Our brains shape who we are, but what shapes our brains? Researchers at Washington University School of Medicine in St. Louis sought to answer that question by examining how a wide range of childhood experiences and life circumstances influence brain development. After analyzing hundreds of biological, psychological, social and environmental factors, the researchers found that socioeconomic conditions — including a family’s financial situation and the opportunities available in a child’s neighbourhood — had the strongest connection to children’s brain structure and function. The findings, published June 11 in Science, suggest that social and economic conditions may leave a deeper imprint on children’s brains than many previously studied factors.
The research team analyzed brain scans and developmental data from nearly 12,000 children aged 9 to 10 participating in the NIH-funded Adolescent Brain Cognitive Development Study. Using MRI scans, the scientists examined relationships between brain structure, brain connectivity and 649 variables grouped into 12 categories, including socioeconomic status, screen time, cognitive abilities, physical and mental health, parenting, personality, medical history and environmental influences. Of all the variables examined, socioeconomic factors consistently showed the strongest links to brain development. Socioeconomic conditions accounted for roughly 16% of the variability in measures of brain function, greatly exceeding the influence of IQ, parenting style or health history.
Among the strongest socioeconomic influences were family income, homeownership, neighbourhood poverty rates, transportation access and overall community resources. Of the 40 variables most strongly associated with brain function, 37 were socioeconomic, while 35 of the top 40 linked to brain structure were also socioeconomic. Researchers also found that sleep quality, screen time and chronic stress were closely connected to the same brain regions influenced by socioeconomic conditions. According to senior author Nico U. Dosenbach, the findings suggest that socioeconomic disadvantage may affect children’s brains indirectly through daily burdens such as stress and disrupted sleep.
The brain regions most affected were areas involved in motor and sensory processing, which are particularly sensitive to sleep deprivation and chronic stress. In contrast, regions associated with higher-level thinking and problem-solving showed much weaker connections to socioeconomic conditions. The researchers emphasized that the findings do not indicate that children from lower socioeconomic backgrounds are less intelligent. Rather, their brains may reflect the effects of ongoing stress and fatigue. The researchers noted that sleep and stress are modifiable factors, raising hope that targeted interventions could help reduce some of the observed brain differences linked to socioeconomic disadvantage.
The study also challenged long-standing assumptions about IQ and brain biology. For decades, scientists have searched for physical markers of intelligence within the brain, often reporting associations between IQ scores and features such as cortical thickness. However, when the researchers statistically adjusted for socioeconomic factors, approximately 70% of the previously observed relationships between IQ and brain measures were no longer statistically significant. In a separate analysis restricted to children from high socioeconomic backgrounds, IQ showed no meaningful correlation with brain structure or function.
The findings suggest that many earlier studies linking IQ to brain features may actually have been capturing the effects of socioeconomic conditions rather than innate intelligence. First author Scott Marek described socioeconomic status as the “elephant in the brain” because of its overwhelming influence across the analyses. The researchers concluded that children’s environments — especially factors related to stress, sleep and economic opportunity — shape brain development in profound ways. Importantly, because sleep and chronic stress can potentially be improved, the study points toward practical opportunities to support healthier brain development for children facing socioeconomic disadvantage.
More information: Scott Marek et al, Patterns of brain-wide associations reflect socioeconomics, Science. DOI: 10.1126/science.aee6213
Journal information: Science Provided by Washington University in St. Louis
