Do Chronic Stressors Impact the Association Between Substance Use and Well-Being: Findings from the Midlife in the United States Study.

Background: Substance use is a global public health concern. However, how psychological stressors, such as job discrimination, mediate the association between substance use and holistic well-being is still unclear. Methods: Data were merged from the main and the biomarker projects of waves 2 to 3 of the Midlife in the United States (MIDUS) study. Using structural equation models, we examined whether participants' (N = 1,729; Mage = 62 ± 10) substance use, assessed by the usage of 10 different non-prescription medications, predicts better holistic well-being, assessed by a composite flourishing score, including emotional, psychological, and social well-being, over time while controlling baseline flourishing and other covariates (sociodemographic, health, and functional status). We also examined whether individuals' psychological stressors, assessed by a composite score of multiple aspects of discrimination, mediate the above association. Results: Findings revealed that individuals' substance use has a negative and significant effect (b = -0.854; SE = 0.227; p < .001) on composite flourishing. Further, psychological stressors have a negative and significant association (b = -0.177; SE = 0.066; p = .008) with composite flourishing, and it also mediates the above association. Conclusions: The current study extends earlier research showing the impact of substance use on individuals' well-being. Future research should examine biomedical mechanisms for potential aspects of substance use and psychological stressors on late-life holistic well-being.