Better Understanding PTSDs

A team of neuroscientists has found that stress enhances ordinary, unrelated memories and therefore it could increase the pathological effects of post-traumatic stress disorder (PTSD) and other anxiety disorders.

They carried out their study on rats, hoping that this could help them understand the disorder a little better and maybe make another step towards addressing it, as well as the other related afflictions.

A very frequent phenomenon in PTSD is the negative association between inoffensive stimuli and negative memories, but the exact role that stress plays in all this was rather unclear.

So, André Fenton, the study's lead author and a professor at New York University's Center for Neural Science, along with Karel Ježek of the Czech Republic's Academy of Sciences, Benjamin Lee and Eduard Kelemen of State University of New York (SUNY) Downstate and Katharine McCarthy and Bruce McEwen of Rockefeller University, wanted to find out the impact that stress has on these disorders.

They conducted several experiments using laboratory rats, and taught them to make the difference between left and right in a T-shaped maze.

A day after, the researchers used a very common technique to induce stress to rats – they placed some of them in a bucket of water in which they had to swim, and others in shallow water, where swimming was not necessary.

Once the experiment was over, the rats were placed again in the maze and tasked to navigate, and the researchers concluded that the rats who had undergone the stressful swim remembered much better which way to turn in the T-maze than those placed in shallow water.

To exclude any bias from their findings, the researchers carried out other additional experiments, that ruled out that learning the maze itself was a source of stress and showed a clear connection between the stress caused by the swim and changes in the memories of navigating the maze, even though the changed memories were unrelated to the stressful experience.

Fenton, who directed the studies while he was a Research Scientist in the Czech Republic and an associate professor of physiology and pharmacology at SUNY Downstate, said that the “results show that stress can activate memory, even if that memory is unrelated to the stressful experience.

“Additional investigations into the effects of stress on memories could shed light on PTSD and other stress-related mood disorders.”

The results appear in the journal PLoS Biology.