State-Level Income Inequality and County-Level Social Capital in Relation to Individual-Level Depression in Middle-Aged Adults: A Lagged Multilevel Study.

Saloni Dev,Daniel Kim

doi:10.3390/ijerph17155386

Abstract

In the US, the incidence of depression and suicide have followed escalating trends over the past several years. These trends call for greater efforts towards identifying their underlying drivers and finding effective prevention strategies and treatments. One social determinant of health that plausibly influences the risk of depression is income inequality, the gap between the rich and poor. However, research on this association is still sparse. We used data from the National Longitudinal Survey of Youth 1979 and the US Census to investigate the multilevel lagged associations of state-level income inequality with the individual-level odds of depression in middle-aged adults, controlling for state- and individual-level factors. We also examined the independent associations of county-level social capital with depression and explored whether it mediated the income inequality relationship. Higher income inequality at the state level predicted higher odds of individual-level depression nearly 2 decades later [OR for middle vs. lowest tertile of income inequality = 1.35 (95% CI: 1.02, 1.76), OR for highest vs. lowest tertile = 1.34 (95% CI: 1.01, 1.78)]. This association was stronger among men than women. Furthermore, there was evidence that county-level social capital independently predicted depression and that it mediated the income inequality association. Overall, our findings suggest that policies attenuating levels of income inequality at the US state level and that leverage social capital may protect against one’s likelihood of developing depression.

Highlights

In 2017, 17.3 million adults in the US experienced at least one episode of major depression [1].Depression is a leading cause of disability, mortality, and has been associated with other high-burden health conditions such as cardiovascular diseases [2–4]
17.4% of the study sample reported having depression on the 50-and-over module. Compared to those residing in states belonging to the lowest tertile of state-level income inequality, there was a higher odds of depression measured nearly two decades later among those living in states belonging to the middle tertile (OR = 1.35, 95% CI: 1.02, 1.76) and highest tertile (OR = 1.34, 95% CI: 1.01, 1.78; see, Table 2, Model 1)
Our findings suggest that higher levels of income inequality at the US state level are linked to a higher odds of individual-level depression nearly 2 decades later

Summary

Introduction

Depression is a leading cause of disability, mortality, and has been associated with other high-burden health conditions such as cardiovascular diseases [2–4]. To further reduce the high burden of depression, there is a fundamental need to identify its root causes. Using a social determinants of health lens, identifying the role of societal conditions in influencing the risk of depression holds particular promise. The unequal distribution of valued resources, services, and positions within a society [5], has been identified as a major social determinant of common mental illnesses including depression [6]. In the US, income inequality has been growing over the past several decades, with the top 10 percent of the population averaging nearly nine times as much income as the bottom 90 percent [8].

Methods

Results

Conclusion