A new study suggests that fear and the immune system are connected in previously unknown ways. Researchers at Mass General Brigham found that the immune system can influence stress and fear behaviors by changing how brain cells communicate.
The investigators further showed that psychedelic treatments could target these neuroimmune interactions and reduce stress-induced fear in preclinical models and found similar results in human tissue samples.
Results are published in Nature.
“Our study underscores how psychedelics can do more than just change perception; they can help dial down inflammation and reset brain-immune interactions,” said corresponding author Michael Wheeler, PhD, of the Gene Lay Institute of Immunology and Inflammation as well as the Ann Romney Center for Neurologic Diseases at Brigham and Women’s Hospital (BWH), a founding member of the Mass General Brigham healthcare system.
“This could reshape how we think about treatment for inflammatory disorders and conditions like anxiety and depression.”
Prior research has shown immune signaling can drive the development of neuropsychiatric diseases such as major depressive disorder (MDD). However, the ways that specific immune mechanisms can also affect behaviors due to chronic stress or MDD remained unclear.
Using a mouse model of chronic stress, the researchers determined that increased crosstalk between cells in the amygdala, or the brain’s fear center, boosted fear behaviors, elevated inflammatory signaling, and activated fear-promoting amygdala neurons.
Furthermore, inflammatory immune cells called monocytes migrated from other parts of the body to the brain meninges during chronic stress. The research team demonstrated that artificially manipulating these cells impacted fear behaviors.
Treating stressed mice with psilocybin and MDMA prevented monocytes from accumulating in the brain and lowered fear behaviors.
Hellbound and Down 