The researchers behind the findings said that THC did not reduce other PTSD symptoms, such as the condition’s severity or depression. For this study, Professor Röpke and colleagues were interested in THC’s established interactions with the human body’s endocannabinoid system. More Than a Third Report Complete Elimination of NightmaresTo start, the team enlisted more than 170 study participants. Finally, the professor said that five out of six study participants in the THC group “felt their health had markedly improved.” For example, they observed that a participant’s PTSD severity and any accompanying depression “did not change conclusively.”