Complex trauma doesn’t just leave a psychological imprint — it reshapes the architecture and functioning of the brain. Research consistently shows three key regions are most impacted: The Amygdala Often becomes hyper-reactive, scanning constantly for threat. In CPTSD, this can look like chronic hypervigilance, startle responses, emotional overwhelm, and difficulty distinguishing present cues from past danger. The Hippocampus Can become underactive or structurally altered after long-term trauma.