Health Behavior vs the Stress of Low Socioeconomic Status and Health Outcomes

Since the late 1970s and early 1980s, a fundamental question surrounding the relationship between socioeconomic factors and health status has been: How much of socioeconomic differences and health can be attributed to socioeconomic differences in health behaviors? The article by Stringhini and colleagues¹ in this issue of JAMA represents an important contribution to understanding the social determinants of health by providing a better answer than previously available about this fundamental issue.

This question is important because even though the patterning of a wide variety of health outcomes by socioeconomic status has been demonstrated in numerous studies, well-established behavioral health risk factors, such as smoking, physical activity, dietary patterns, and alcohol consumption, also show a similar socioeconomic gradient. For the most part, after controlling for relevant health behaviors, there is still a significant amount of variation in health outcomes to be explained by socioeconomic factors.^{2 - 7} Moreover, socioeconomic inequalities in health are not reducible to health behaviors, although these inequalities are part of what creates them.

Based on repeated measurement of health behaviors in the Whitehall cohort of British civil servants, Stringhini et al¹ show that health behaviors explain a great deal more of class inequalities in mortality than observed in previous studies. Many who will dispute the study's findings have moved on from this debate long ago, having been satisfied that the investigation of the association of socioeconomic factors with health was an important area of inquiry even after taking into account behavioral factors. Efforts to dismiss socioeconomic inequalities in health as mere reflections of socioeconomic differences in health behaviors have been criticized as a politically safe interpretation that reinforces a status quo of significant and increasing social, economic, and health injustice within and between nations. Some proponents of health behavioral explanations for inequalities in health most likely will agree with the findings of this report. However, this study is important for the new issues it raises, some of which transcend this debate.

Perhaps most important, the study by Stringhini et al¹ does not suggest that socioeconomic differences in health are reducible to socioeconomic differences in unhealthy behaviors. Accordingly, it would be incorrect to infer that there is no need to be concerned with social and economic justice, only health behavior. There are several reasons for this important caveat, which raise other questions.

First, the study by Stringhini et al¹ is based on a relatively unique group of British adults, possibly becoming more unique as time passes. The Whitehall study has been conceptualized by some as a relatively narrow band of the overall socioeconomic spectrum in British society,⁸ and the repeated finding that lower-ranked civil servants experienced poorer health on a wide variety of outcomes was thought to indicate that it was possible to simply extrapolate the pattern at both ends of the gradient to individuals with lower or higher socioeconomic status outside of the civil service. By this logic, findings from the Whitehall cohort would be considered a reflection of British society at large. However, scientists involved in the Whitehall study have not encouraged this interpretation and have been careful to indicate that participants in the Whitehall cohort may be quite distinct.⁹

Second, the debate surrounding factors accounting for health status has been characterized as a simplistic matter of the stress of low socioeconomic status vs behavior as the explanation for socioeconomic inequalities in health.² With a broader conceptualization of stress, it is possible to consider both factors as part of the same pathway between relatively low socioeconomic status and health. Unhealthy behaviors are more common among individuals with low socioeconomic status because of the stress of low socioeconomic status.^{9 - 10} Accordingly, there is a direct causal pathway between low socioeconomic status and poor health as well as an indirect causal pathway through health behavior, which reinforce one another over the lifecourse.¹⁰ That is, the stress pathway is partly a behavioral pathway and unhealthy behaviors are coping mechanisms for the stress of low socioeconomic status. This observation does not dismiss the importance of behavioral risk factors nor suggest that reducing unhealthy behaviors would not be influential on population health. The problem is that traditional individually oriented health behavior education interventions are not very effective, and individuals with low socioeconomic status have been notoriously difficult to reach with such programs.¹¹

Third, the socioeconomic gradient both in health behaviors and stress responses to environmental stimuli like poverty also may be expressions of a person's development early in life. In child development research, 2 related concepts, self-regulation and executive function, represent the early life roots of capacities for stress management and health behavior. Self-regulation refers to processes that “enable an individual to guide his/her goal-directed activities over time and across changing circumstances,”¹² such as regulation or modulation of “thought, affect, behavior, or attention via deliberate or automated use of specific mechanisms and supportive meta-skills.”¹² Similarly, executive function consists of “the skills involved in organization, planning, deliberate intention and self-monitoring, self-control, and working memory to repeat trial behavior.”¹³ Self-regulation and executive function are important processes governing health behavior, and pilot data have reinforced this view.¹³ However, problems of self-regulation and executive function are patterned by socioeconomic status, with children of lower socioeconomic status more likely to have deficits in these processes,¹⁴ suggesting that experiences of the stress of low socioeconomic status and unhealthy behaviors have common roots early in life and should be considered part of the same adult pathway.

The inference that should be drawn from the study by Stringhini et al¹ is that both health behaviors and social and economic determinants of health remain important factors. Moreover, the stress of low relative socioeconomic status vs health behaviors argument should be considered obsolete. Socioeconomic differences exist for almost every major contemporary and historical cause of morbidity and mortality, suggesting the presence of a common pathway. Moreover, plausible evidence suggests that those pathways are traceable to the development of self-regulation and executive function early in life. This concept represents a modernized version of the notion of “host resistance” and now includes early life developmental phenomena. The study by Stringhini and colleagues¹ is not the end of the debate and inquiry involving the relative influence of behavior and socioeconomic factors on health status, but rather may well represent the beginning of a new model for investigation.