The molecular cause of severe depression condition has been identified by researchers who have developed a method of preventing it by injecting calming drugs.
The researchers discovered that brain becomes overly stimulated after a traumatic event causes an ongoing, frenzied interaction between two brain proteins long after they should have disengaged.
"It's like they keep dancing even after the music stops," explained principal investigator Jelena Radulovic, of Northwestern University Feinberg School of Medicine.
When newly developed research drugs MPEP and MTEP were injected into the hippocampus, the calming drugs ended 'the dance'.
"We were able to stop the development of exaggerated fear with a simple, single drug treatment and found the window of time we have to intervene. Five hours is a huge window to prevent this serious disorder," Radulovic said.
"People with this syndrome feel danger in everything that surrounds them," she noted.
The study was conducted in mice. The scientists checked their response to fearful happenings and found that after two stressful experiences these mice froze in fear 80 to 90 percent of the time instead of normal 50 percent.
The animals' exaggerated chronic fear response continued for at least one month and resembles post-traumatic stress disorder in humans, Radulovic said.
In the following part of the study, Radulovic, along with a postdoctoral fellow Natalie Tronson, repeated the two stressful experiences with the mice but then injected them with MPEP and MTEP five hours after the immobilization.
This time the mice did not develop the exaggerated fear response and froze for only 50 percent of the time.
"The mice's fear responses were completely normal. Their memories of the stressful event didn't trigger the extreme responses anymore. This means we could have a prevention approach for humans exposed to acute, severe stressful events," concluded Radulovic.
The study appears in the journal Biological Psychiatry.