Poverty in kids assoc with decreased brain volume

 

We seem to be marching forward to trimming the social safety net for people below the Federal poverty level, decreasing their access to adequate food, housing, and medical care. In this light, there was a really important article showing that children in lower income families without necessary social benefits have reduced hippocampal volume in the brain as well as higher internalizing psychopathology. of note, increased access to cash benefits pretty dramatically decreased these disparities (see poverty adol brain changes NatureCommun2023 in dropbox, or doi.org/10.1038/s41467-023-37778-1)

 

Details:

-- data were from the Adolescent Brain and Cognitive Development (ABCD) study of 10,633 youths aged 9-11 (5115 female) across 21 sites in 17 states in the US

    -- ABCD includes lots of self-reported behavioral data as well as neuroimaging findings to assess brain development

-- the researchers evaluated several macrostructural characteristics, including anti-poverty policies and cost of living in the states

-- they also assessed participants’ internalizing or externalizing psychopathology, as expressed in the Child Behavior Checklist (CBCL) for both boys and girls:

    -- internalizing behaviors: anxiety/depression, being withdrawn

    -- externalizing behaviors: aggressive and destructive behaviors

-- for the evaluation of state-level benefits, they assessed the Earned Income Tax Credit (EITC, which provides cash credit to increase the income of working families that are below a certain income level), the Temporary Assistance for Needy Families (TANF, temporary cash assistance to families that are out of work), and Medicaid (comparing states that opted in vs out of Medicaid expansion with the Affordable Care Act)

-- primary outcomes: hippocampal volume by MRI, internalizing and externalizing psychopathology by questionnaire, and the relationship with macrostructural economic factors (family income, cost of living in the state, antipoverty programs, state-provided Medicaid expansion)

 

 Results:

-- family income:

    -- hippocampal volume (controlling for total intracranial volume, age, and sex): lower income was associated with decreased hippocampal volume

    -- lower income was also  associated with both internalizing an externalizing problems

 

-- state-level effects:

    -- the largest difference in hippocampal volume was between high vs low cost of living states: the higher the cost of living, the more hippocampal volume loss.

        -- states with high cost of living and high cash benefits:  hippocampal volume was 60 mm³ larger than for those in states with average cost of living and low cash benefits (ie, in high cost of living states, the availability of cash benefits for those living in poverty was  associated with significantly higher hippocampal volume, to the point that the decrease in hippocampal volume in high cost of living states with these anti-poverty programs was similar to that of low cost of living states with less generous programs)

        -- overall, the difference in hippocampal volume between low and high income participants in high cost of living states with low cash benefits was 195 mm³, but only 129 mm³ in states where both the cost of living and cash benefits were high: ie, more generous cash benefits were associated with income disparities in hippocampal volume that was 34% lower in states with high (vs low) cost of living.

    -- in high cost of living states, the disparities in hippocampal volume between high and low income participants were 43% lower in states that expanded Medicaid vs states that did not

 

-- internalizing and externalizing psychopathology:

    -- income was associated with both internalizing and externalizing psychopathologies

        -- more generous cash benefits were associated with decreased disparities in internalizing symptoms: the disparities were 48% lower in high (vs low) cost of living states

        -- and they were lower in states that expanded Medicaid programs or had more generous antipoverty assistance programs

 

-- sensitivity analyses:

    -- results were the same when controlling for some other reasons that could explain the differences in outcomes besides the anti-poverty programs: eg, population density, economic inequality, unemployment rate, tightness/looseness regarding adherence around cultural rules/norms, political preferences, women's political participation, reproductive rights, incarceration rates, state-funded preschool enrollment, and reading proficiency in students from low-income backgrounds

    -- analysis stratified by different income levels: using a higher income cutoff that that did not correspond with eligibility for benefits: no finding of benefit by adding the cash benefit programs (ie, it was only the more impoverished people who benefited from the anti-poverty programs)

 

Commentary:

-- the hippocampus is an area of the brain deep in the temporal lobe. Its major role is in learning and forming memories: regulating learning, memory encoding, memory consolidation, and spatial navigation; the hippocampus is very sensitive to stress, depression, and sleep deprivation, all being associated with decreased hippocampal volume and function, and clinically with cognitive impairment overall as well as decreased academic achievement.

