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.
In general, it makes sense that genes and environment interact together. Gene
expression and regulation does not happen in a vacuum, but rather occurs in
response to specific inputs. Even single celled organisms can sense a change in
environment and produce a change in their genomic expression in response. In my
area of interest, dementia, there are many genetic mutations that are
associated with the onset of dementia, but do not always cause dementia. Certainly,
there are factors that are spread across the life course of an individual that
can result in variations in the onset time and duration of dementia. For
example, higher education is associated with later onset of dementia. This is
thought, in part, to be a result of “cognitive reserve” where the aging brain is able to
continue functioning longer due to increased connectivity and plasticity among
neurons. Examining education in the life course perspective, individuals who
are born into families or communities that don’t value education, or who live
in neighborhoods with less access to education will be less likely to attain
higher levels of education. Less education or delayed education can have
critical effects in the development of a child. Executive functions in the
prefrontal cortex regarding social and emotional intelligence develop from ages
three to nine, and a lack of education in this timeframe may have long lasting
effects on the ability for children to attain education later, which can in
turn have compounding effects on an individual’s allostatic load as time goes
on. This may limit the types of careers than an individual can have, perhaps
leading to a job that requires long hours or labor. This may affect the amount
of sleep that an individual gets, or the diet an individual has, which can all lead
to changes in the risk for dementia. One thing that I have kept in mind,
however, is the idea of the “healthy survivor effect.” This refers to the idea
that individuals who reach old age, >80, tend to have health and dementia outcomes
that are closer to one another across racial/ethnic, socioeconomic, or geographic
categories. Since dementia is typically something that is rather late in its
onset (at least for sporadic/non-familial cases), it may require a different
approach to pinpoint the exact social determinants of health that lead to dementia,
because there are probably things about the people who survived that are
different than people who would have gotten dementia but had a mortality due to
some other cause before it happened.
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’s possible that a troublesome and perpetuating cycle of issues may be established among families and communities that are faced with health disparities. One of the papers talked about the idea that a child developing in the uterus of a mother with a nutrient poor diet may develop a metabolism that is designed to conserve food and energy and seek high-calorie food. This can lead to obesity and may not promote the ability to get a good diet for oneself, which may lead to the next child having similar issues. The paper also described the case of the mouse that was handled less, but then introduced to a parent that handled it more, and the outcome was positive. Altogether, this suggests that interventions for health disparities may be appropriately targeted at the community or population level rather than only at the individual level. In this way, the therapeutic effects may span multiple generations, which is necessary to address some health conditions.
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’s paper examined neighborhoods as an economic and social opportunity to address health disparities. The paper examined neighborhood safety, income, and cohesion and its effects on allostatic load, affective distress, health behaviors, and SES of individuals. The main findings suggested that neighborhood income is major factor that causes allosteric load, and this effect is mediated by factors like an individual's perceived stress, safety, anxiety, and health behaviors.
In our course, we note that in the socioecological model, economic and social opportunities and resources, living and working conditions of homes and communities, and individuals health behaviors and access to medical care can all interact with one’s biology down to the genetic level to result in varied health outcomes. The Robinette paper reflects this socioeconomic model, demonstrating, for example, that an individual living in a low income neighborhood is more likely to feel stress and a lack of cohesion, which establishes a chronic state of excitement that can damage the body over time through poor health behaviors. Each level of the model effects the other. It is important to consider the interplay between each level of the model if the health of an individual is to be properly addressed.