Antibiotics Could Help Fight PTSD

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Over the past several decades, a lot of work and scientific effort has been dedicated to finding new methods of treating post-traumatic stress disorder, an extreme anxiety disorder that triggers severe responses to reminders of past trauma. PTSD has been observed among veterans, sexual assault survivors, survivors of physical and emotional abuse, survivors of natural disasters, and those who have been subjected to a wide array of other circumstances; the lasting impact of trauma can be found in many different lives. However, a new discovery may shift the way in which we think about, and treat, PSTD — and also make treating survivors a lot cheaper.

Currently, PTSD treatments are pretty extensive and long-term; most of them involve "exposure" therapies, in which people are slowly introduced to elements of trauma until they become familiar with them, recognize that they're not threatening to them, and no longer react with such extremity to their triggers. (This is one of the things that makes PTSD so damaging: its potential to rear up in situations that vaguely resemble the original trauma, or even at the touch of a single sense, like a scent or a sound.) Medical options are also currently being tested, including ketamine (which, a 2014 study found, looks pretty promising), but the new medication comes from an area that's perhaps a bit unexpected: the world of antibiotics.

Antibiotics Can Change The Physical Parts Of Our Brains Where Traumatic Memories Are Stored

What on earth do antibiotics have to do with PTSD? Well, it's all a matter of perspective. Most of us view problems of the brain as separate from the physical side of the body. But the fact is that there is a strong physical aspect to mental health: yogurt that helps probiotic levels in the gut, for instance, has been shown to improve depression in some studies due to a connection between the digestive system and the brain. And it's the physical part of our memory, in particular, that's the focus of this new PTSD theory.

We know a bit about the neurobiology of how memories are formed, though there's still a lot to be uncovered. In 2012, some scientists proposed that memory might involve "three physiologic components" in the brain: "namely, the neuron (individual and circuit), the surrounding neural extracellular matrix, and the various trace metals distributed within the matrix." The extracellular matrix around your neurons is pretty amazing; it makes up around 20 percent of the brain, is unique in its composition, and forms a series of lattices called "nets." And this bit is why antibiotics might be able to help with PTSD.

One enzyme from these lattices, matrix metalloprotenaise 9 (MM9 to its friends), has been implicated in how we form spatial memories, for instance, and seems to be required for long-term memory. Which is what ties it to PTSD — part of the horror of PTSD is that specific traumatic memories make sufferers go into immediate fight-or-flight mode, rather than experiencing them with the feelings one would normal apply to any negative memory. In short, PTSD can make sufferers feel like their past trauma is reoccurring in the present — and it looks as if MM9 can be hijacked via antibiotics, and used to make people "relearn" how particular threatening stimuli and memories are processed.

How Antibiotics Helps Rewire PTSD Brains

According to the scientists behind the new study (who come from both University College London and the University of Zurich), the important thing about MM9 is that it seems to be inhibited in the brain's lattices by a common antibiotic: doxycycline. It's pretty widely available as a common treatment for bacterial infections like UTIs (and is a lifesaver for people like me, who are violently allergic to penicillin). Doxycycline blocks MM9's formation — and given that MM9 seems to be pretty necessary for memories, that should have an after-effect on how we remember events.

The British and Swiss scientists set out to test the idea with 76 non-PTSD volunteers; they divided them up into groups, then gave one group doxycycline. Both groups were then "taught" to associate a certain color with getting an electric shock. They were using something Pavlov taught us a long time ago: our associative memories are powerful things.

When they brought back the groups a week later and repeated the experiment, with no drugs and using loud noises instead of electric shocks, they discovered that the group that had a dose of doxycycline at the very start showed 60 percent less fear response.

Both groups remembered the experiences in the same way, but the ones who'd had a dose of the antibiotic were much less likely to have a rapid fear response to the shocks. The reduction in "threat memory" was so good, the scientists think, because the antibiotic fiddled with the subjects' MM9 levels, meaning that the traumatizing part of the memory of being shocked didn't really implant itself properly.

The research seems to imply that, theoretically, people who are about to enter traumatic situations (like a person in the armed forces or emergency service personnel) could take doxycycline beforehand and be less likely to come out of the situation with post-traumatic stress.

And it wouldn't only work as a preventative — the scientists who conducted the study also suggest that it could help treat PTSD after traumatic situations have already occurred. "There is growing evidence," they said in a press release, "that people's memories and associations can be changed after the event when they experience or imagine similar situations. This is called 'reconsolidation,' and we now plan to test the effect of doxycycline on reconsolidation of fear memories. If this is successful, we would hope to apply the technique to more clinically realistic models of PTSD within a few years."

Doxycycline has a lot of advantages, too. It's already legal, it's cheap, and it's widely available. There's still a way to go before it can be applied properly to the problem of PTSD in the real world. But it's exciting to know that we may be on step closer to helping PTSD sufferers live their lives with more peace and less pain.