The Role of School Environment in Brain Structure, Connectivity, and Mental Health in Children: A Multimodal Investigation

Aspects of Area Deprivation Index in Relation to Hippocampal Volume Among Children

Importance

Area deprivation index (ADI) has been shown to be associated with reduced hippocampal volume (HV) among youths. The social environment may interact with the association between ADI and HV.

Objective

To investigate which aspects of ADI are uniquely associated with bilateral HV and whether school and family environments have moderating interactions in associations between ADI and HV.

Design, Setting, and Participants

This cross-sectional study used data from the Adolescent Brain and Cognitive Development (ABCD) study. Participants aged 9 and 10 years were recruited from 21 sites in the US between September 2016 and August 2018. Data analysis was performed between March 2023 and April 2024.

Exposures

ADI aspects were derived from participant primary home addresses provided by parents or guardians.

Main Outcomes and Measures

HV was automatically segmented from structural brain images ascertained from magnetic resonance imaging. Multiple generalized linear mixed modeling tested associations between 9 indices of ADI and bilateral HV, with family groups and recruitment sites as random effects. After stepwise backward selection, models were adjusted for individual-level covariates, including age, sex, race and ethnicity, parental education, household income, and estimated intracranial volume.

Results

This study included 10 114 participants aged 9 and 10 years (median [IQR] age, 9.92 [9.33-10.48] years; 5294 male [52.3%]; 200 Asian [2.0%], 1411 Black [14.0%], and 6655 White [65.8%]; 1959 Hispanic [19.4%]). After stepwise backward selection and adjusting for covariates, only the percentage of neighborhood-level single-parent households was associated with right HV (adjusted β per 1-SD increase in single-parent households, -0.03; 95% CI, -0.06 to -0.01; P = .01). School environment interacted with neighborhood-level single-parent households in its association with right HV (adjusted β per 1-SD increase in score, 0.02; 95% CI, 0.01 to 0.03; P = .003), such that there was an inverse association only among those at a school with the mean environment score (adjusted β per 1% increase in single-parent households, -0.03; 95% CI, -0.05 to -0.01; P = .02) and worse (-1 SD score) school environment score (adjusted β per 1% increase in single-parent households, -0.05; 95% CI, -0.09 to -0.01; P < .001) but not among those at better (+1 SD score) school environments.

Conclusions and Relevance

In this study, an increased percentage of neighborhood-level single-parent households was associated with reduced right HV among children in schools with the mean or worse but not better environment score. These findings suggest that longitudinal research concerning the association of neighborhood-level characteristics and school environments with hippocampal development may be warranted to better understand complex interactions between various social factors and child neurodevelopment and mental health outcomes.

Pathways link environmental and genetic factors with structural brain networks and psychopathology in youth

Adolescence is a period of significant brain development and maturation, and it is a time when many mental health problems first emerge. This study aimed to explore a comprehensive map that describes possible pathways from genetic and environmental risks to structural brain organization and psychopathology in adolescents. We included 32 environmental items on developmental adversity, maternal substance use, parental psychopathology, socioeconomic status (SES), school and family environment; 10 child psychopathological scales; polygenic risk scores (PRS) for 10 psychiatric disorders, total problems, and cognitive ability; and structural brain networks in the Adolescent Brain Cognitive Development study (ABCD, n = 9168). Structural equation modeling found two pathways linking SES, brain, and psychopathology. Lower SES was found to be associated with lower structural connectivity in the posterior default mode network and greater salience structural connectivity, and with more severe psychosis and internalizing in youth (p < 0.001). Prematurity and birth weight were associated with early-developed sensorimotor and subcortical networks (p < 0.001). Increased parental psychopathology, decreased SES and school engagement was related to elevated family conflict, psychosis, and externalizing behaviors in youth (p < 0.001). Increased maternal substance use predicted increased developmental adversity, internalizing, and psychosis (p < 0.001). But, polygenic risks for psychiatric disorders had moderate effects on brain structural connectivity and psychopathology in youth. These findings suggest that a range of genetic and environmental factors can influence brain structural organization and psychopathology during adolescence, and that addressing these risk factors may be important for promoting positive mental health outcomes in young people.

Assessment of Parent Income and Education, Neighborhood Disadvantage, and Child Brain Structure

IMPORTANCE

Although different aspects of socioeconomic status (SES) may represent distinct risk factors for poor mental health in children, knowledge of their differential and synergistic associations with the brain is limited.

OBJECTIVE

To examine the independent associations between distinct SES factors and child brain structure.

DESIGN, SETTING, AND PARTICIPANTS

We used baseline data from participants aged 9 to 10 years in the Adolescent Brain Cognitive Development (ABCD) study. These data were collected from 21 US sites between September 2017 and August 2018. Study participants were recruited from schools to create a participant sample that closely reflects the US population.

EXPOSURES

Neighborhood disadvantage was measured using the area deprivation index. We also used data on total parent or caregiver educational attainment (in years) and household income-to-needs ratio.

MAIN OUTCOMES AND MEASURES

T1-weighted magnetic resonance imaging was used to assess measures of cortical thickness, surface area, and subcortical volume.

RESULTS

Data from 8862 ABCD participants aged 9 to 10 years were analyzed. The mean (SD) age was 119.1 (7.5) months; there were 4243 girls (47.9%) and 4619 boys (52.1%). Data on race or ethnicity were available for 8857 of 8862 participants: 173 (2.0%) were Asian, 1099 (12.4%) were Black or African American, 1688 (19.1%) were Hispanic, 4967 (56.1%) were White, and 930 (10.5%) reported multiple races or ethnicities. Using 10-fold, within-sample split-half replication, we found that neighborhood disadvantage was associated with lower cortical thickness in the following brain regions (η2 = 0.004-0.009): cuneus (B [SE] = -0.099 [0.013]; P < .001), lateral occipital (B [SE] = -0.088 [0.011]; P < .001), lateral orbitofrontal (B [SE] = -0.072 [0.012]; P < .001), lingual (B [SE] = -0.104 [0.012]; P < .001), paracentral (B [SE] = -0.086 [0.012]; P < .001), pericalcarine (B [SE] = -0.077 [0.012]; P < .001), postcentral (B [SE] = -0.069 [0.012]; P < .001), precentral (B [SE] = -0.059 [0.011]; P < .001), rostral middle frontal (B [SE] = -0.076 [0.011]; P < .001), and superior parietal (B [SE] = -0.060 [0.011]; P < .001). Exploratory analyses showed that the associations of low educational attainment or neighborhood disadvantage and low cortical thickness were attenuated in the presence of a high income-to-needs ratio (η2 = 0.003-0.007).

CONCLUSIONS AND RELEVANCE

The findings of this cross-sectional study suggest that different SES indicators have distinct associations with children's brain structure. A high income-to-needs ratio may play a protective role in the context of neighborhood disadvantage and low parent or caregiver educational attainment. This study highlights the importance of considering the joint associations of different SES indicators in future work.