-- the ABCD database had previously been accessed finding that there was a relationship between brain structure and racism, sexism, and anti-immigration attitudes, specifically in states with social policies and prejudicial attitudes: ie, those states with “societal-level conditions, cultural norms and institutional policies and practices that constrain the opportunities, resources, and wellbeing of the stigmatized” (see https://pubmed.ncbi.nlm.nih.gov/34481917/ )

 

-- the results of this study are neither new nor unexpected. Several other studies have found similar results. for example, a longitudinal cohort study of 389 developing children and adolescents found that poverty was associated with marked structural changes (by brain MRI), worse with increasing poverty, especially in the gray matter of the brain overall, the frontal lobe, the temporal lobe and the hippocampus. They also found a relationship with poorer academic achievement and poorer functioning in standardized tests, and they calculated that about 20% of of the test gap could be explained by maturational lags in the frontal, temporal lobes, and hippocampus (see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4687959/ )

-- other studies have also found that lower levels of family income are associated with higher levels of internalizing and externalizing psychopathology

-- Medicaid expansion has been shown to lead to lower psychological stress

-- the presumed mechanism here is that children growing up in poverty are exposed to more stressful life events such as violence in the community, conflicts, and more often having separation from their caregivers (children living in poverty, and especially in families of color, are more likely to be taken away from their families by state agencies for social reasons, more so than white children from higher income families with similar issues)

-- there are also concerns about the levels of federal resources distributed to people: those living in higher cost of living states typically get the same cash value of benefits as those living in less expensive states…

  

-- the brief summary of the above trial:

    -- lower family income is associated with smaller hippocampal volume, and greater internalizing and externalizing psychopathology in early adolescence.

    -- the magnitude of the changes in hippocampal volume is influenced strongly by the cost of living of the states (higher cost of living is associated with smaller hippocampal volume) and particularly with the generosity of antipoverty programs (the more generous, the less severe effect on the hippocampus)

    -- more generous antipoverty programs were associated with less internalizing, similar to the findings in lower cost of living states

 

-- this trial is a strong addition to the prior trials in that large numbers of children were involved, they assessed both hippocampal volume as well as some aspects of psychopathology, and they were able to compare different states with different costs of living, different approaches to deal with the social safety net, different political orientations (some states declining Medicaid expansion, though at the predicted and now documented detriment to many people). They were therefore able to assess associations between the macro-social context and important health outcomes in children

-- but, there always remains a concern in this type of observational study: is the change in hippocampal volume related to the lack of adequate financial resources? or is it related to the multitude of other problems associated with poverty, such as the array of associated stressors (eg community violence, overcrowding, housing insecurity). We do know that stress itself is associated with decreased hippocampal volume and function. perhaps there are also other issues in play here, such as lack of intellectual stimulation (perhaps single parent family, perhaps parent(s) too busy to spend time with individual children with school work, perhaps parent(s) with insufficient education or knowledge of English to help), etc.  In this light, there is an ongoing study to answer this question: 1000 low-income mothers with newborns were randomized to receive $333 vs $20 cash monthly for the first several years of the child's life, then assessing the children's developmental outcomes, results pending (for more details, see: https://publications.aap.org/pediatrics/article/148/4/e2020049702/181277/Baby-s-First-Years-Design-of-a-Randomized?autologincheck=redirected ). A preliminary report from this study found that a substudy of infants at 1 year in the high-cash gift group had more high-frequency band power on EEG testing, a finding that is not found in those children facing other forms of early adversity (see poverty reduction improve EEG at 1 yr old PNAS2021 in dropbox, or  https://doi.org/10.1073/pnas.211564911)

    -- a recent blog reviewed an article finding that perceived stress decreased cognitive function, likely related to the multiple physiologic perturbations associated with stress (see http://gmodestmedblogs.blogspot.com/2023/04/stress-decreases-cognitive-function.html for an elaboration of these many perturbations)

 

Limitations:

-- this was a large, data-mining study and there may well be other important unincorporated stressors (as noted above) that may be significantly related to their measured outcomes of hippocampal volume and psychopathology.

