Could Pot Help Veterans with PTSD? Brain Scientists Say Maybe
NPR. December 24, 2013
Veterans who smoke marijuana to cope with post-traumatic stress disorder may be onto something. There’s growing evidence that pot can affect brain circuits involved in PTSD.
Experiments in animals show that tetrahydrocannabinol, the chemical that gives marijuana its feel-good qualities, acts on a system in the brain that is “critical for fear and anxiety modulation,” says Andrew Holmes, a researcher at the National Institute on Alcohol Abuse and Alcoholism.
The use of marijuana for PTSD has gained national attention in the past few years as thousands of traumatized veterans who fought in Iraq and Afghanistan have asked the federal government to give them access to the drug. Also, Maine and a handful of other states have passed laws giving people with PTSD access to medical marijuana.
For decades, researchers have suspected that marijuana might help people with PTSD by quieting an overactive fear system. But they didn’t understand how this might work until 2002, when scientists in Germany published a mouse study showing that the brain uses chemicals called cannabinoids to modulate the fear system, Ressler says.
There are two common sources of cannabinoids:
- One is the brain itself, which uses the chemicals to regulate a variety of brain cells.
- The other common source is Cannabis sativa, the marijuana plant.
So in recent years, researchers have done lots of experiments that involved treating traumatized mice with the active ingredient in pot, tetrahydrocannabinol (THC), Ressler says. And in general, he says, the mice who get THC look “less anxious, more calm, you know, many of the things that you might imagine.”
Problems with Pot
Unfortunately, THC’s effect on fear doesn’t seem to last, Ressler says, because prolonged exposure seems to make brain cells less sensitive to the chemical.
Another downside to using marijuana for PTSD is side effects, says Andrew Holmes at the National Institute on Alcohol Abuse and Alcoholism. “You may indeed get a reduction in anxiety,” Holmes says. “But you’re also going to get all of these unwanted effects,” including short-term memory loss, increased appetite and impaired motor skills.
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