Growing up in a low-income household is associated with smaller hippocampal volume and more negative mental health symptoms in children, but new research suggests these effects can be offset by well-funded anti-poverty programs.
Investigators analyzed data on over 10,000 children living in high- and low-income households and measured associations between cash assistance programs, Medicaid expansion, and hippocampal volume.
Children growing up in poverty had smaller hippocampal volume, compared with those living in higher-income households — especially those residing in states with a higher cost of living — an effect that is offset in states with stronger social safety nets. The magnitude of disparities in brain structure was reduced by one third and disparities in mental health by almost 50% in states with more generous anti-poverty programs.
"We consider this to be pretty solid evidence that policy decisions on things like Medicaid expansion and the generosity of cash assistance for families in poverty matter for the brain development and mental health of children from those families in a measurable and significant way," study investigator David Weissman, PhD, a postdoctoral fellow in the Stress and Development Lab at Harvard University, Cambridge, Massachusetts, told Medscape Medical News.
The study was published online May 2 in Nature Communications.
Lower Income, Lower Brain Volume
Lower family income has consistently been associated with smaller hippocampal volume in children and higher levels of internalizing and externalizing psychopathology, the authors note.
The strength of these associations between low income, mental health, and brain outcomes have been related to broad social and economic factors, including a higher cost of living that magnifies the impact of having a low income, the investigators note. However, these effects may be counterbalanced by the "generosity of the social safety net," including cash assistance programs and programs providing benefits for specific needs such as Medicaid, they note.
"We know, based on theory and evidence in multiple behavioral science disciplines, that structural characteristics like public policies and macroeconomic conditions have large influences on people’s lives," said Weissman.
"But, because psychology and neuroscience tend to focus on individuals and their immediate environment and tend to conduct studies with at most hundreds of participants at a single place and time, we seldom have the opportunity to examine how these structural characteristics relate to things like brain structure and mental health," he added.
The national multi-site Adolescent Brain and Cognitive Development (ABCD) study provides that opportunity, said Weissman. It evaluates the impact on children’s brain development from the macrostructural characteristics of US states, including the generosity of anti-poverty policies and cost of living.
The current study focused on 10,633 children who participated in the ABCD study (aged 9-11 years) across 17 states.
After controlling for total intracranial volume, age, and sex, the researchers found hippocampal volume was larger in participants with higher family income (B = 62.71; 95% CI, 46.91-78.52; β = .079; P < .001).
Conversely, family income was negatively associated with internalizing and externalizing behaviors (B = -59; 95% CI, -.88 to -.030; β = -.058; P < .001; and B = -1.50; 95% CI, -1.96 to -1.05; β = -.152; P < .001).
There was a three-way interaction between family income, cost of living, and generosity of cash assistance programs in predicting hippocampal volume (B = -3.64; 95% CI, -5.91 to -1.36; P = .002).
A Levelling Effect
In high cost-of-living states providing more generous cash benefits for low-income families, socioeconomically related disparities in hippocampal volume were reduced by ~34%, suggesting the link between family income and hippocampal volume in these states was similar to the link between family income and hippocampal volume in the lowest cost-of-living states.
However, the interaction between cost of living and cash benefits was only significant when the log-income-to-needs ratio was low (~1 SD below the mean, equivalent to about 80% of the poverty line), suggesting that "cost of living and the generosity of anti-poverty policies are associated with hippocampal volume only for children in low-income families who are eligible for the benefits of these programs."
A similar three-way interaction was observed between family income, cost of living, and Medicaid expansion in relation to hippocampal volume.
The results were similar when researchers examined the three-way interactions of family income, cost of living, and state minimum wage vis-à-vis hippocampal volume, with the same pattern as for cash assistance and Medicaid expansion.
When researchers examined the link between family income and adolescent internalizing problems, they found similar results. More generous cash benefits were associated with income disparities in internalizing symptoms that were ~48% lower in high vs low cost-of-living states.
In sensitivity analyses, the researchers accounted for social, economic, and political characteristics that might have provided alternative explanations for these patterns. The findings remained "robust" after controlling for numerous state-level characteristics and their interaction with family income.
"These results suggest that government anti-poverty programs work at reducing those impacts, and we think that policymakers should take this into consideration as they weigh decisions like renewing the extended child tax credit, which cut child poverty in half," said Weissman.
"As for clinicians and the health system, I think this study potentially emphasizes the value of ensuring that patients are aware of and accessing the government benefits that they are eligible for in order to help reduce socioeconomic disparities in health," he said.
Commenting for Medscape Medical News, Nora Volkow, MD, director of the National Institute on Drug Abuse (NIDA) at the National Institutes of Health, described the study as "unique" because it "dovetails with existing findings that living in poverty is detrimental to the human brain, but it brings understanding of how poverty programs that support families with low income ultimately influence those trajectories, which is totally novel."
While NIDA played a key role in conceptualizing the ABCD study, Volkow was not involved in conducting it.
Anti-poverty interventions "will lead to much better outcomes as these children grow into adults," Volkow said. "Those adults will also have children and they, in turn, will have better outcomes, so intervention will have a significant positive effect on the person as well as a transgenerational effect."
Also commenting for Medscape Medical News, Joan Luby, MD, Samuel and Mae S. Ludwig professor of psychiatry (child), Washington University School of Medicine, St. Louis, Missouri, called the findings "very important because they really show for the first time that variation in public policies that support families have a tangible impact on the developing brain."
Luby, who was not involved with the study, said it shows "for the first time in a clear way that public policy has a meaningful impact on this risk trajectory. It is a finding that policymakers should pay attention to."
Support for this research came from the National Institute of Mental Health (NIMH), and the National Science Foundation. The authors and Volkow declare no relevant financial relationships. Luby receives funding from NIMH.
Nat Comm. Published online May 2, 2023. Full text.
Batya Swift Yasgur, MA, LSW, is a freelance writer with a counseling practice in Teaneck, New Jersey. She is a regular contributor to numerous medical publications, including Medscape and WebMD, and is the author of several consumer-oriented health books as well as Behind the Burqa: Our Lives in Afghanistan and How We Escaped to Freedom (the memoir of two brave Afghan sisters who told her their story).
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Cite this: Well-Funded Anti-Poverty Programs Protect Kids' Brains - Medscape - May 19, 2023.