This prospective study tracked PTSD symptoms and functioning every 3 months over a 12 month period. It was published in the journal Cannabis and Cannabinoid Research in April 2022.
There were 150 total participants with an average age of 50 years old. 73% were men. They were split into a cannabis group and a control group that did not use cannabis.The cannabis group obtained their cannabis legally from a dispensary. The results were very promising:
"Cannabis users reported a greater decrease in PTSD symptom severity over time compared to controls (non cannabis users).
Participants who used cannabis were 2.57 times more likely to no longer meet DSM-5 criteria for PTSD at the end of the study observation period compared to participants who did not use cannabis."
The full text article is behind a paywall, but the abstract is here at LiebertPub.com.