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 appreciate that Hertzman and Boyce specify that it is gene-by-environment interactions that influence development, not genes and/or environment alone, because laypeople such as journalists may easily misinterpret research studies in this area as providing scientific evidence that people of certain races have superior attributes, such as being more "intelligent." I am reminded of the press surrounding a controversial book published in 1994 entitled The Bell Curve in which the authors were reported to have argued that that racial differences in IQ were based only in genetics. The authors responded by pointing out that they actually wrote in their book that "both genes and the environment have something to do with racial differences." However, Hertzman and Boyce take this a step further by detailing examples of and the scientific mechanism by which gene-by-environment interactions influence early childhood development. Mendoza et al.'s study showed how these interactions (namely DNA methylation and racial discrimination) were apparent for mostly 30 to 39 year old women, and Robinette et al. showed how such interactions (namely allosteric load and neighborhood income) applied to people in mostly from 34 to 84 years old. These studies show GxE interactions are likely to play huge roles in health disparities along multiple dimensions, and more research should be focused on elucidating more of these interactions. In my research area of interest (radiology), it would be interesting to examine how GxE interactions may influence habits such as following-up after abnormal mammogram, or how GxE interactions may influence patients' responses to interventions (e.g. whether they experience adverse effects) such as radiofrequency ablation or angioplasty.
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 I pointed out above, each of the required readings this week demonstrated how epigenetic mechanisms of disease can result in health disparities during all phases of life, from birth to old age. What is particularly alarming is how these GxE interactions may result in permanent biological changes in the individual once the interaction has occurred, depending on the severity of the circumstances. For example, Hertzman and Boyce pointed out that Romanian children orphaned later in life were found to have more easily reversible developmental disturbances. Studies such as these may make a case for more aggressive early childhood interventions (e.g. expand Head Start preschools, improve the quality of elementary schools in low-income neighborhoods, including providing more mental health resources in such schools) to address adverse GxE interactions so that vulnerable children can be "reached" before the epigenetic changes are permanent and will follow through throughout the rest of their lives and potentially passed on to their offspring.
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.
The Robinette paper showed that there is a significant association between higher neighborhood income and lower allosteric load after adjusting for individual income, age, and gender. The authors also found that part of the allosteric load findings could be accounted for by other factors such as anxious arousal symptoms and lifestyle habits such as fast food consumption, tobacco use, and exercise. These findings seem quite consistent with the socioecological model we are using in this course: I am thinking of the RWJ Foundation Framework for how the various levels of social factors--social and economic resources, living and working conditions, and behaviors and medical care--each have an interaction(s) with patients' genetics. One of the most interesting findings in the Robinette paper that shed nuanced light on such interactions was how allosteric load was found to be significantly higher among those living in neighborhoods that they perceived to be unsafe (such as in "ethnic ghettos") as compared to those living in neighborhoods perceived to be safe (such as in "ethnic enclaves"), even after adjusting for other factors related to neighborhood socioeconomic status. This finding suggests that there chronic fear regarding one's neighborhood may cause psychological damage that negatively influences one's allosteric load (the authors note that more research would be needed to provide evidence of this).