1. Hertzmann and Boyce argue that “it is not genes or environment, nor is it genes and environment, but rather it is gene-by-environment interactions that influence developmental trajectories.” To what extent do you think that GxE interactions can contribute to major disparities along racial/ethnic, socioeconomic, or geographic dimensions? Please consider this both in general and in respect to your particular area of interest.
I think GxE interactions are undervalued in how much they can contribute to major disparities. Hertzmann and Boyce list many ways (HPA axis, autonomic nervous system, development of prefrontal cortex, etc.) in which our environment can become biologically embedded in an individual. However, aside from noting in the mouse licking study that nurturing behavior is passed on to other generations, they do not explore more deeply the ways these biological embeddings are transmitted to future generations in humans. Biological consequences of environmental stressors can be passed on to the next generation, who then bear the consequences of these embeddings and are subsequently predisposed to more prejudices, which then cause even further biological embeddings. Thus, a vicious cycle begins where biological consequences and societal prejudices can compound with every generation. These disparities can form and solidify along racial, socioeconomic, and geographic dimensions depending on when and how the initial environmental stressor took root. In head and neck cancer, where tobacco and alcohol are major risk factors, one can see how chronic stress levels (secondary to systemic racism and resulting socioeconomic disparities) and cultural views on smoking (based on geography) can increase one’s predisposition to taking up tobacco and alcohol. These behaviors are then embedded in the individual’s biology and increases risk of head and neck cancer.
2. Discuss implications of epigenetic mechanisms of disease for intergenerational effects on health disparities, as well as for interventions designed to address health disparities.
As discussed in question 1, epigenetic changes can be compounded with each subsequent generation. For instance, in the hypothesized transgenerational flow of chronic disease, the environment in which a grandmother was raised can have biological implications on her grandchild’s oocytes. If the grandmother suffered from poor nutrition due to systemic racism, her subsequent offspring could be at higher risk for chronic diseases/cancers and also be subjected to systemic racism. Now the grandchild bears “double penalty” – poor health secondary to her grandmother’s environment and current environmental stressors. However, identifying these epigenetic mechanisms can allow for interventions specifically designed to stop this domino effect. For example, it is known that infants of mothers who smoke have low birthweight; health interventions targeted towards populations with higher smoking rates can be designed to curtail this disparity.
3. Discuss how the findings in the Robinette paper relate to socioecological model we are using in this course – e.g. briefly describe how the different levels displayed in this model are related to each other in this paper.
In the socioecological model we are using in class, economic & social opportunities/resources shape our living/working environments, which then affect an individual’s behavior and medical care. In the Robinette paper, the authors mainly investigated how an individual’s neighborhood (i.e., living/working environments) affected an individual’s health, assessed via 24 physiological indices. Several measures the authors took that related to living/working environments include neighborhood cohesion, neighborhood safety, and neighborhood income while behavior and medical care were assessed through measures of exercise regularity, smoking, fast food consumption, and physiological indices. The authors conclude that living in low SES neighborhoods confer chronic stress on its residents, which then manifest as worse anxiety and health behaviors, demonstrating the strong relation between living/working environments and behavior & medical care.