Lasting Consequences of Early Deprivation and Foster Care Intervention on Early Adulthood Cortical Structure and ADHD Symptoms

Early psychosocial deprivation is associated with atypical cortical development and elevated rates of ADHD, yet little is known about how these effects extend into early adulthood. In this study, we examined cortical structure at ages 16 and 21 within the Bucharest Early Intervention Project (BEIP), the only longitudinal randomized controlled trial of foster care as an alternative to institutional rearing. Analyses compared individuals with a history of institutional rearing (EIG) to never-institutionalized peers (NIG) and, within the ever-institutionalized group, those randomized to foster care (FCG) versus care-as-usual (CAUG). Participants underwent structural MRI scans at ages 16 and 21. Using this data, we evaluated whether early institutionalization alters cortical maturation from adolescence to adulthood and whether ADHD symptoms, which are commonly associated with early deprivation, interact with deprivation group to predict cortical structure. Whole-brain vertex-wise analyses of cortical thickness and surface area were conducted in FreeSurfer using cross-sectional and longitudinal models. Longitudinal analyses of change from ages 16 to 21 showed that children in the EIG exhibited greater cortical thinning in the right middle temporal cortex and greater surface area reduction in the left cuneus relative to the NIG. However, no cross-sectional group differences were detected at age 21. In addition, among children with a history of institutionalization, ADHD symptoms at age 16 did not interact with randomized caregiving group to predict cortical structure in early adulthood. These findings suggest that early deprivation shapes the timing and trajectory of cortical maturation rather than producing static structural differences in adulthood, highlighting the enduring impact of early caregiving environments on brain development.