A new study from Australia did not find strong evidence that cannabis helps psychiatric disorders, and the authors conclude that the low quality and quantity of evidence does not support its use. The study appeared in the prestigious journal The Lancet Psychiatry.

But medical marijuana advocates say the problem is the lack of research rather than the results of studies that have been conducted, according to an article in US News & World Report.

The researchers included 83 studies—42 for depression, 31 for anxiety, 12 for post-traumatic stress disorder (PTSD), 11 for psychosis, eight for Tourette’s syndrome and three for attention-deficit hyperactivity disorder (ADHD). The studies largely used pharmaceutical THC, which may or may not have contained CBD, a component of cannabis that has been associated with reduced anxiety.

While the study showed few positive findings, THC increased the number of people who had adverse events in 10 studies, leading the authors to warn patients about the risks of using cannabis.

“These results are consistent that THC exacerbates psychosis. It doesn’t alleviate it,” study authors said. In some people, they note, certain sativa-dominant strains of cannabis may worsen anxiety. The authors also state that THC can harm sleep and cause mood problems.

Medical marijuana advocate Mitch Earleywine, a professor of psychology at State University of New York, Albany, told USNews: “Unfortunately, I would guess that headlines worldwide will claim directly or indirectly that cannabinoids are no help, but in fact, we don’t know if they do or not.”