Psychedelic tryptamines like psilocybin show promise for treating major depressive disorder (MDD) after a single dose, with two Phase III trials receiving FDA Breakthrough Therapy status. Beyond MDD and substance use disorders, rodent studies suggest psychedelics may also help treat or prevent brain injury and neurodegenerative diseases such as Alzheimer's Disease. Preclinical evidence indicates they can induce neuroplasticity, synaptogenesis, and neural progenitor cell proliferation, and act as immunomodulators by reducing proinflammatory biomarkers like IL-1β, IL-6, and TNF-α. The exact molecular mechanisms and cellular interactions underlying these therapeutic effects remain unknown.
Two classic psychedelics, DMT and psilocin, can alter the behavior of microglia—the brain's immune cells—by reducing levels of immune response markers (TLR4, p65, CD80) and increasing the neuroprotective receptor TREM2. Psilocin also protected neurons in a lab model by reducing microglial phagocytosis. The findings suggest that psychedelics or their analogs may be candidates for treating neurological disorders where inflammation and microglia play a key role.