The Canadian Forces and Veterans Affairs are setting up a clinical trial to evaluate the safety and efficacy of using medical marijuana to treat post-traumatic stress disorder in military members and veterans.

A briefing note to the veterans affairs minister from October reveals a senior psychiatrist with the Canadian Forces "has drafted a preliminary protocol to conduct a clinical trial" that would look at how effective and safe marijuana is in treating PTSD. But as of October the biggest obstacle was finding a way to fund the study and research team needed to implement it.

"VAC and CAF are working to further develop the protocol, partnership and funding," said the briefing note obtained by CBC News under the Access to Information Act.

"The biggest challenge will be finding a mechanism to transfer funds in an expeditious manner to a research team to implement the study," it said.

According to a spokesperson for the Canadian Forces Health Services, the military and Veterans Affairs are in the "very early stages of developing a research project … to study the safety and efficacy of marijuana in the treatment of mental health disorders."

Veterans Affairs reimburses veterans for up to three grams of medical marijuana a day, for a variety of reasons, including to relieve symptoms of PTSD. That amount was lowered from 10 grams a day last fall after an auditor general's report questioned how the department arrived at that number, citing a lack of evidence.

That same auditor general's report revealed the number of veterans receiving medical marijuana had jumped from 112 in fiscal year 2013-14 to 1,320 in in the nine months between April and December 2015.

A spokesperson for Veterans Affairs said in an email to CBC that since the department changed the reimbursement policy for medical cannabis it has "been reviewing existing research" and wants to ensure that the study with the military "will have the greatest impact on strengthening evidence on the effects of marijuana on the health of veterans."

Neither Veterans Affairs nor the military would provide more details about the study, when it will begin, or how much it will cost.

More research needed

Although Veterans Affairs reimburses veterans for medical cannabis, and a number of veterans with PTSD say it does help, there is little empirical data showing the effects of cannabis on people with PTSD, which is why experts say clinical trials are needed.

Zach Walsh is an associate professor at the University of British Columbia and the principal investigator on a Canadian clinical trial for using medical cannabis to treat PTSD, currently underway at UBC.

Walsh said trials like this are needed, but that anecdotal evidence from veterans already using cannabis to get relief from PTSD symptoms should also be taken into account.

"I don't want that to eclipse, in the meantime, the importance of what we're hearing from veterans, some of whom report very good effects. We want to pay attention to the patients," he said.

The UBC trial is being run in partnership with Tilray, a medical cannabis producer. It includes 42 people and is a randomized clinical trial, which is known as the gold standard when it comes to testing the efficacy of a drug.

Results from the UBC trial will be available in about a year and a half to two years. But Walsh said one study will not be conclusive and more clinical trials will be needed before any conclusions on the efficacy and safety of using medical cannabis to treat PTSD can be made.