Posttraumatic stress disorder (PTSD) arises after experiencing traumatic events, however not every people experiencing trauma will develop it. Our co-president and her group looked into factors that make certain individuals more susceptible. This new study reveals a link between glucocorticoids, hormones released by our body in response to stress, and the development of PTSD. The researchers discovered that a blunted responsiveness to glucocorticoids led to a “correlated multi-trait response” that includes impaired fear extinction (in males), reduced hippocampal volume, and rapid-eye movement sleep disturbances. In addition, they treated the rats with the equivalent of human cognitive and behavioral therapy to reduce their learned fears. After that, they gave the rats corticosterone. As a result, both excessive fear and disturbances in rapid-eye movement sleep receded and the increased levels of the stress-related neurotransmitter norepinephrine in the brain returned to normal. These results can bring key contributions in the prevention and targeted treatment of PTSD.