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 would suspect that gene-environment interactions could be implicated as contributing to the majority of health disparities. I am not in genetics but from what have seen, most genetic risks for major health problems (cardiovascular disease, cancer) are a combination of multiple factors; there is rarely a single-gene that is sufficient cause for disease (though we can think of lots of single-gene diseases their prevalence and societal burden are far less than cardiovascular disease/cancer, multifactorial diseases with environmental contributions). The example of antisocial behavior demonstrates the interaction concept as environment "unlocking" a disease that's only possible with a particular genetic variant (a variant which would not cause disease without the environmental factors). Thinking more broadly about the concept of interaction, an example of gene#environment interaction is genetically-determined skin color and racism. One is hard-pressed to biologically link skin color to most health problems but in the presence of historical and ongoing structural racism, we see major disparities, for example in the incidence of kidney failure and dialysis (which itself is most often an end product of hypertension and diabetes - which themselves may have some genetic risk factors but for which the lifetime impact is more reflective of environmental factors such as access to care, glycemic/BP control over the years, etc).
2. Discuss implications of epigenetic mechanisms of disease for intergenerational effects on health disparities, as well as for interventions designed to address health disparities.
It seems like epigenetic mechanisms are somewhat akin to genetic factors (in that there is evidence of cross-generational transmission) except that are potentially modifiable. This has a number of implications. First, if previous generations experienced differential maladaptive changes in racial/ethnic, socioeconomic, or geographic dimensions, is important to recognize that some of this inter-generational "memory" can have lasting health impact today, and add to the health risk of particular minority groups on top of the effects of ongoing racism/classism, structural or otherwise. Also, it suggests that when assessing the impact of interventions to address health disparities, we may not see the full effect until if/when epigenetic factors are reversed; furthermore, it suggests that equalizing care by any/all measures may NOT in fact yield equal outcomes, even if there are no relevant genetic differences, if epigenetic factors are at play.
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.
Robinette et al use allostatic load (which represents a composite of physiological factors posited to, with higher load over time, represent a risk for future health problems) as a measure to link to neighborhood income. For example, neighborhood-level lack of safety and low social cohesion are living conditions that lead to a constant state of heightened vigilance that can contribute to chronically elevated psychosocial stress and higher allostatic load. The authors looked at behaviors (fast food consumption, smoking, exercise) which contribute to allostatic load. The authors examined the association between neighborhood income and allostatic load, finding that there was an association even after adjustment for safety/cohesion/perceived stress factors, behavioral factors as well as adjustment for individual income (to help isolate neighborhood income effects). This relates to our Braveman socioecological model since the hypothesis and analysis were informed by an attempt to examine what kinds of factors (psychological, affective, behavioral) could account for the association between allostatic load and neighborhood income, which reflects living/working conditions and behavioral components of the framework.