Social Determinants of Health and Health Disparities: Reading Reflection for Biological Mechanisms Lecture
Questions Related to Week 4 Readings:
1. Weaver et al propose that among rats, maternal behavior towards newborn pups influences their cortisol response to stress via epigenetic mechanisms that change the expression of glucocorticoid receptor gene for the rest of the pup’s life. They argue that because epigenetic patterns are established at specific developmental periods, there is extreme time sensitivity to when the pup is exposed to particular maternal behaviors (licking and grooming, in this case), and maternal behavior before or after that sensitive period window is not as important. Do you think this mechanism is relevant in humans? If so, what behaviors are most analogous to “maternal licking and grooming”?
I believe this mechanism is at least partially relevant in humans as studies have shown that environment and genetics interact to influence human development. Additionally, developmental plasticity has been shown in humans and mirrors the reversible effects of licking and grooming on the pups when cross fostered. That said, translating rodent data to humans can be very difficult and as a whole I feel caution must be taken when drawing conclusions from such studies. For example, humans possess an element of consciousness/ complex thinking that I believe allows us to overcome certain environmental and even genetic circumstances.
Behaviors that come to mind as most analogous to “maternal licking and grooming” are maternal infant skin contact directly after birth (skin-to-skin contact). Studies have shown that skin-to-skin contact influences oxytocin and cortisol levels in both newborns and parents directly after birth. An additional study following newborns and parents for 20 years exposed to skin-to-skin after birth showed long lasting social and behavioral effects.
2. Gruenewald, in contrast, emphasize the cumulative effects of SES adversity on a multi-system allostatic load measure. Do you think that the Gruenewald findings are consistent, inconsistent, or unrelated to the Weaver findings? Explain.
I believe, while there are some parallels, that as a whole the Gruenewald findings are inconsistent with the Weaver findings. Because the Weaver study showed higher AL as a function of greater SES adversity at each phase of, and cumulatively across, the life course. This finding suggests that there is not one “critical period” or point in development during which our response dictates life-long biological and behavioral responses, but instead that our experiences are additive and interact with each other to constantly revise our biological and behavioral responses.
3. 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?
This theory factors in the ability of genes and environment to, not only interact, but to amplify one another as well as acknowledges that “latent, pathway, and cumulative influences coexist”. I believe that the idea that GxE are interacting on multiple levels at once confers their ability to contribute greatly to major disparities along racial/ethnic, socioeconomic, or geographic dimensions.