Study: Doxycycline for PTSD Treatment?

APRIL 05, 2017
Jennifer Barrett, Assistant Editor

Doxycycline disrupts the formation of negative associations in the brain that contribute to post-traumatic stress disorder (PTSD), a new study published in Molecular Psychiatry concluded. Fear responses in participants taking the antibiotic were shown to be reduced, indicating that the drug can suppress fear memory and potentially prevent the development of overactive fear memory.1  
The study was conducted as a placebo-controlled, double-blind, randomized controlled trial with 76 healthy participants. In the first session, participants were given either doxycycline or a placebo and were taught to associate a certain color with an electric shock. A week later, the participants were shown the same colors accompanied with a loud sound, but no shock. The researchers measured their fear responses.
The researchers measured the participants’ fear responses by tracking their eye blinks. The response was calculated by subtracting the baseline startle response from the response to the sound when the “bad” color was shown.
Participants who had taken doxycycline experienced a fear response 60% lower than those who had a placebo. The results indicate that doxycycline can reduce fear memory response in individuals, which can play a potentially significant role in PTSD, which is characterized by overactive fear memory.
“We have demonstrated a proof-of-principle for an entirely new treatment strategy for PTSD,” Professor Dominik Bach, MD, PhD, and lead author, said in a press release about the study.2 “To treat such diseases, we already have clinically approved drugs that block these enzymes, including the antibiotic doxycycline, so we wanted to see if they could help to prevent fear memories from forming in the brain.”
Although Bach acknowledged that using drugs to prevent PTSD would be challenging in a real-world setting, he noted that growing evidence supports the reconsolidation of individual’s memories and associations after an event, and that further research into doxycycline’s effects on reconsolidation of fear memories could have potential clinical benefits.  
The researchers concluded that the findings could hold direct therapeutic implications, indicating that tetracycline antibiotics could be used for primary prevention of fear memory acquisition in individuals.
The research was conducted by UCL and the University of Zurich.
  1. Bach DR, Tzovara A, Vunder J. Blocking human fear memory with the matrix metalloproteinase inhibitor doxycycline. Molecular Psychiatry. 2017; doi: 10.1038/MP.2017.65.