empirical results highlight that air pollution can negatively affect both physical and mental health. In terms of physical health, those exposed to chronic shock are likely to suffer more adverse effects from air pollution than those exposed to acute shock. In terms of mental health, those exposed to depression suffer greater adverse effects than those exposed to episodic memory and mental cognition. Besides, heterogeneity analysis also shows that air pollution affects the mental and physical health of males more than females. Furthermore, the increase in air pollution is expected to result in huge hospitalization costs. Therefore, the Chinese government should formulate differentiated public health policies to reduce the effects of air pollution on the health of middle-aged and elderly residents.

Silent but Damaging: Exploring the Link Between Air Pollution and Vocational and General Well-Being

Air pollution has become a daunting challenge with the potential to endanger people’s lives across the globe. However, little is known about the psychological and vocational implications of air pollution. Drawing on feeling-as-information theory, we investigate the within-person relationships of ambient air pollution with vocational and general well-being outcomes (i.e., career choice anxiety and state optimism) through the mediating mechanism of mood state. We tested our hypotheses using an experience sampling method (ESM) with survey data from 67 undergraduate students in South Korea collected over 10 consecutive days. Results showed that daily ambient air pollution predicted higher career choice anxiety and lower state optimism via an increased negative mood. Furthermore, the indirect relation of air pollution with career choice anxiety was found to be stronger for individuals with lower family socioeconomic status. In a supplementary study, we interviewed 16 undergraduate students in South Korea to explain the ESM results in greater depth. Theoretical and practical implications, as well as study limitations, are discussed.

Community Environment Perception on Depression: The Mediating Role of Subjective Social Class

Depression has become a major social issue of global concern, which has seriously threatened the quality of an individual’s life. Although the relationship between community environment and depression has aroused heated debate, the empirical research on the relationship between community environment perception and public depression is still relatively insufficient. Data for this study are from China Family Panel Studies in 2016, which were conducted by the institute of Social Science Survey, Peking University. This paper has tested group differences in the influence of community environment on public depression, as well as the mediating role of subjective social class between community environment perception and depression, so as to further explore the social psychological effect of community environment. The empirical study found that there are group differences in the impacts of community environment perception on depression. Specifically, men, rural residents, and people aged 60 and under are more likely to be depressed which were affected by the perception of community environment. Furthermore, we have found that the subjective social class can partly mediate community environment perception and depression. That is to say, the perception of community environment can induce depression by influencing the individual’s subjective social class. Among them, community living environment and community public facilities have the greatest impact, community emotional attachment and community security situation have the second impact, and neighborhood mutual aid and neighborhood relationship have the least impact. In other words, the community environment is deeply endowed with a social psychological effect. To ameliorate the public’s depression, it is necessary to consider the construction of community physical environment and the cultivation of harmonious community culture as powerful measures not to be ignored. In short, the important role of community environmental intervention in alleviating the public’s depression caused by social class cognition deserves attention.

Effects of Environmental Quality Perception on Depression: Subjective Social Class as a Mediator

Although the relationship between environment and public depression has aroused heated debate, the empirical research on the relationship between environmental quality perception and public depression is still relatively insufficient. This paper aims to explore the influence of environmental quality perception on public depression and the mediating role of subjective social class between environmental quality perception and public depression. Using the China Family Panel Studies data of 2016 for empirical analysis, this study’s results show that environmental quality perception has a significant effect on public depression and subjective social class also has a significant effect on public depression. In addition, we found that subjective social class can play a partial mediating role between environmental quality perception and public depression, and the intermediary effect only comes from the contribution of the perception of living environmental quality, not the perception of overall environmental quality. That is to say, the perception of living environment quality deeply affects the subjective social class, and then induces public depression. In order to alleviate the relationship between environmental quality and public depression, it is recommended that the state environmental protection department and civil affairs department strengthen the improvement of public living environment so as to promote individual subjective social class and reduce the risk of public depression. Moreover, it is suggested that research with longitudinal design and comprehensive indicators be undertaken in the future.

