Drug may Help PTSD Patients Replace Traumatic Memories with New Ones

Researchers from the Massachusetts Institute of Technology and colleagues have recently discovered a new drug that may be able to help those suffering from post-traumatic stress disorder and other anxiety issues. The drug, known as histone deacetylase inhibitors (HDACis), carries the ability replace traumatic memories with new ones. 

"Psychotherapy is often used for treating PTSD, but it doesn't always work, especially when the traumatic events occurred many years earlier," said senior study author Li-Huei Tsai of the Massachusetts Institute of Technology, via a press release. "This study provides a mechanism explaining why old memories are difficult to extinguish and shows that HDACis can facilitate psychotherapy to treat anxiety disorders such as PTSD."

Common treatments for anxiety disorders often involve exposure-based therapies that use fear-evoking techniques in a safe environment. As the process reactivates the hurtful memories, it also provides the patient with the ability to disrupt original memory and replace it with something new. However, until now, it was not clear if this could be effective for older traumatic memories.

For the study, Tsai and study authors exposed mice to a tone followed by an electrical footshock. Once the mice learned to connect the two events, they began to freeze in fear upon hearing the tone even if the shock was not received. Afterwards, the researchers repeatedly presented the tone without the shock to see if the mice could unlearn the fear response. The study showed that this extinction protocol was successful for mice who were exposed to the tone-shock pairing just one day earlier, but not those who originally formed the traumatic memory one month before.

"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," Tsai concludes.

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More information regarding the study can be found via the journal Cell.