Scientists found that the brain differences blamed on poverty for decades actually come down to two things every parent can control: sleep and stress

Article:

For decades, research connecting poverty to children’s brain development has produced a consistent but frustratingly vague finding: kids from lower-income families tend to show measurable differences in brain structure and function compared to kids from higher-income families. The finding was real, but it was also a black box. Income itself does not directly touch a child’s brain. Something happens in between, some pathway through which a family’s financial circumstances become biological reality inside a developing nervous system. Nobody had been able to identify what that pathway actually was.

A study published by researchers at Washington University School of Medicine, using brain scans from nearly 12,000 children in the Adolescent Brain Cognitive Development Study, just identified it. And the answer is not what most people would guess.

The 649 Variables

The research team, led by Scott Marek, a radiologist at WashU, set out to systematically test which of 649 different variables in children’s lives most strongly predicted differences in brain structure and brain activity. The variables covered an enormous range: mental and physical health, parenting style, friendships, substance use, exposure to noise and pollution, cognitive test scores, screen time, and socioeconomic measures including family income, neighborhood wealth, homeownership, and access to transportation.

This is what scientists call a brain-wide association study, an approach that has historically required massive sample sizes to produce reliable results. With nearly 12,000 children, the WashU team had the statistical power to rank all 649 variables against two measures of brain biology: cortical thickness, which reflects the physical structure of the brain’s outer layer, and functional connectivity, which measures how actively different brain regions communicate with each other during rest.

Out of 649 variables, 40 showed meaningful links to brain function. Of those 40, 37 fell into the socioeconomic category. For brain structure, the picture was nearly identical: 35 of the top 40 variables were socioeconomic. Family income, neighborhood opportunity, homeownership, and access to transportation dominated the rankings in a way that surprised even the researchers conducting the study.

Why the Result Confused the Researchers

“The pattern that emerged was, at first, very confusing to us,” Marek said. The confusion came from where in the brain these socioeconomic differences were showing up. If income and neighborhood opportunity were affecting children’s brains through the pathways most researchers had assumed, the differences should have concentrated in regions associated with higher cognitive functions: attention, memory, executive function, the brain systems most commonly discussed in relation to academic achievement and opportunity gaps.

That is not what the data showed. The strongest socioeconomic associations were concentrated in brain regions involved in sensory processing and motor control, areas that handle basic functions like processing what the body feels, sees, and how it moves, rather than the higher-order cognitive systems everyone expected to find at the top of the list.

This sent the research team looking for an explanation that could connect socioeconomic circumstances to sensory and motor brain regions specifically, rather than to the attention and memory systems that prior research had focused on.

The Circuits That Keep You Awake

The explanation the team arrived at involves brain circuits responsible for arousal, the systems that regulate wakefulness and alertness throughout the day. These circuits are not isolated to one brain region. They run through and influence the sensory and motor areas where the socioeconomic associations were strongest, because an alert, well-regulated nervous system processes sensory information and coordinates movement differently than a nervous system operating under chronic sleep deprivation or persistent stress.

“The data are screaming that we should be looking at sleep, stress, and screens if we want to get somewhere,” Marek said. Children growing up in lower-income neighborhoods with less social support showed brain differences specifically associated with reduced sleep and elevated stress. Screen time, which is itself linked to both reduced sleep and lower socioeconomic status, also emerged as part of the same cluster of associated factors.

The researchers describe this as socioeconomic status becoming biologically embedded in the brain, not through some direct mechanism where poverty itself rewires neural tissue, but through the downstream effects of chronic sleep disruption and persistent stress that are more common in lower-income households and neighborhoods. A child whose neighborhood lacks safe outdoor space, whose household faces unpredictable work schedules, whose access to consistent routines is disrupted by financial instability, experiences chronic activation of stress response systems and frequently compromised sleep. Those two factors, operating continuously across years of development, appear to leave a measurable signature in the brain’s arousal-related circuitry and the sensory and motor regions that circuitry influences.

What This Does Not Prove

The researchers and outside experts were careful about the limits of what a study like this can establish. This is a brain-wide association study, which means it identifies statistical correlations between exposures and brain measurements at a single point in time. It does not, on its own, prove that socioeconomic factors are causing the brain differences observed, and it does not prove that intervening on sleep or stress would change a child’s brain development trajectory.

Janet Currie, a health economist at Yale University who was not involved in the study, raised the key question directly: if you could follow people over time, would you find that changes in neighborhood socioeconomic status predicted changes in brain development? That longitudinal question, whether the relationship is causal and whether it is reversible, is the one this cross-sectional snapshot cannot answer on its own.

Dr. Nico Dosenbach, a co-author from WashU Medicine, noted that factors more traditionally associated with brain development, like IQ and mental health measures, did show some influence in the data, just a smaller one than the socioeconomic cluster that dominated the rankings. The finding does not erase those other factors. It reorders their relative importance in a large, well-powered dataset in a way that prior smaller studies could not.

The Reframe That Matters

What makes this finding significant is not that socioeconomic status affects children’s brains. That has been documented for years. What is significant is the specificity of where and how. Previous research often implicitly or explicitly suggested that poverty’s effects on the brain ran primarily through cognitive and academic pathways, the brain systems involved in learning, attention, and executive function, the systems most directly tied to school performance and the achievement gaps that dominate education policy conversations.

This study points somewhere different: toward the basic biological infrastructure of sleep and stress regulation, systems that sit upstream of cognition rather than within it. If a child’s arousal and stress regulation systems are being shaped by chronic sleep disruption and persistent stress associated with their socioeconomic environment, the downstream effects on attention, learning, and emotional regulation may be a consequence of that more basic disruption rather than a separate, parallel effect.

This reframing matters for where interventions might be targeted. Sleep environment, household stress levels, and screen time patterns are concrete, addressable targets in a way that the broad category of socioeconomic status is not. They will not change the underlying economic circumstances of a family, but they represent specific mechanisms through which those circumstances appear to be reaching a child’s developing brain, and mechanisms that, unlike income itself, can potentially be addressed directly within a household regardless of its financial situation.

The researchers are now planning to follow this cohort over time, tracking whether changes in sleep, stress, and socioeconomic circumstances correspond to changes in brain development as these children grow. That longitudinal data, not yet available, will be what determines whether this finding becomes the foundation for new approaches to supporting child brain development, or remains a striking snapshot of a single moment in nearly 12,000 young lives.

Sources:

Marek, S., Dosenbach, N.U.F., et al. Socioeconomic factors influence children’s brain structure and function. Proceedings of the National Academy of Sciences, June 11, 2026. DOI: 10.1126/science.aee6213

eurekalert.org/news-releases/1131245 statnews.com/2026/06/11/socioeconomic-status-impact-brain-development npr.org/2026/06/11/nx-s1-5849937/child-brain-development-stress-sleep-neighborhood-economics