The studies available today point to several reasons. One is that cannabis reduces amygdala activity; since the amygdala is the part of the brain that is associated with our fear-based response to perceived threats. A study conducted by Wayne State University researchers revealed that PTSD sufferers who consumed THC displayed a decrease in amygdala activity, which means that they had less measured symptoms of fear and anxiety in situations that would normally elicit trauma-based responses from them.