Study Links PTSD and Brain Receptors Activated by Marijuana

A new study finds a connection between post-traumatic stress disorder (PTSD) and the number of cannabinoid receptors in the brain. These receptors, called CB1, are activated when a person uses marijuana.

Researchers at New York University Langone Medical Center used brain imaging techniques to find the connection, Fox News reports. They say their findings could lead the way to new treatments for PTSD.

“There’s not a single pharmacological treatment out there that has been developed specifically for PTSD,” lead author Dr. Alexander Neumeister said in a news release. “That’s a problem. There’s a consensus among clinicians that existing pharmaceutical treatments such as an antidepressant simply do not work.”

The researchers decided to study CB1 receptors because many PTSD patients use marijuana in an attempt to relieve their symptoms, Dr. Neumeister said. Many say marijuana works better for them than legal medications.

The study included 60 participants who had a PET scan. Some had PTSD, some had a history of trauma but not PTSD, and some had neither. All participants were injected with a radioactive tracer, which traveled to CB1 receptors in the brain, and illuminated them for the scan.

The researchers found people with PTSD had higher levels of CB1 receptors in the parts of the brain associated with fear and anxiety, compared with participants without PTSD. They also had lower levels of a brain chemical that binds to CB1. When a person has lower levels of this chemical, anandamide, the brain compensates by increasing the number of CB1 receptors.

Dr. Neumeister said a new PTSD treatment based on their research should not destroy CB1 receptors, because this could lead to depression. Instead, he is working on a treatment that would restore a normal balance of the endocannibinoids in the brains of people with PTSD. Endocannabinoids are substances that activate cannabinoid receptors. He said this compound does not cause health problems seen in people who are chronic marijuana users. He hopes to start clinical trials of the medication soon.

The findings are published in the journal Molecular Psychiatry.