Income and Mental Well-Being of Middle-Aged and Older Americans: Immigrants' Diminished Returns.

Introduction: Although income is among the major social determinants of mental health of middle-aged and older individuals, socially marginalized groups gain less health from their income and other socioeconomic status (SES) resources compared to socially privileged groups. This pattern is called marginalization-related diminished returns (MDRs). Most of the existing knowledge on MDRs, however, has been derived from studies that have defined marginalization based on race, ethnicity, or sexual orientation. As a result, very limited information exists on whether similar MDRs can be observed for middle-aged and older immigrants or not. Building on the MDRs framework, this study compared a national sample of immigrants and non-immigrants for the effects of income on the mental well-being of middle-aged and older adults in the United States.

Methods: This is a cross-sectional study. The 2015 National Health Interview Survey (NHIS) enrolled 14 149 middle-aged and older individuals who were either immigrants (n=1977; 14.0%) or non-immigrants (n=12 166; 86.0%). The independent variable (IV) was income that was treated as a continuous variable. The dependent variable was mental well-being, also treated as a continuous variable. Age, gender, race, ethnicity, education, marital status, employment, self-rated health, obesity, and region were confounders. Immigration (nativity status) was the moderator. Logistic regression was applied for data analysis.

Results: High income was associated with higher odds of good mental well-being in middle-aged and older adults. However, immigration showed a significant statistical interaction with income, which was suggestive of a smaller protective effect of high income on mental well-being for immigrant than non-immigrant middle-aged and older adults.

Conclusion: In line with MDRs, the association between income and mental well-being is weaker for immigrant than non-immigrant middle-aged and older adults. There is a need to help high income immigrants secure health outcomes similar to those of non-immigrants. Such changes may require bold and innovative economic, public, and social policies that help immigrants more effectively translate their income and socioeconomic resources into tangible outcomes such as mental well-being.