Social causation or social selection? The longitudinal interrelationship between poverty and depressive symptoms in China

https://doi.org/10.1016/j.socscimed.2020.112848Get rights and content

Highlights

  • Depression and poverty interact in a vicious cycle, which needs to be clarified.

  • Social selection and causation are possible pathways for depression and poverty.

  • Total and indirect effects of poverty on depression were found at baseline.

  • Depression directly drifted individuals into poverty at baseline and at follow-up.

  • Proactive interventions are needed to break the cycle of poverty and depression.

Abstract

Rationale

To our knowledge, no prior studies have investigated these bidirectional pathways between poverty and depressive symptoms to identify potential mechanisms.

Objective

This study aimed to investigate the interrelationship between poverty and depressive symptoms by examining two causal theories: social causation, which claims that the condition of poverty causes mental health disorders, and social selection, which suggests that those with poor mental health are more likely to drift into poverty.

Method

We obtained data from 17,250 adults aged 45 years or above from the China Health and Retirement Longitudinal Studies, first conducted in 2011–2012. Participants were tracked for 4 years, with baseline measurements taken as well as two 2-year follow-up visits. Structural equation models were used to examine the pathways in two directions at baseline, 2-year follow-up and 4-year follow-up.

Results

We found significant total effects and indirect effects of poverty on depressive symptoms at baseline, which were mediated through deterioration of household living conditions, decrease in social participation, and decline in life satisfaction. In the opposite direction, depressive symptoms directly led individuals to drift into poverty at baseline and at follow-up.

Conclusions

This study suggested that social causation and social selection may operate concurrently. Proactive interventions, especially ones focusing on modifiable protective factors that our findings identified as mediators in the link between poverty and depression, are urgently needed to break the vicious cycle of poverty and depression and create a virtuous cycle of increasing returns.

Introduction

Research has indicated that depression is predicted to be the leading cause of disease burden by 2030 (Mathers and Loncar, 2006). The burden of depression is increasing in aging populations in China, where a recent national survey showed almost 100 million people suffering from depression, including 10% of the country's total female population and 8% of the total male population (China Daily, 2016). Furthermore, the annual rising rate of depressive symptoms is approximately 2% per year (Chen et al., 2005; Qian et al., 2016). There is convincing evidence that depression can globally be considered a consequence of poverty (Darin-Mattsson et al., 2018; Flisher et al., 2007; Lund et al., 2010a, Lund et al., 2010b; Patel and Kleinman, 2003; Wickham et al., 2017), and often leads to income loss (Dohrenwend et al., 1992; Huddleston-Casas et al., 2009; Lund et al., 2013; Saraceno et al., 2005), implying that depression and poverty could interact in a vicious cycle (Haushofer and Fehr, 2014; Lund and Cois, 2018; Patel et al., 2010; Saraceno and Barbui, 1997). In spite of this information, little is still known about the interrelationship between poverty and depression (Anderson, 2018; Elwell-Sutton et al., 2019; Lund et al., 2018; Simmons et al., 2008), due to the fact that longitudinal studies remain sparse and causal mechanisms are difficult to identify (Cooper et al., 2012). Moreover, to our knowledge, no studies have investigated the complex pathways between poverty and depression to identify potential mechanisms and targets for interventions that address both issues.

Further, both issues appear to be more prominent in low- and middle-income countries (LMICs), in which depression makes a significant contribution to the burden of disease (Tampubolon and Hanandita, 2014). Yet, evidence on the interrelationship between poverty and depression in LMICs remains relatively scarce (Lund et al., 2010, 2018; Patel and Kleinman, 2003; Tampubolon and Hanandita, 2014). In China, widening income inequality and a rising poverty rate have gained increasing attention with the country's social transition following an open-market economy since the late 1970s (Luo and Zhu, 2008). Given the concerning relationship between poverty and depression, questions remain unanswered in China regarding whether poverty leads to a higher prevalence of depression, or if disabilities and increased healthcare expenses associated with depression lead individuals to drift into, or remain in, poverty.

Although the mechanisms involved are difficult to identify, two principal pathways have been postulated: social causation and social selection (also referred to “social drift”). The social causation hypothesis posits that the condition of poverty causes mental health disorders through financial stress, decreased social capital, increased exposure to poor living conditions, and unhealthy behaviors (Flisher et al., 2007; Lund et al., 2010a, Lund et al., 2010b; Patel and Kleinman, 2003; Wickham et al., 2017). Based on reviews of the existing literature, it can be asserted that a number of factors, including environmental and psychological factors, lie in the causal pathway between poverty and depression, and may influence variability in the relationship between poverty and depression. Living conditions, such as inadequate housing and less access to sanitation, are crucial in mediating the extent to which poverty-related variables affect the development of depressive symptoms (Gillis et al., 1991; Harpham, 1994). Social participation has been shown to be a protective factor for mental health disorders by facilitating access to resources for those living in poverty and converting resources into personal ability (Alang, 2014; Patel et al., 2006). Studies on psychological factors have broadly suggested that life satisfaction might negatively influence the incidence of depressive symptoms (Patel and Kleinman, 2003). It has further been suggested that the association between poverty and depression is linked to decreased levels of personal well-being due to a lack of resources, making it harder to leave behind the perceptions or experience of deprivation.

