Turns out keeping your cool really is all in your head—scientists now pinpoint those most susceptible to stress as having too much of a chemical in a region of the brain that regulates reward signals, Reuters reports. The discovery could shed light on treatments for PTSD and depression, which are bound up with the same neurochemical produced in stressful situations.
Researchers exposed mice to a bully mouse, and then monitored the way they responded to the encounter over a period of time. Those still shaken up after a month showed disproportionately high levels of BDNF, a chemical associated with poor coping skills, found in depressed human brains. "It seems to be a signature of vulnerability to depression," said one psychologist.