Inflammatory Challenge and Fear Extinction: A Model to Enhance Understanding of Posttraumatic Stress Disorder

What this Trial Is About

Researchers are investigating how short-term changes in the immune system affect how people process information and experience fear, particularly in those with and without posttraumatic stress disorder (PTSD). This study aims to understand whether receiving a typhoid vaccine leads to different responses compared to receiving a placebo saline injection, focusing on how inflammation might influence fear responses. The research also explores differences between men and women, given that PTSD affects women more frequently and inflammation may impact fear responses differently by sex. Participants will be randomly assigned to receive either a typhoid vaccine or a saline placebo injection. The vaccine contains purified components designed to provoke an immune response. The study involves initial physiological testing of fear responses, followed by vaccination or placebo administration three days later, and additional testing one week after the injection. Measures of inflammation will be collected at several points, including before and after the vaccine or placebo. During the study, participants will attend four appointments where their physiological reactions to sounds will be recorded, and they will complete questionnaires and psychological tests. Researchers will measure skin conductance responses, heart rate, and eyeblink activity at baseline, 4.5 hours, and one week after injection to assess fear responses. These assessments will help clarify the role of inflammation in fear processing and PTSD. The total study duration includes these multiple visits and follow-up measures to monitor safety and response changes.

Inflammatory Challenge and Fear