Brain network features predating early alcohol initiation in adolescence.

Emerging evidence suggests regional neuroanatomical variability may be predictive of early alcohol use (before age 15). However, the relationship between whole-brain network organization and early alcohol initiation remains unknown. Using data from the Adolescent Brain Cognitive Development (ABCD) study, we conducted a structural covariance network (SCN) analysis to examine brain network features preceding early alcohol initiation. Structural MRI data collected at baseline (ages 9-10) were used to generate SCNs based on regional cortical thickness measurements. Early alcohol initiation was defined as consuming a full drink between baseline and 4-year follow-up ( ≤ age 15). Participants who reported a full drink of alcohol at baseline, did not participate in the 4-year follow-up, or did not meet imaging quality control criteria were excluded. The remaining participants were compared to a subsample matched at a 1:1 ratio (n = 160 per group). SCN properties, including network segregation (modularity, clustering coefficient), integration (characteristic path length, global efficiency), and resilience (degree assortativity), were compared between groups. While no differences in regional cortical thickness between groups were identified, early initiators demonstrated lower segregation and higher integration compared to non-initiators. These findings suggest that cortical thickness network topology at ages 9-10 may serve as a neuroanatomical risk marker for early adolescent alcohol initiation, independent of prior alcohol exposure, sociodemographic differences, and regional neuroanatomical variability.