Can a Common Antibiotic Prevent or Treat PTSD?

A common antibiotic, doxycycline, may prove useful in the treatment and/or prevention of Post- Traumatic stress disorder (PTSD), according to research by British and Swiss scientists.

PTSD is caused by an overactive fear memory and includes a broad range of psychological symptoms that can develop after someone goes through a traumatic event. This medication can disrupt the formation of negative thoughts and fears in the brain.

In a specially designed trial involving seventy-six (76) healthy volunteers, participants were given either doxycycline or a placebo and placed in front of a computer. The screen would flash either blue or red, and one of the colors was associated with a 50 percent chance of receiving a painful electric shock. After 160 flashes with colors in random order, participants learnt to associate the ‘bad’ color with the shock.

Those who were on doxycycline had a 60 percent lower fear response than those who were not.

In a follow-up experiment one week later, without any medication, the volunteers repeated the screen flashes, but this time there were no electric shocks, but a loud sound played after either color was shown.

Fear responses were measured by tracking eye blinks, as this is an instinctive response to sudden threats. The fear memory was calculated by subtracting the baseline startle response, to the sound on the ‘good’ color, from the response to the sound when the ‘bad’ color was showing.

The participants may not forget that they received a shock when the screen was red, but they “forget” to be instinctively scared when they next see a red screen.

Further experiments will explore doxycycline’s potential effects in a phenomenon called “reconsolidation” of fear memories. This is an approach to helping people with PTSD in which memories and associations can be changed after an event when the patient experiences or imagines similar situations.

The study was published in Molecular Psychiatry.