Researchers have long observed that children growing up in poverty are at greater risk for cognitive and psychological delays. These early difficulties continue to hinder normal growth throughout childhood and into adulthood, potentially leading to lower academic achievement and perpetuating disadvantage into subsequent generations.
To understand the deep physiological basis for poverty and brain development, researchers have turned to the burgeoning field of brain imaging.
A recent study appearing in the online journal PLOS One uses data from a multi-site brain imaging study to compare the amount of gray matter in the hippocampus of poor and non-poor children. The hippocampus is the region of the brain associated learning and memory that is known to be affected by stress. Growing up in an impoverished environment might produce enough of the stressors to disrupt the normal development of the hippocampus. In animal studies, low levels of stress and the availability of enriching environments have been found to promote the development of the hippocampus and to increase resiliency by increasing neuronal cells.
The authors classify income into nine categories, and find that a one point increase in the income score is associated with an overall increase of .14 standard deviations in the concentration of beneficial gray matter in the hippocampus (results are similar looking at total hippocampus, and the left and right hemispheres separately). The authors find no association between income and whole-brain volume, however. Because the study screened out children with severe developmental delays and mental health conditions these results likely understate the overall impact of poverty on hippocampus development.
A Policy for Better Brains?
Much has been made of the importance of intervention targeting the brains of very young children, including the landmark National Academies report “From Neurons to Neighborhoods,” and if the hippocampus is implicated in this early development than the study further strengthens the case for improving the quality of day care and early parenting. Yet it remains unclear how to measure all of the inputs to brain development, including income, which is surely more a proxy than a direct cause of brain development. Policymakers are still searching for the optimal mix of inputs to promote brain development in children, and perhaps just as importantly, to sustain that development over the life course.
There is also some danger in making too big of a deal of the differences in the brains of poor and non-poor people, even if the intention is to highlight the damaging role of deprived environments. Research such as this study highlights a tension among scholars that study the psychological basis of poverty between showing that the poor possess the same mental capacities and emotional resources as the non-poor but operate under more constraints that predictably cause them to make bad decisions, and those that emphasize the underlying cognitive and emotional stresses that eventually “get under the skin.” For better or worse, we lack a discourse that can make a clear moral and conceptual distinction between the distressed environment and the brain that is caused by it.
Inequalities 
4 responses to “This is Your Brain on Poverty”
As someone who’s done quite a bit of work in neuroethics (I have studied pain for a long time now) and is working on the SDOH, this kind of work sits right at the nexus of my research agenda. I think it’s fascinating to be able to demonstrate via neuroimaging the neuropathological effects of deleterious social and economic conditions in early childhood.
However, as I remarked in a recent RWJF webinar that highlighted this work, one has to be extremely careful of the reductionism typically engendered by the neuromolecular gaze. That is to say, we do not really require neuroimaging to have mountains of data on the devastating health effects of deleterious SDOH in early childhood. Neuroimaging is an immensely powerful form of visual rhetoric, but substantively, it does not really provide more epidemiologic information per se, but rather provides a powerful way of viewing the mechanisms by which deleterious SDOH impact cognitive development and ultimately health across the lifespan.
The real problem is that both historical and contemporary analyses of neuroscience and neuroimaging show without question the all-too-common tendency to reduce complex social phenomena to individual brains. This trope is not only fallacious in its own right insofar as it deflects attention away from the kinds of collective actions and social policies needed to ameliorate deleterious SD, but has also had demonstrably horrific effects on some of the more vulnerable and stigmatized subgroups in American society (e.g., the mentally ill, women, etc.). One should also be mindful of the links adduced between neuroreductionism, degeneracy, and crime in context of American eugenics policies and practices.
What it comes down to for me is the policy impact of this kind of work, which to me is minimal unless one seeks specifically to harness the rhetorical power of neuroimaging. We already know the effects of deleterious SD in early childhood on both cognitive development and on health over the lifespan. We already know what kinds of policies and interventions are most likely to improve population health and compress health inequities. I generally do not see how what neuroethics and social neuro scholars have often termed “pretty pictures of brains” really add much or change our views regarding policy responses. And inasmuch as they run the risk of supporting yet another technocratic, health care-oriented, magic-bullet medical solution to social problems, they may actually do harm.
Daniel,
It’s a great pleasure to hear your perspective on this, as you have clearly thought about this a great deal. In my post when I said: “There is also some danger in making too big of a deal of the differences in the brains of poor and non-poor people, even if the intention is to highlight the damaging role of deprived environments,” I was trying to highlight some of the same concerns that you raise, and I agree with you that the results of neuorscience often become crudely reductive when they are appropriated by social scientists (let alone policymakers). So I join your skepticism, and worry about the stigmatizing effects of these studies, or at least the stigmatizing conclusions that some people might reach.
I do want to push back, however, on the assertion that: “We already know what kinds of policies and interventions are most likely to improve population health and compress health inequities.” There’s a lot we still don’t know about the causal effects of income on health, let alone the mechanisms that mediate income to health, and even less is known about whether different types of policies or investments will promote health (get a room together of social epidemiologists, health economists, and policymakers and ask them whether we should promote health by giving families big cash payments or by providing more services to their children… you won’t get anything close to a consensus). We also don’t know whether some effects are continuous (more is always better) or are discrete. Studies like this one, that link a biological marker with variation in the population, can help us to get a better handle on these questions. That seems worthwhile, even if social scientists are still behind on finding the right moral and rhetorical framework.
Hey Brendan,
Thanks for the kind words. I am moving away from overt work in neuroethics — my comments here hint at why — but I have indeed spent some time thinking about these matters.
You’re absolutely right to push back against the overstatement in my quoted claim. But note that the fact that there is an awful lot we don’t know is entirely compatible with the claims that (1) there is an awful lot we do know, and that (2) what we do know is sufficient to justify a host of public policy responses. I’d also add that we are not simply talking about the income-health relationship here, which is certainly highly contested on a number of different levels.
Rather, we are talking about the connections between deleterious SD in early childhood and its health effects across the lifespan. This matters because my reading is that if there is one component of the social epidemiology that enjoys remarkably robust evidence and unusually widespread agreement, it is the special significance of salubrious/deleterious SD in early childhood. Thus, while I would agree with you that there is a lot we don’t know, I would also want to say that what we do currently know about the effects of deleterious SD in early childhood is more than sufficient to generate a panoply of public policy interventions geared at intensive early childhood development.
Thus, I still have trouble seeing what these kinds of studies really add in the population ethics and public policy context. They are firmly planted in the grand (mechanically) objectifying traditions of modern Western science; they provide rhetorically powerful means of examining the mechanisms by which deleterious SD in early childhood shape neuropathologies, cognitive development, and health across the life span (Indeed, given what we know about the stunning rhetorical power of brain images, one can barely understate its capacity here). There’s really nothing wrong with this in itself, although the risks of neuroreductionism are quite real and quite problematic, especially cast against the magic-bullet-loving individualist aspects of American social and political culture.
But we already knew an enormous amount about the effects of deleterious SD in early childhood on health across the lifespan (multiple lifespans, actually). I guess where we differ, if we do, is that I have trouble seeing how identifying biological markers in and of itself is anything more than an incremental change which must be balanced against the very significant risks of reductionism and stigma on the other side.
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