1. Write a paragraph describing the extent to which an socioecological framework incorporating issues related to social determinants has been applied to your area of research. Are there opportunities for improving our understanding of or approach to disparities in your area with a greater emphasis on a socioecological framework?
One of my focuses is non-alcoholic fatty liver disease among adults experiencing food insecurity. A bulk of literature applies the socioecologic framework to associated cardiometabolic risk factors (diabetes, obesity, hypertension), but few to non-alcoholic fatty liver disease in of itself. Lazo et al 2015 offers perhaps the best framework when exploring NAFLD disparity among persons of Hispanic origin, broken down by ‘upstream’ (governmental regulations, occupation, urbanicity), ‘midlevel’ (education, social norms, environment, community resources) and ‘individual’ (dietary pattern, physical activity, healthcare access and health-related beliefs, substance use). Broadly, from a societal perspective, numerous studies have raised the potential connection between food policy (cost, quality and access), exploring the association between high-fructose diet (Hoorst et al 2017) and nutrition/food quality (Leslie et al 2014) with NAFLD prevalence. From the physical environment, Diehl et al 2015 suggests environment through sleep-wake disruptions (work shifts and migration) can alter lipid metabolism, visceral adiposity and NAFLD. On an individual level, cardiometabolic disease control through behavior is thought to modify NAFLD onset and progression risk (Lonardo et al 2017). I think the greatest opportunity for improving a socioecological framework approach in this field would be both to incorporate existing models for shared risk factors (diabetes, hypertension and obesity) as they apply to NAFLD and add a varying function over life course and disease stage for potential disparities in advanced fibrosis.
2. In the WHO reading, A conceptual framework for action on the structural determinants of health, the authors describe structural stratifiers (e.g. income, education, etc) and intermediary determinants such as material and psychosocial circumstances. Pick 3 of these factors (at least one structural and one intermediary). Explain why you chose the factors (might use Braveman article to provide justification) and describe how each could be an important determinant of a health outcome of your choosing. The association could be reported in published research or it could be your hypothesized relationship. Consider whether how these factors might function over the lifecourse and/or intergenerationally.
In the CSDH framework, the structural stratifiers (income, education, occupation, social class, gender, race/ethnicity) and intermediary determinants (material circumstances, psychosocial circumstances, behavioral and/or biological factors and health system itself) are described to shape health outcomes. I will discuss income, psychosocial circumstances and behavioral with food insecurity and non-alcoholic liver disease.
Income- As described in the reading, “…household income may be a useful indicator, since the benefits of many elements of consumption and asset accumulation are shared…”. Further, Galobardes et al postulates a mechanism through buying access to better quality food, access to health services and health selection as income level (‘reverse causality”). Income disparities may limit access to food quantity (disruption) and quality, where numerous studies explore diet composition, gut microbial translocation and inflammation to NAFLD disease progression. (Machado et al 2016, Federico et al 2016, Kirpich et al 2015). Emerging evidence supports a bidirectional relationship between NAFLD and cardiometabolic risk factors (diabetes, hypertension; Lonardo et al 2017), where comprised access to healthcare both increase onset and control of these chronic disease risk factors. Finally, the dose dependent response seen with food insecurity and other chronic cardio-metabolic diseases prevalence and poorer outcomes (Gregory et al 2017, Berkowtiz et al 2017) that overlap with NAFLD may be a result of reverse causality, where those with more severe illness limits individual’s earnings and resources. These factors would change through life course and may have varying impact to NAFLD disease progression depending on both disease course and coexisting risk factors.
Social environment or psychosocial circumstances- Per the reading, this includes “psychosocial stressors” and varying exposure and experiences as perceived stress. Insulin resistance may be an evolutionary protective adaptation to conserve muscle mass during hunger, which may be exacerbated by present day food disruption (Seligman et al 2010). Hyperinsulemia can then induce fat breakdown, increasing free fatty acids that are taken up by hepatocytes and promote lipotoxicity and inflammation (Diehl et al 2017, Petta et al 2016). Anxiety around food procurement may induce cortisol, increase systemic inflammation and promote central obesity and insulin resistance (Gowda et al 2012). Dysregulation of adrenergic signaling seems to occur in human nonalcoholic steatohepatitis. As described above, this would alter through a life course and depend on stage of disease progression and coexisting risk factors. Additionally, this is also likely a function intergenerationally, where maternal stress has been shown to increase risk of insulin resistance and obesity in children, predisposing to NAFLD risk as described above.
Behavioral – This is described as “inequalities in health associated with social differences in lifestyle or behavior…found in nutrition, physical activity and tobacco and alcohol consumption”. Differences in lifestyle may account for some variation in NALFD, particularly in mechanism of material factors as a source of psychosocial stress influencing health-related behaviors, such as diet rich in saturated fat and/or energy-dense, leading to inflammation, etc (as described above). Disproportionate substance use, particularly alcohol and/or IVDU (and viral hepatitis acquisition) would increase NAFLD disease progression among marginalized and function potentially intergenerationally (ie vertical transmission). Limited resources influencing behavior would also function over life course, with more dependables/obligations increasing competing demands that may impact mental health, force trade-offs with needs (ie food) and medical care and distract for chronic care self-management (Seligman et al 2010), further predisposing to NAFLD onset and progression.