Researchers, out of the Emory University School of Medicine, publishing a study in Neuropsychopharmacology, have found that increasing or decreasing the body’s endocannabinoid levels has significant impacts on eliminating fear-associated memories. Endocannabinoids are the body’s naturally-produced cannabinoids and have been strongly linked to regulating the body’s fear responses.
In this study, it was demonstrated in mice models that disrupting the endocannabinoid system by blocking cannabinoid receptors increased the retention of memories associated with fear. On the other hand, it was shown that increasing the body’s endocannabinoid levels by preventing their breakdown decreased the retention of fear-associated memories. Additionally, mice with increased endocannabinoid levels were less likely to have fear-responses return when researchers attempted to reinstate them.
These results have profound implications for the treatment and even the prevention of Post-Traumatic Stress Disorder, or PTSD. The disorder is typically treated with anti-depressants, but these drugs treat the symptoms of PTSD rather than its causes. If this study’s results hold true, the body’s endocannabinoid system could be the first line of defense against developing PTSD. CBD is thought to possibly increase the naturally-produced endocannabinoid levels, suggesting it could play a key role in treating and preventing PTSD by reducing the retention of fear-associated memories.
The article’s abstract can be found here
 Ujváry I, Hanus L (2014). "Human metabolites of cannabidiol: a review on their formation, biological activity, and relevance in therapy". Cannabis and Cannabinoid Research. 1 (1): 90–101.