Health Disparities Forum

Questions Related to Week 5 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 tentatively say that this behavior is relevant in humans.  However, there are other hormonal pathways that the authors either don’t examine, or are more complex in humans.  For instance, oxytocin is implicated in breastfeeding, accelerating uterine involution, and also maternal bonding.  This bonding is interrupted in many ways relevant to my own work, and also potentially relevant for health disparities.  Many women around the world who give birth in hospitals are unnecessarily separated from their newborns after normal deliveries; some hospitals have begun a push to respect “the golden hour” immediately following delivery.  The golden hour seems roughly to be based on important developmental windows for the mother and newborn. 

However, I am cautious at the same time about biological explanations of “maternal” behavior, because what counts as “maternal” changes greatly over time and place, and these definitions have sometimes been closely connected to race.  In the 19^th century, many obstetricians believed that white women had more fragile constitutions, and that the pain that they experienced during labor—while essential for “maternal bonding”, was also a sign of their higher evolutionary status.  To the contrary, under slavery, it was believed that slave women had painless births; the “fact” that slave women did not suffer pain with their labors meant that they did not bond with their children.  This in turn justified selling enslaved children off to white owners.   There are parallels to be drawn to the way the “crack baby controversy” played on in the 80s, which served to once again mark Black motherhood as deviant and responsible for a whole host of social ills. 

One of the readings from the first week discussed how research that demonstrates racial disparities, can in turn reinforce the ongoing significance of race.  How can we account for the ways that race/SES/mothering powerfully affect bio-social trajectories, without also reinforcing those same categories that have used biology as a basis for discrimination? 

1. Provide a brief proposal for a study that would allow you to assess whether epigenetic modifications in humans in response to maternal behavior influence subsequent health of the human (feel free to choose any health or behavioral outcome you think you can do this with, e.g., dementia or depression or smoking). Bonus if you can explain how you would approach this if we assume that the relevant epigenetic changes are tissue specific and occur in the brain. 

I would try to find a site where we could take advantage of natural variations in hospital practices.  For instance, compare two hospitals where it is routine practice to immediately separate the mother and the newborn, and one where this is not routine practice.  Ideally, these two hospitals would be in the same country and have a range of SES in their populations. Outcomes would include those collected in the hospital (breastfeeding and bonding measures), at home (sleep quality, maternal mood, bonding measures), clinical outcomes for the baby (weight gain, developmental milestones), and also functional MRI studies at different periods of the baby’s life (we can’t dissect the baby brains to explore tissue specific epigenetic changes). 

1. 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 think the allostatic load model incorporates the Weaver article in that the Weaver article deals with only one of the allostaic load measures (HPA axis).  I believe the Grunewald article more accurately models the complexity of human physiology and life course events, rather than a strict perinatal/newborn environment perspective that (cynically?) argues that life-trajectories are fixed from the start.  However, there is a tension between the biological windows of human development and the accumulation model of Gruenewald.  It seems plausible that inequalities in pregnancy and the perinatal to under five period may indeed have an outsized impact on life trajectories. 

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?

To be honest, I was a confused by the distinction they were trying to make with the term “gene-by-environment”.  It absolutely makes sense that humans have windows of development that correspond to certain functions/abilities, and that these functions are based in both genotype and phenotype (example: fluency in multiple language in early childhood).  At the same time, we know that humans are capable of flexible adaptation (example: migration to a new country in adulthood).  Of course, we are not totally plastic “tabula rasa” throughout our life.  Opportunities for development will close themselves off, and these developmental opportunities are not distributed equally.  If the under 5 developmental period is so important, what kinds of interventions could ethically respond to this issue?  Should the state have a role in regulating family interactions under the age of five?  This makes me worried about what kinds of interventions (and intrusiveness) into family life of poor people’s children.  The opposite of this is that we don’t give thought into interventions that would reduce the wealth and privilege of the powerful (we talk a lot about poverty alleviation but not wealth reduction).  Poverty is not produced in isolation, so we need to consider exactly how wealth is tied to better developmental outcomes; because the level of wealth disparity is not sustainable, we need to consider wealth reduction policies that would not necessarily harm developmental outcomes.