The social selection hypothesis argues that those with mental health disorders are more likely to drift into or remain in poverty due to increased health expenses, reduced productivity, loss of employment, and associated earnings (Dohrenwend et al., 1992; Saraceno et al., 2005). Previous studies found that reduced productivity among people with depressive symptoms could lead to higher unemployment rates and income loss (Saraceno et al., 2005). Increased health expenses associated with mental health disorders and comorbid physical illnesses are likely to drift people toward being economically deprived (Chiu et al., 2017). Poverty-related variables may be context-specific and dependent on the social and cultural context. Based on a literature review of longitudinal studies that examined the relationship between poverty and depression, we found that the majority examined the effect of poverty on depression (i.e., social causation; Flisher et al., 2007; Lund et al., 2010a, Lund et al., 2010b; Patel and Kleinman, 2003; Wickham et al., 2017), and limited studies examined the effects of depression on poverty (i.e., social selection or drift; Dohrenwend et al., 1992; Huddleston-Casas et al., 2009; Simmons et al., 2008). Hardly any studies simultaneously tested both of these pathways within the same population in LMICs (Elwell-Sutton et al., 2019).

Mental health has been included in the UN Sustainable Development Goals (SDGs) endorsed by all UN member nations, including China, which emphasize the inclusion of mental health care in universal health coverage (UN General Assembly, 2015). The acknowledgment of mental health in the SDGs is important, since mental health problems have significant and increasing social and economic costs (Chisholm et al., 2016). In China, management of mental health, including depression, has been incorporated into the public health service delivery system as part of China's health system reform, which was initiated in 2009 (Chen, 2009). Since depression is strongly socially determined, its burden is unlikely to be relieved by improved access to mental health care alone. Poverty eradication has always been at the heart of policy development worldwide as well as in China. In 2012, the 18th Congress of the Communist Party of China officially committed to comprehensively building a well-off society by achieving the goal of poverty reduction in which all impoverished rural populations should be out of poverty under the current standard by 2020 (State Council, 2012). This poverty elimination goal has the potential to reduce the burden of mental health disorders at the population level by addressing their upstream social determinants. For this reduction to occur, greater clarity is needed regarding the pathways by which depression and poverty interact in a negative cycle, and by what other factors these pathways are indirectly mediated. Thus, findings on this topic would be potentially significant from a policy perspective if the extent to which addressing these mediating factors might be able to reduce the burden of depression could be identified, and therefore reduce the incidence of poverty.

The objective of our study was to investigate: (1) whether poverty leads to depressive symptoms and how those potential pathways work; (2) whether depressive symptoms lead individuals to remain in or drift into poverty, and how those pathways work, with a view towards identifying potential mechanisms and targets for interventions that address both issues. A study on this topic will increase knowledge on specific mechanisms linking poverty and depressive symptoms which have not been identified in previous research, and clarify the pathways in the interrelationship between poverty and depressive symptoms.

Section snippets

Data and sample

Participants were enrolled in the China Health and Retirement Longitudinal Study (CHARLS), a biennial prospective observational study, nationally representative of Chinese adults aged ≥ 45 years and their spouses. All samples in the CHARLS were drawn in four stages: county-level sampling, neighborhood-level sampling, household-level sampling, and respondent-level sampling (Zhao et al., 2014). In the first stage, 150 county-level units were randomly selected with a

Characteristics of participants

Table 1 shows the characteristics of the cohort. Data from 17,250 participants aged 45 or above (mean age 59.1, SD = 9.9) were included for analysis. Of these, 48.7% were female, 27.0% had hypertension, 6.5% had diabetes, 10.0% had a recent accidental injury, and 3.0% had an intellectual disability. For participants who were female, rural, less educated, unemployed, and had no spouse, baseline CESD-10 scores were more likely to be higher and baseline poverty rates were higher. At baseline, the

Discussion

This study is, to our knowledge, the first nationally representative study to investigate the longitudinal interrelationship and intermediate steps between poverty and depressive symptoms. We found that social causation and social selection likely operate simultaneously, and relationships between poverty and depressive symptoms could be bidirectional. The large sample and the longitudinal design allowed for a direct assessment of temporality in the poverty-depressive symptoms relationship,

Conclusions

This study suggested that social causation and social selection may operate concurrently and empirically, supporting the notion that poverty and depressive symptoms interact in a vicious cycle in China. The interrelationship between poverty and depressive symptoms is recursive, although the bidirectional pathways were shown to have different mediating effects. A significant finding of our study was to provide specific mechanisms in the relationship between poverty and depressive symptoms,

Author contributions

Yinzi Jin: drafting the manuscript, study design, data analysis, and interpretation. Dawei Zhu: data analysis, and critical revision of article for important intellectual content. Ping He: study concept and design, data analysis, and critical revision of article for important intellectual content. All authors gave final approval of the version to be published.

Data availability statement

The datasets generated and analyzed during the current study are available in the CHARLS repository, http://charls.pku.edu.cn/pages/data/111/en.html.

Declaration of competing interest

None declared.

Acknowledgments

Source of Funding: This paper was supported by the Peking University's Start-up Fund (No. BMU2018YJ004). The study sponsor has no role in study design, data analysis and interpretation of data, the writing of manuscript, or the decision to submit the paper for publication.

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