Dr. Burghardt’s study showed that when rats were treated with an SSRI called tianeptine, it drastically altered their capacities for fear extinction. Rats that received short-term SSRI treatments—they got the drug for 9 days—developed a greater capacity for fear extinction. Conversely, rats that were treated for 22 days saw their ability to cultivate fear extinction become impaired.
Researchers also noted that in the group treated for 22 days, there was a decrease in the amount of a particular receptor protein largely affected by serotonin activity. This suggests that the protein, called the NR2B subunit of the NMDA glutamate receptor, is crucial in mediating the fear responses. Which means that the many people taking antidepressants for PTSD may be quashing their ability to successfully instigate fear extinction.
His study, published in Molecular Psychiatry, found differences in the amounts of the neurotransmitter anandamide and its corresponding CB1 receptor in the brains of humans with post-traumatic stress disorder, as compared with their normal counterparts. PTSD patients had decreased levels of anandamide, which has long been implicated in mechanisms involved with learning
In fact, Dr. Neumeister said that “people with PTSD who use marijuana—a potent cannabinoid—often experience more relief from their symptoms than they do from antidepressants and other psychiatric medications.”