http://bmj.bmjjournals.com/cgi/reprint/321/7272/1311.pdf

"... The joint effect of income inequality and household income on health has received limited attention. On p 1311 Kahn et al focus on symptoms of depression and self reported health among a large sample of US mothers with young children. They found a strong gradient of household income: women in the lowest fifth of household income were more likely to report depressive symptoms than women in the highest fifth (33% v 9%). High income inequality also significantly increased the risk of poor health but only for the poorest fifth of women: these women in states with high income inequality had a higher risk of depressive symptoms (odds ratio 1.6) than the poorest fifth of women in states with low income inequality. Clarifying such interactions may help to focus research on the specific mechanisms through which income inequality operates...."