Dude, Where's my Trauma? Marijuana Could Treat PTSD

Posted by Maia Szalavitz Wednesday, November 4, 2009 at 5:15 pm

11 Comments • Trackback (6) • Marijuana Stress, cannabis, Marijuana, medical marijuana, memory, post traumatic stress disorder, ptsd, Stress

Many millions have been made in Hollywood by lampooning the acute effects of marijuana on memory—but Israeli researchers suggest that they might one day be harnessed to prevent or treat post-traumatic stress disorder (PTSD). And today's election results bringing medical marijuana dispensaries to yet another state suggest that day might be sooner than ever.

A new study—published in the Journal of Neuroscience—found that a synthetic drug that acts like one of the active components in marijuana (THC) can prevent stress-induced enhancement of fear memories in rats. PTSD is basically a syndrome in which fear-filled memories intrude on daily life and sleep—so preventing stress from strengthening memories of fear could potentially prevent or treat it.

In the study, the rats were trained to fear a dark region of a cage where they received electric shocks. Though rats normally prefer dark places, they learned to stay in the light and avoid the now-scary dark area. When researchers stopped giving shocks in the dark region, rats slowly learned that it was safe again and began to return to it. The researchers measured how long this took.

During the next experiment on a new group of rats, the experience was made more stressful. Now, rats were placed on an elevated grid after receiving the shock. Rats-- and most other animals, including many humans--tend to avoid walking over elevated grids if they can, and find being forced to do so distressing. As expected, the researchers found that it took longer for these rats to learn that the dark region was safe again.

Here's where the marijuana comes in. Researchers trained another group of rats with the grid and the shock. But when they injected the synthetic THC-like compound into a brain region associated with fear, these rats learned as quickly to return to their preferred dark spot as those which had only experienced the more minor stress.

In other words, the marijuana-like compound had made extreme stress more like ordinary stress—and this could also be seen in terms of reductions in a key stress hormone in their brains.

Importantly, it didn't matter if the rats were given the drug before or after they experienced the stress. This suggests that this drug might work either before or after someone has suffered a traumatic event. It also shows that the drug doesn't erase memory—instead, it softens it and makes traumatic memory more like ordinary memory.

Of course, we can't inject drugs into the brains of humans and it is not known if ordinary marijuana or the FDA-approved pill that contains THC would have this effect. But this research suggests that it should be studied, because there are currently very few effective treatments for PTSD and research shows that between 10 and 30% of people exposed to trauma will develop PTSD without intervention.