Effects of pollution on adolescent mental health: a systematic review protocol

BACKGROUND

Whilst there is little uncertainty about the deleterious impact of pollution on human and planetary health, pollution's impact on adolescent mental health is less well understood. This is particularly true for young people in underdeveloped and developing world contexts, about whom research is generally lacking. Furthermore, although adolescent resilience continues to be a research priority, little attention has been paid to adolescent pathways of resilience in the face or aftermath of pollution exposure. The objective of this study will be to examine the associations between pollution and mental health in 10- to 24-year-olds (i.e. adolescents).

METHODS

We designed and registered a study protocol for a systematic review of studies which link pollution and mental health in adolescents. We will include observational studies (e.g. cohort, case-control, time series analyses) that assess the associations between exposure to any form of pollution and the mental health of 10- to 24-year-olds. The primary outcome will be symptoms associated with neurodevelopmental disorders; disruptive, impulse-control, and conduct disorders; depressive disorders; anxiety disorders; substance disorders; and schizophrenia. No secondary outcomes will be considered. Literature searches will be conducted in multiple electronic databases (from inception onwards), including PubMed, MEDLINE, SCOPUS, Web of Science, CINAHL, PsycINFO, SciELO, ERIC, and Africa-Wide. Two investigators will independently screen all citations, full-text articles, and abstract data. The methodological quality (or bias) of included studies will be appraised using appropriate tools. We will provide a narrative synthesis of the evidence.

DISCUSSION

This systematic review will evaluate the evidence on the associations between pollution and the mental health of 10- to 24-year-olds. Our findings will be of potential interest to multiple audiences (including adolescent patients/clients, their families, caregivers, healthcare professionals, scientists, and policy makers) and could be used to develop prevention and intervention strategies as well as focus future research. Results will be published in a peer-reviewed journal.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020176664.

Outdoor air pollution exposure and inter-relation of global cognitive performance and emotional distress in older women

The interrelationships among long-term ambient air pollution exposure, emotional distress and cognitive decline in older adulthood remain unclear. Long-term exposure may impact cognitive performance and subsequently impact emotional health. Conversely, exposure may initially be associated with emotional distress followed by declines in cognitive performance. Here we tested the inter-relationship between global cognitive ability, emotional distress, and exposure to PM2.5 (particulate matter with aerodynamic diameter <2.5 μm) and NO2 (nitrogen dioxide) in 6118 older women (aged 70.6 ± 3.8 years) from the Women's Health Initiative Memory Study. Annual exposure to PM2.5 (interquartile range [IQR] = 3.37 μg/m3) and NO2 (IQR = 9.00 ppb) was estimated at the participant's residence using regionalized national universal kriging models and averaged over the 3-year period before the baseline assessment. Using structural equation mediation models, a latent factor capturing emotional distress was constructed using item-level data from the 6-item Center for Epidemiological Studies Depression Scale and the Short Form Health Survey Emotional Well-Being scale at baseline and one-year follow-up. Trajectories of global cognitive performance, assessed by the Modified-Mini Mental State Examination (3MS) annually up to 12 years, were estimated. All effects reported were adjusted for important confounders. Increases in PM2.5 (β = -0.144 per IQR; 95% CI = -0.261; -0.028) and NO2 (β = -0.157 per IQR; 95% CI = -0.291; -0.022) were associated with lower initial 3MS performance. Lower 3MS performance was associated with increased emotional distress (β = -0.008; 95% CI = -0.015; -0.002) over the subsequent year. Significant indirect effect of both exposures on increases in emotional distress mediated by exposure effects on worse global cognitive performance were present. No statistically significant indirect associations were found between exposures and 3MS trajectories putatively mediated by baseline emotional distress. Our study findings support cognitive aging processes as a mediator of the association between PM2.5 and NO2 exposure and emotional distress in later-life.

