Several researchers have observed health effects of income/wealth even after adjusting for many other relevant factors (33, 58, 62). Particularly when other socioeconomic factors are inadequately measured, however, observed associations between income/wealth and health may reflect effects of other socioeconomically linked factors such as educational attainment and quality, childhood socioeconomic circumstances, neighborhood characteristics, physical and psychosocial working conditions, and subjective social status. The health effects of low economic resources may be ameliorated by access to other resources and opportunities; for example, some relatively low-income countries/states (e.g., Cuba, Costa Rica, and Kerala, India) have favorable health indicators that may be explained by long-standing societal investments in education, social safety nets, and/or prevention-oriented medical care (41). Income inequality (measured at an aggregate
level) has often been linked with health (116), although a causal link is debated (65, 116). Income inequality could affect health by eroding social cohesion (59). The link could also be explained by other factors strongly associated with both income inequality and health, such as lack of social solidarity, which could be both a cause and an effect of income inequality.