Sustained breastfeeding associations with brain structure and cognition from late childhood to early adolescence

While breastfeeding benefits early child neurocognition, its influences into adolescence, a period of intense brain remodeling and heightened mental health risk, remain unclear. Breastfeeding and neurocognitive longitudinal associations were explored over a two-year period in the Adolescent Brain Cognitive Development (ABCD) Study® (nbaseline = 5098, ages 9-10, 49% female; nfollow-up = 3810, ages 11-12, 48% female). Breastfeeding duration was reported as never breastfed (15.8%), 1-6 months (34.6%), 7-12 months (26.4%), and >12 months (23.1%). MRI-derived estimates of cortical thickness, surface area, and cortical myelin were calculated across 148 brain regions alongside fluid cognition measures. Linear mixed-effects models tested the influence of breastfeeding duration and its interaction with age on neurocognitive outcomes. Significant cortical thickness and surface area associations were explored for cortical myelin differences. Parallel mediation analyses examined whether cortical features mediated the breastfeeding-fluid cognition relationship. Breastfeeding duration was positively associated with cortical thickness (31 regions), surface area (45 regions), and fluid cognition (all p values < 0.05), and with greater cortical myelin in four regions and increases by follow-up in 12 regions (all p values < 0.05). Surface area mediated the breastfeeding-fluid cognition link (β = 0.008, CIboot95% = 0.005, 0.012). These findings emphasize the importance of extending breastfeeding practices for optimal adolescent neurocognition. Does breastfeeding influence neurocognition during early adolescence, and does it impact neurocognitive development at this stage? In this longitudinal study, breastfeeding demonstrated dose-dependent, lasting positive influences on neurocognition that remained stable over a 2-year period spanning late childhood to early adolescence. Specifically, individuals who were breastfed longer showed increased cortical thickness, surface area, cortical myelin, and fluid cognition, predictors of positive outcomes in later life, including physical and mental health. Our findings highlight the importance of breastfeeding and support its extended practice for optimal neurodevelopment and potential late-life benefits.