The factors associated with distress following exposure to smoke from an extended coal mine fire

In February 2014, the coalmine adjacent to the Hazelwood Power Station in the Latrobe Valley of Victoria, Australia, caught fire, with residents from the nearby town of Morwell and the wider area exposed to smoke for six weeks. Although there was evidence linking the mine-fire event with psychological distress, no studies have evaluated the degree of distress in relation to the level of smoke exposure. We aimed to investigate the exposure-response relationship between particulate matter 2.5 μm or less in diameter (PM_2.5) released during the Hazelwood mine fire event and long-term symptoms of posttraumatic distress in the affected community, including the consideration of other key factors. A total of 3096 Morwell residents, and 960 residents from the largely unexposed comparison community of Sale, were assessed for symptoms of posttraumatic distress 2.5 years after the Hazelwood incident using the Impact of Events Scale-Revised (IES-R). Individual-level PM_2.5 exposure was estimated by mapping participants' self-reported location data on modelled PM_2.5 concentrations related to the mine fire. Multivariate linear regression was used to evaluate the exposure-response relationship. Both mean and peak exposure to mine fire-related PM_2.5 were found to be associated with participant IES-R scores with an interaction effect between age and mean PM_2.5 exposure also identified. Each 10 μg/m³ increase in mean PM_2.5 exposure corresponded to a 0.98 increase in IES-R score (95% CI: 0.36 to 1.61), and each 100 μg/m³ increase in peak PM_2.5 exposure corresponded to a 0.36 increase (95% CI: 0.06 to 0.67). An age-effect was observed, with the exposure-response association found to be stronger for younger adults. The results suggest that increased exposure to PM_2.5 emissions from the Hazelwood mine fire event was associated with higher levels of psychological distress associated with the mine fire and the most pronounced effect was on younger adults living in the affected community.

Effects of Progressive Resistance Training on Cognition and IGF-1 Levels in Elder Women Who Live in Areas with High Air Pollution

The aim of this study was to determine the effects of a muscular strength programme on the levels of insulin-like growth factor-1 (IGF-1) and cognitive status in elder women with mild cognitive impairment who lived in areas of high air pollution. A total of 157 women participated in the study, distributed in four groups: Active/Clean (AC n = 38) and Active/Pollution (AP n = 37), who carried out a progressive resistance training programme for 24 months, and Sedentary/Clean (SC n = 40) and Sedentary/Pollution (SP n = 42). Maximum strength in the upper and lower limbs (1RM), cognition (Mini-Mental Scale Examination (MMSE)) and blood IGF-1 were evaluated. At the beginning of the intervention, there were no differences between the groups in the assessed variables. The active groups which carried out the resistance training programme (AC and AP), registered better results in IGF-1 than the sedentary groups. These differences were statistically significant in AC vs. SC (p < 0.01) and AP vs. SC (p < 0.05). Regarding MMSE, group AC registered the highest score increases (+8.2%) (significantly better than the other groups), while group SP worsened (−7%) significantly compared to the other three groups. In conclusion, resistance training had a positive effect on IGF-1, while sedentary behaviour and air pollution had a negative effect on cognitive status.

The effect of air pollution on children's migration with parents: evidence from China

Population migration and air pollution are inevitable problems in the process of urbanisation. With the continuous advancement of urbanisation, the trends in family migration have become more prominent, and children's migration with parents has become an important indicator reflecting the speed, structure, and quality of urbanisation. Our analysis relies on data from China Migrants Dynamic Survey to estimate the effect of air pollution on children's migration with parents. After using the instrumental variables to correct the possible endogeneity, we found that air pollution has a significant negative effect on children's migration with parents. Through further analysis, air pollution mainly affects migrant children by reducing the settlement intention of the migrants, the house purchase tendency in the influx city, and the income level. After replacing the independent variables, using narrow samples, and considering heterogeneity differences, this paper's conclusions remain robust. Therefore, in the process of urbanisation development, it is important to coordinate the relationship between the environment and the population, and it has an important significance to delay the demographic dividend recession and promote sustainable economic development in developing countries.