PHOENIX (AP) -- Requests to allow medical marijuana use in Arizona for additional medical conditions could be doomed by University of Arizona researchers' reports that they found little or no scientific evidence to support the proposals.
The state Department of Health Services hired university researchers to look for credible scientific articles and studies on harms and benefits of marijuana use for post-traumatic stress, migraine headaches, anxiety and depression.
The requesters included veterans, who have told the department that in some cases, cannabis helps them more than prescription drugs.
Health Services Director Will Humble will decide later this month whether to approve the expansion proposals, and he has said the existence or absence of peer-reviewed scientific studies would play a big role in his decision.
Humble reiterated that stance Friday while saying he has not yet made up his mind on the proposals. He said he has read the university researchers' reports but plans to analyze them further after he receives recommendations due from medical advisers.
"I agree there's not a ton of compelling evidence, but I want to look at it in more depth," he said in an interview.
The Department of Health Services is required under the 2010 law to consider requests to expand coverage. The requests now being considered were the first.
Arizona already permits medical marijuana use for such medical reasons as cancer, glaucoma, AIDS, chronic pain, muscle spasms and hepatitis C.
The state has awarded medical marijuana user cards to more than 28,000 people. Chronic pain is the most common medical condition, though users can have more than one. Most of the users also got permission to grow marijuana until there is a dispensary in their area.
Arizona is among 17 states that allow medical marijuana use, according to the National Conference of State Legislatures.
States' programs vary, and some already cover the additional medical conditions being considered by Arizona. For example, New Mexico allows medical marijuana use for PTSD, while California's covered "serious medical conditions" include migraines. Colorado's decade-old program has denied petitions to add more than a dozen conditions, including PTSD, hepatitis C and depression.
Humble said he feels a need to be cautious about adding conditions because he doesn't want patients to ignore proven treatments in favor of seeking questionable benefits from marijuana.
He also said he needs to be careful because the medical marijuana law doesn't allow him to remove a condition once listed.
"This is a one-way street in these petitions," Humble said. "There's no way to pull it off if later there's data that's harmful."
The four reports prepared by the university researchers said they found relatively few relevant articles and studies. Many were flawed scientifically by being biased or involved clinical trials that were too small.
"There is no credible evidence regarding the effectiveness or harms of marijuana for the treatment of depression," the researchers who prepared that report concluded.
The report on PTSD said the researchers found no research "that directly addressed the key questions of the benefits and harms of marijuana use for treatment of PTSD."
"The most relevant literature generally was of low or very low quality and no conclusions can be drawn about the benefits or harms of marijuana use for the treatment of PTSD," the report said.