Researchers have discovered a promising avenue for the treatment of post traumatic stress disorder (PTSD) and other anxiety disorders. In a preclinical trial in mice, researchers found that drugs called histone deacetylase inhibitors (HDACis) can enhance the brain’s ability to permanently replace old traumatic memories with new memories.
For the study, researchers at Massachusetts Institute of Technology used a protocol for studying fear responses associated with traumatic memories. In the first phase, researchers exposed mice to a tone followed by an electrical footshock. Once the mice learned to associate the two events, they began to freeze in fear when hearing the tone by itself. Then, using extinction protocol, which is similar to exposure-based therapy commonly used for PTSD, researchers presented the tone repeatedly without the shock to test if the mice could unlearn the association between these two events and would stop freezing in response to the tone. This method was successful for mice that were exposed to the tone-shock just one day earlier, but not for mice that originally formed the tramatic memory one month earlier.
Then, researchers tested whether HDACis could replace old traumatic memories with new memories. "Collectively, our findings suggest that exposure-based therapy alone does not effectively weaken traumatic memories that were formed a long time ago, but that HDACis can be combined with exposure-based therapy to substantially improve treatment for the most enduring traumatic memories," senior study author Li-Huei Tsai was quoted as saying.