Poverty, Material Hardship and Depression.

Mental health disorders are of great social, economic, and policy concern. Mental health is defined according to the Surgeon General as “a state of successful performance of mental function, resulting in productive activities, fulfilling relationships with other people, and the ability to adapt to change and to cope with adversity” (U.S. Department of Health and Human Services, 1999: vii). Furthermore, mental health is required for an individual to maintain social relationships with others and contribute to society. At the individual level, the general association between health and income is well established and has been found in different places, time periods, genders, and ages (Lynch et al., 2004; Adams et al., 2003). In terms of mental health disorders, Kessler et al (1994) report a higher lifetime and 12-month incidence of depressive, anxiety, and substance use disorders among low-income individuals. More recently, Kessler et al. (2003) report a higher 12-month incidence of major depressive disorder among those living in or near poverty. Adults with serious psychological distress were more likely to have less than a high school degree (34%) than those without serious psychological distress (17%). Additionally, adults with serious psychological distress were more likely to have family income below $20,000 (44%) than those without (20%) (Pratt, Dey and Cohen, 2007). The relationship between income and mental health is not just found at the very bottom of the income distribution or for those living below the federal poverty line. There is a clear income gradient to health such that every step above the poverty line is associated with an incremental improvement in health (Lynch et al., 2004; Ecob and Davey Smith, 1999). While it is clear that depression results in lost income (Marcotte and Wilcox-Gok, 2001; Kessler et al., 2006; Greenberg et al., 2003), there is a growing consensus that socioeconomic disadvantage precedes poor mental health. Although reverse causation—poor mental health leading to lower earnings—is present, it is no longer considered the primary mechanism behind the association between income and health (Lynch et al., 2004). Several longitudinal studies have specifically examined the relationship between depression and socioeconomic status and concluded that the causal direction runs from socioeconomic status to depression (Risher et al. 2001; Muntaner, et al. 2004; Miech et al. 1999; Johnson et al. 1999). Thus, exploring new dimensions along which the income-mental health gradient may operate is of substantial interest. At the present time, most recent research on mental health outcomes continues to include either a measure of poverty, income or socioeconomic status in the models (Perreira et al. 2005; Hawkins and Booth 2005; Turner et al. 2004; Serido et al. 2004; Evenson and Simon 2005). There is no research explicitly examining how material hardship mediates the effect of poverty on mental health. Moreover, the relatively few studies that looked at the broader association between hardship and mental health suffer from two limitations (Heflin et al. 2005; Laraia et al, 2006; Casey et al 2004). First, they tended to focus on only one type of hardship. In this project we expand the scope to include five dimensions of hardship. Looking at multiple forms of hardship allows us to determine if some forms are associated more closely with depression than others. Second, previous work relied upon cross-sectional data or data from community-based studies. We use longitudinal data collected in the Fragile Families Survey– a survey of births in cities with populations greater than 200,000 in 1999 in the United States. This allows us to conduct more precise causal modeling, via conditional logistic fixed-effect models, that explicitly incorporate time-invariant unmeasured heterogeneity into our model. The data also provide insight on a population (households with new births) vulnerable to poverty and hardship, and which have been the focus of policy interventions in recent years, such as through welfare reform initiatives. Finally, we contribute to literature in social epidemiology by providing a direct test of the extent to which the relationship between income and depression is mediated by material conditions.