A team of Australian scientists found ‘insufficient evidence to provide guidance on the use of cannabinoids for treating mental disorders.’

In recent years, scientists have asked the federal government to remove cannabis as a Controlled Substance so that they can more effectively study its effects. Studying marijuana is notoriously difficult and scientists often receive less than ideal cannabis flower from the government to conduct research. In some cases, the weed is moldy and flowers are ground with stems and seeds, which makes it difficult to conduct precise research.

As marijuana explodes into the mainstream and becomes a preferred medicine to treat certain conditions, we need more research before making definitive claims. A recent study around the efficacy of treating anxiety and depression symptoms with marijuana would agree with that sentiment. In what is being called the most comprehensive review around marijuana and mental health, researchers say the evidence isn’t there.

RELATED: Do Cannabis Products Over Promise And Under Deliver?

“There remains insufficient evidence to provide guidance on the use of cannabinoids for treating mental disorders within a regulatory framework,” the study’s authors wrote.

Published in the Lancet Review, a team of Australian scientists collated data from 83 previous studies on medical marijuana’s effects on mental health. They wanted to know how medical cannabinoids affected conditions such as ADHD, PTSD, depression, anxiety, Tourette syndrome, and psychosis. They did find positive results in some cases, such as studies where pharmaceutical CBD-THC reduced symptoms of anxiety and PTSD, and one where patients with psychosis saw some benefits. Overall the literature failed to meet the standard criteria necessary for a drug to be considered safe and effective for widespread use.

“Clinicians and consumers need to be aware of the low quality and quantity of evidence for the effectiveness of medicinal cannabinoids in treating mental health disorders and the potential risk of adverse events,” the authors wrote.

Research where marijuana improved mental health conditions often correlated with using cannabis to treat other diagnoses. For example, patients who were prescribed marijuana to treat multiple sclerosis or chronic pain saw a reduction in those symptoms, which then improved their mental health conditions.

RELATED: How Cannabis And CBD Can Help Eliminate The Stigma Around Mental Illness

The other complication around medical literature regarding marijuana is that scientists often utilize observational models as a loophole to conduct research. In these cases, they can’t control the quality of cannabis being used by participants. Of the 83 studies the Australian scientists reviewed, only 40 were randomized controlled trials, which is the “gold standard” in drug research testing. In randomized controlled trials, participants don’t know whether they’re receiving the drug or not. Researchers behind the study suggested a placebo effect could be occurring in some anecdotal reports of marijuana improving mental health conditions.

“In light of the results of this comprehensive review and meta-analysis, it would be hard for practitioners to justify recommending the use of cannabinoids for psychiatric conditions at this time,” Dr. Deepak Cyril D’Souza, who serves as a professor of psychiatry at Yale University, noted in a commentary that accompanied the new study.