Epidemiology 222
Health Disparities
HW 3 -Week 4
Curt Johanson (added course 2/2/2019)
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”?
This is most similar to human mothers nursing their child while holding them in front of their body or in a sling. Human mothers also groom and bath their children as well and clean and feed them. The other really fascinating part of this study is that even when they “cross-fostered” the rats and switched them shortly after the gene expression, the baby rats switched back and gene expressed to match the surrogate mom. Rats who were born from mothers who lacked licking & grooming (LG) and arched back nursing (ABN) genetic profile soon adopted the same gene expression pattern of the new mom. Conversely the rats born from the loving mom lost all the benefits from the affectionate mom gene expression when they were switched. This is very important for humans if it follows a similar physiological manifestation as children in severe adverse environments often develop extremely adverse personality traits. It is good to know that kids can be adopted and raised by non-biological parents and turn out all right as long as they have loving and attentive people raising them during critical periods.
2. Gruenewald, in contrast, emphasized 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.
They do not really have anything to do with the other findings by Weaver as one is the biology driving gene expression in early life causing immediate changes. The weaver article shows genes being turned on and off by early childhood changes during a “critical period” while the other study showed how low SES and life course significant traumas can build up over youth and adulthood chronically effecting health.
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.”
Most of what people think are huge biological differences between race are very subjective and based on very superficial differences like hair or eye color To what extent do you think that GxE interactions can contribute to major disparities along race leading to manifestations of disease can be almost completely overshadowed by the much larger effect size of race itself and other SES measures. It doesn’t look like G&E really separate the so called “races” nearly as much as individual effects of gene on environment on the personal level. The one very promising finding about this article is that those who had childhood low SES and poverty but were upwardly mobile and changed to high SES in adulthood had Allostatic load values that were almost identical to the permanent full time high SES group that never changed. This could lead to possible biological or epigenetic interventions that could lift someone out of a lifetime of being stuck with hardship if we can discover what was most helpful to avoid as they rose out of the allostatic swamp.