Income inequality and depression: a systematic review and meta‐analysis of the association and a scoping review of mechanisms

Abstract

Most countries have witnessed a dramatic increase of income inequality in the past three decades. This paper addresses the question of whether income inequality is associated with the population prevalence of depression and, if so, the potential mechanisms and pathways which may explain this association. Our systematic review included 26 studies, mostly from high-income countries. Nearly two-thirds of all studies and five out of six longitudinal studies reported a statistically significant positive relationship between income inequality and risk of depression; only one study reported a statistically significant negative relationship. Twelve studies were included in a meta-analysis with dichotomized inequality groupings. The pooled risk ratio was 1.19 (95% CI: 1.07-1.31), demonstrating greater risk of depression in populations with higher income inequality relative to populations with lower inequality. Multiple studies reported subgroup effects, including greater impacts of income inequality among women and low-income populations. We propose an ecological framework, with mechanisms operating at the national level (the neo-material hypothesis), neighbourhood level (the social capital and the social comparison hypotheses) and individual level (psychological stress and social defeat hypotheses) to explain this association. We conclude that policy makers should actively promote actions to reduce income inequality, such as progressive taxation policies and a basic universal income. Mental health professionals should champion such policies, as well as promote the delivery of interventions which target the pathways and proximal determinants, such as building life skills in adolescents and provision of psychological therapies and packages of care with demonstrated effectiveness for settings of poverty and high income inequality.

Prevention of depression will only succeed when it is structurally embedded and targets big determinants

“…Negative affectivity and self‐control are especially important, given the prospective significance of early‐onset phobia, hyperactivity and oppositional‐defiant behavior. Also of interest, but less thoroughly investigated, are the mental health effects of distal socio‐economic and cultural factors, such as inferior social status, income inequality, migration, and their effect mediators.…”

Agricultural wealth better predicts mental wellbeing than market wealth among highly vulnerable households in Haiti: Evidence for the benefits of a multidimensional approach to poverty

“…First, in the full range of rural, peri‐urban, and urban areas, availability of crops and animals for household consumption can provide food security (Ayenew et al, ; Sen, ) which, in turn, has shown associations with improved mental health (Weaver & Hadley, ). More indirectly, livestock and land can contribute to the household income, which also has shown associations with improved mental health (Berinyuy & Fontem, ; Burns, Tomita, & Lund, ; Fone et al, ; Hruschka et al, ; Vikram Patel et al, ; Pickett & Wilkinson, ). Beyond such direct effects on food security, nutrition, and income, success in agricultural activities might also enhance social capital and status to provide further buffering effects for mental health (Glass et al, ; Grabe et al, ; Hoke, ; Nanama & Frongillo, ; Pike & Patil, ; Rao, ).…”

Increase value and reduce waste in research on psychological therapies

“…Determining which questions have value is more challenging, since allocating resources to any priority comes at the cost of divesting them from alternatives. For example, the focus on mechanistic approaches to psychological treatments could distract from other, pervasive determinants of mental disorders, like poverty (Deighton, et al, 2019), income inequality (Patel, et al, 2018) or living in a conflict zone (Jayasuriya, Jayasuriya, Tay, & Silove, 2016). Specifically, proposing a simple behavioral intervention like the Tetris game to tackle intrusive memories in refugees from warzones like Syria (Holmes, et al, 2017) might deflect from the disabling and enduring consequences of war-related trauma (Silove, et al, 2014).…”