Aim:
Chronic war-related stress reshapes large-scale brain coordination by shifting functional coupling from posterior association hubs toward anterior control and salience areas. Understanding whether such reorganization differs by sex may provide important insight into differential vulnerability under prolonged stress exposure.

Material and methods:
Fifty-three students of Taras Shevchenko National University of Kyiv (aged 18–24) voluntarily participated in the study. Pre-war groups (n = 24, nfem = 15) were examined between 2010 and 2012, before the onset of Russia’s hybrid and full-scale invasion and the COVID-19 pandemic. War groups (n = 29, nfem = 18) were assessed during the ongoing full-scale invasion (2022–2024). EEG recordings were obtained at rest and during cognitive load induced by a mental arithmetic task. Magnitude-squared coherence was analyzed in θ1 (3.9–4.9 Hz), θ2 (5–6 Hz), β1 (13–20 Hz), and β2 (20–30 Hz) bands.

Results:
Pre-war maps showed posterior-dominant coupling with robust P3–P4 and O1–O2 homotopy and a preserved Fz–Cz–Pz axis. Men additionally exhibited stronger C3–C4 and midline integration, whereas women showed a right-posterior bias and weaker fronto-posterior coupling. During the war, men demonstrated strengthened fronto-temporal coupling and accentuated dorsal midline links, while women displayed diffuse θ reinforcement over right temporoparietal and posterior midline regions, emergent cross-hemispheric fronto-temporal links, and persistently attenuated long-range coupling. In β bands, posterior homotopy weakened in both sexes, with frontal strengthening more pronounced in women.

Conclusions:
Chronic war stress drives posterior-to-anterior reweighting of coherence, supporting reactivity through salience/control hubs at the expense of efficiency. Women’s weaker long-range fronto-posterior coordination suggests heightened vulnerability and points toward sex-specific intervention strategies.