    -- there are likely other factors not mentioned that might contribute to more stress and more hippocampal volume loss, such as lack of personal support systems, lack of exercise, housing or food insecurity, feeling unsafe in the community, personally experiencing or witnessing violence, etc

    -- as an observational study, they are unable to attribute causation, in light of these many types of unincorporated stressors in their database

-- it is always difficult to generalize results from a study in several states to the larger community (though better having 17 states than fewer). but there are clearly some deficiencies. For example, they cannot find states with high cost of living that had the same lack of social supports as states with lower cost of living

-- the use of state-level data provides an average, but there could be very different circumstances in some parts of the state (eg rural areas) vs others; in addition, the cost of living could vary in different areas within the same state

-- this study was only of 9-11 year olds, and may not be generalizable to other age groups

-- the brain overall, including the hippocampus, demonstrates impressive neuroplasticity (eg see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3012424/ ), whereby certain factors (including stress) lead to atrophy but other factors (including exercise) enhance neurogenesis. It would be important to have long-term results of this study 

-- some of the data (internalizing/externalizing psychopathology), were self-reported and may not be truly representative of the situation

 

so, these results further elucidate the cycle of poverty in the US:

    -- poverty is associated with an array of adverse phenomena: less access to adequate housing (and more often in communities with higher stress levels and violence), healthy foods (as well as food insecurity), resources (eg state-of-the art computers, internet access), and often less ability to achieve a higher educational level (parents working many hours and not at home to help the kids, parents who may not speak English well or have the educational background to help their children academically: ie, fewer helicopter parents there). and all of this is exacerbated in single parent families

    -- the reality, likely well-understood by many, is that very few growing up in poverty have upward social mobility (the UK is at the bottom for Europe in social mobility; the US is no better: https://www.jstor.org/stable/2779760 )

    -- the dominant ideology in the US is that those in poverty are inferior, especially those of color, that it is largely their faults, and that is okay to have the huge and increasing levels of income inequality and general inequities. and this, in and of itself, may decrease peoples’ motivation to break the cycles, thereby reinforcing the finding in this study above of "internalizing psychopathology"

    -- there is the other issue of social drift: people who have significant medical/mental health issues tend to be poorer and live in poorer communities, though many of their problems could well be improved with appropriate access to health care and social supports

    -- and the conclusions of the above study that poverty itself is associated with significant changes in brain architecture that are predicted to lead to lower ability to excel academically, further reinforces this cycle

    -- we also have the rather striking issue in the US that the poorest states (the ones with the health outcomes similar to poor countries) tend to be the ones that rejected Medicaid expansion, with the anticipated significant health (including mental health) effects

 

-- it seems pretty intuitive that even small investments in social safety net programs are not only healthy and humane, but may well be an important factor in helping break this adverse cycle of poverty

    -- unfortunately the US government’s current approach is to decrease safety-net programs, coupled with underfunding the IRS.  This latter initiative will further limit the IRS’s ability  to pursue the immensely wealthy who dodge their taxes to the point that extraordinarily rich people pay no or minimal taxes both through tax loopholes and conscious deceit, making it even more difficult to fund needy social programs

    -- a notable tax cut by then president Trump for $2.3 trillion basically fed the coffers of the very wealthy corporations, with only a small and transient bump in the overall economy (see https://www.vox.com/policy-and-politics/2017/7/12/15959210/trump-tax-cuts-reform-tax-policy-center ) 

 

-- so, the important finding of the study  is that adequate economic supports do go a long way to decrease adverse effects on brain architecture of children. it is certainly a public good and current public health imperative to decrease poverty now, with the relatively small amount of money needed (vs the $2.3 Trillion trump fiasco), to help break the ramifications of the cycle of poverty.  Though we really need to address the larger issue of general inequities in society, which profoundly affect the ability of people in the long run to achieve their potential, in oh-so-many ways...

 

geoff

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