Longitudinal change in resting-state functional brain connectivity associated with secondary sexual characteristics between ages 11 and 13 years.

Pubertal maturation drives brain development, yet longitudinal evidence linking it to resting-state functional connectivity (rs-FC) in early adolescence remains limited, and adolescent mental-health trajectories differ by sex, motivating sex-specific analyses. In a general-population cohort (255 adolescents scanned at Time 1; 68 girls and 70 boys with analysable two-wave data), we examined longitudinal change in rs-FC between ages ∼11.5 and ∼13.6 years, separately by sex. Whole-brain analyses were applied without predefined regions of interest, using principal component analysis (PCA) as a data-driven screen and network-based statistics (NBS) to localize subnetworks associated with pubertal stage (Tanner stage). Among girls, Tanner breast stage at Time 2 was significantly associated with the fingerprint stability (within-individual similarity) of whole-brain rs-FC. NBS identified a subnetwork positively associated with Tanner breast stage, linking the thalamus to visual, auditory, and motor areas and the prefrontal operculum to frontoparietal association areas, with the PCA screen converging on thalamic involvement. No comparable associations were observed in boys. These findings suggest that the level of pubertal maturation is associated with the longitudinal stability of large-scale brain networks in girls.