The gut-brain axis (GBA) is a complex, bidirectional communication network critical to integrating central nervous system functions with gastrointestinal (GI) health. This review examines how disruptions to the GBA during the critical early-life developmental window – a period of rapid neurogenesis and microbial colonization – contribute to long-term neurocognitive and psychiatric vulnerabilities. Evidence from animal models demonstrates that early-life stress, antibiotics, and infection induce