Psychedelics can reverse neuroimmune interactions that boost fear

Psychedelics including MDMA and psilocybin may reduce stress-related fear by reversing neuroimmune interactions. Researchers at Brigham and Women's Hospital found that immune signals can drive fear responses through communication between immune and brain cells in the amygdala, particularly during chronic stress. Increased immune-brain crosstalk was linked to elevated inflammatory signaling and activation of fear-promoting amygdala neurons. In stressed mouse models, treatment with psilocybin or MDMA prevented monocytes from accumulating in the brain meninges and lowered fear behaviors. Similar stress response patterns were reported in human brain cell signals and gene expression datasets from patients with major depressive disorder, suggesting a potential shared mechanism. Results were published in Nature, with follow-up planned to test longer-term effects in depression and inflammatory disease contexts.