Poverty is a Neurotoxin – Quality Preschool: An Antidote

Mahatma Gandhi once said that Poverty is the worst form of violence.  At the very least it appears to be a neurotoxin.  Evidence continues to build a solid case for the notion that poverty itself is self-propagating and that the mechanism of this replication takes place in the neuro-anatomy of the innocent children reared in environmental deprivation.

 

In my article titled The Effects of Low SES on Brain Development I review an article that provides clear quantitative data that indicates that children raised in low SES environments have diminished brain activity relative to their more affluent peers.  The impact of low SES on brain activity was so profound that the brains of these poor kids were comparable to individuals who had had actual physical brain damage.  This data gathered through EEG is a non-specific measure that provides no clear understanding of what underlies this diminished functioning.  In other words, it evidences diminished brain activity, but it does not specifically identify what has occurred in the brain that is responsible for these differences.

 

Jamie Hanson and colleagues from the University of Wisconsin-Madison and Harvard University published a paper titled Association Between Income and the Hippocampus in the peer reviewed on-line journal PLoS ONE that points to one possible culprit.  Their study shows in a measurable way, how poverty actually hinders growth of the hippocampus, a very important brain region associated with learning and memory.

 

In non-human animal studies, it has been shown that environmental enrichment is associated with “greater dendritic branching and wider dendritic fields; increased astrocyte number and size, and improved synaptic transmission in portions of the hippocampus” (Hanson et. al. 2011).  This essentially means that environmental enrichment enhances the density and functioning capacity of the hippocampus.  In humans, parental nurturance, contact, and environmental stimulation has been associated with improved performance on tasks (long-term memory formation) greatly influenced by the hippocampus. On the flip side, it has also been demonstrated that stress, inadequate environmental nurturance and low stimulation have the opposite affect (thinning hippocapmal density).

 

Hanson et. al., (2011) hypothesized that hippocampus density would be positively related to gradients in parental income.  Affluent children would evidence more hippocampal density (associated with better learning, memory, emotional control) while their low income counterparts would evidence diminished levels of density.  They used datea from MRI imaging studies to measure the actual hippocampal gray matter density in a large cross section of children (ages 4-18 years old) across the United States.  They also collected data on the income and education level of each participant’s parents.  As a control measure, they also quantified the whole-brain volume and the density of the amygdala, a brain region that does not vary as a function of environmental perturbations or enrichment.   These latter variables were important because they assist in ruling out brain size variation associated with other confounding variables.  They hypothesized that these latter measures would not vary associated with income.

 

 

Their measures confirmed each of their hypotheses.  Amygdala and whole brain volume did not vary associated with parental income but hippocampal density did.  Those with parents at the lower end of the income spectrum evidenced lower hippocampal density than those children from more affluent families.  They wrote that “taken together, these findings suggest that differences in the hippocampus, perhaps due to stress tied to growing up in poverty, might partially explain differences in long-term memory, learning, control of endocrine functions, and modulation of emotional behavior” (Hanson, 2011).

 

The authors carefully noted that this correlation is not necessarily indicative of causation – and that more specific longitudinal measures along with direct measures of cognitive functioning, environmental stress,  and stimulation are necessary to truly understand the association between income and these neurobiological outcomes.  But they also warned that the data set was limited to children unaffected by mental health issues or low intelligence.  As such, the data set likely underestimates the actual hippocampal volume variation because children at the lower end of the income spectrum have disproportionately high levels of these mental health and low intelligence issues.

 

These results confirm and fit with a growing and already substantial set of findings that implicate poverty as a neurotoxin that causes a self sustaining feedback loop.  Poverty seems to weaken the foundation on which fundamental skills and capabilities are built that ultimately facilitate adaptive functioning and positive societal contributions.  A weak foundation hinders such capacities.

 

I have previously posted articles titled Halting the Negative Feedback Loop of Poverty: Early Intervention is the Key, Poverty Preventing Preschool Programs: Fade-Out, Grit, and the Rich get Richer, and The Economic, Neurobiological, and Behavioral Implications of Poverty.  In these articles I review various other studies that address this issue, but I also highlight the steps that can be taken to remediate the problem.  There really is not much question about the needed steps we as a society should take.    A recent series of articles published in the UK’s Lancet, drives this point home!

 

In one particular article, titled Strategies for reducing inequalities and improving developmental outcomes for young children in low-income and middle-income countries, the authors noted that:

 

“A conservative estimate of the returns to investment in early child development is illustrated by the effects of improving one component, preschool attendance. Achieving enrolment rates of 25% per country in 1 year would result in a benefit of US$10·6 billion and achieving 50% preschool enrolment could have a benefit of more than $33 billion (in terms of the present discounted value of future labour market productivity) with a benefit-to-cost ratio of 17·6. Incorporating improved nutrition and parenting programmes would result in a larger gain.”

 

The monetary value alone seems sufficient to motivate implementation.  For each dollar spent on quality preschool programs, we ultimately gain up to $17.60 in labor market productivity alone.  This does not account for the decreased expenditures on special education, incarceration, and other social safety net programs.  Quality preschool programing has been shown to increase high school graduation rates and home ownership rates.  If we as a society, are truly driven to promote human flourishing, equal opportunity for all, and a level playing field, then we must, I argue, take action with regard to providing universal access to quality preschool programs particularly for poor children.  What I propose is not a hand-out, but a fiscally responsible hand-up that benefits each and every one of us.

 

References:

 

Engle, P., L., Fernald, L. CH., Alderman, H., Behrman, J., O’Gara, C.,  Yousafzai A.,  de Mello M. C., Hidrobo, M.,  Ulkuer, N., Ertem, I., Iltus, S., The Global Child Development Steering Group. (2011).  Strategies for reducing inequalities and improving developmental outcomes for young children in low-income and middle-income countries. The Lancet, Early Online Publication, 23 September 2011. doi:10.1016/S0140-6736(11)60889-1

 

Hanson, J.L., Chandra, A., Wolfe, B. L., Pollak, S.D., (2011).  Association between Income and the Hippocampus. PLoS ONE 6(5): e18712. doi:10.1371/journal.pone.0018712