Neurodevelopmental and behavioral correlates of household structure independent of socioeconomic status.

Introduction: Parental socioeconomic status (SES) is associated with children's brain development and mental health but does not fully capture variation in caregiving environments. Household structure, including the number of caregivers in the home, may also shape children's experiences through differences in supervision, support, and daily demands. Because household structure and SES are closely linked, it remains unclear whether differences in child outcomes reflect economic conditions, caregiving context, or both. This study examined whether household structure is associated with psychopathology symptoms and brain structure after accounting for SES. Methods: Participants included 7890 children (ages 9-10) from the Adolescent Brain Cognitive Development Study living in households with one or two caregivers. Associations between household structure, psychopathology, and gray matter volume were examined while controlling for age, sex, site, family income, and parental education. Sensitivity analyses included additional caregiving and mental health factors. Mediation analyses tested whether total cortical and subcortical volumes were associated with the relationship between household structure and psychopathology. For all analyses, multiple comparisons were controlled using false discovery rate correction. Results: Households with two caregivers had, on average, higher income and parental education. After adjustment for SES and covariates, differences were observed in externalizing behaviors and attention-related symptoms. Small but widespread differences in regional brain volumes were also observed and remained robust in sensitivity analyses. Total cortical and subcortical volumes were associated with both household structure and behavioral outcomes, with small but significant indirect effects indicating significant mediation. Discussion: Although effect sizes were small, findings suggest that aspects of caregiving context captured by household structure are associated with child development above and beyond SES. Brain structure differences may represent one pathway linking caregiving context to behavioral outcomes, though effects were modest. Further work is needed to identify specific, modifiable processes underlying these associations.