Stress Causes Lasting Brain Changes: ‘The research team… looked at what happened to mouse brain cells and to live mice following brief exposure to different types of stress. Their findings appear in the Jan. 18 issue of Science.

They found that within minutes of exposure, brain nerve cells, or neurons, became hypersensitive. And the change lasted for several weeks — long after the stress was gone. This is in keeping with victims of posttraumatic stress, who despite time and distance from the original trauma remain physically, mentally, and emotionally agitated.’ WebMD