Prospective study of polygenic risk, protective factors, and incident depression following combat deployment in US Army soldiers.

Polygenic risk was associated with new-onset MDD in deployed soldiers. However, unit cohesion - an index of perceived support and morale - was protective against incident MDD even among those at highest genetic risk, and may represent a potent target for promoting resilience in vulnerable soldiers. Findings illustrate the value of combining genomic and environmental data in a prospective design to identify robust protective factors for mental health.