Single stressful event may lead to trauma: Indian scientists

A single instance of severe stress can lead to delayed and long-term psychological trauma, according to a new study by Indian scientists that may lead to new treatments for post-traumatic stress disorder (PTSD).
The study by National Centre for Biological Sciences (NCBS) and the Institute for Stem Cell Biology and Regenerative Medicine (inStem) in Bangalore pinpoints key molecular and physiological processes that could be driving changes in brain architecture.
Researchers have shown that a single stressful incident can lead to increased electrical activity in a brain region known as the amygdala.
This activity sets in late, occurring ten days after a single stressful episode and is dependent on a molecule known as the N-Methyl-D-Aspartate Receptor (NMDA-R), an ion channel protein on nerve cells known to be crucial for memory functions.

The amygdala is a small, almond-shaped groups of nerve cells that is located deep within the temporal lobe of the brain.
This region of the brain is known to play key roles in emotional reactions, memory and making decisions.

Changes in the amygdala are linked to the development of post-traumatic stress disorder (PTSD), a mental condition that develops in a delayed fashion after a harrowing experience.
Previously, the same group had shown that a single instance of acute stress had no immediate effects on the amygdala of rats.
However, ten days later, these animals began to show increased anxiety and delayed changes in the architecture of their brains, especially the amygdala.

"We showed that our study system is applicable to PTSD. This delayed effect after a single episode of stress was reminiscent of what happens in PTSD patients," said Sumantra Chattarji from NCBS.
"We know that the amygdala is hyperactive in PTSD patients. But no one knows as of now, what is going on in there," said Chattarji.
Investigations showed major changes in the microscopic structure of the nerve cells in the amygdala.
Stress seems to have caused the formation of new nerve connections called synapses in this region of the brain.
However, until now, the physiological effects of these new connections were unknown.

In their recent study, Chattarji's team has established that the new nerve connections in the amygdala lead to heightened electrical activity in this region of the brain.
"Most studies on stress are done on a chronic stress paradigm with repeated stress, or with a single stress episode where changes are looked at immediately afterwards - like a day after the stress," said Farhana Yasmin from NCBS.
"Our work is unique in that we show a reaction to a single instance of stress but at a delayed time point," she said.
The study appears in the journal Physiological Reports.