The Health Ministry has commissioned a comprehensive study into the effects and effectiveness of medical marijuana. The study, which is being carried out by the Israeli National Institute for Health Policy Research, will track up to 2,000 patients using medical cannabis over a two-year period, Haaretz reported on Sunday.

Medical marijuana treatment has become popular and accepted over the last few years in Israel, with about 15,000 registered users and 50 more approved each week by the Health Ministry. Yet there are large gaps in doctors’ understanding of what happens to patients after they begin using cannabis, which the survey will attempt to fill.

There is great enthusiasm for medical marijuana and many find that their condition can be alleviated by its use, but “there are many things we do not know about it,” Pesach Schwartzman, a professor of medicine at Ben-Gurion University who is leading the study, told the paper.

The study, which is already underway, aims to “do proper research on the effects of cannabis” to treat certain conditions and should greatly expand the knowledge base for doctors and patients, Schwartzman said. Information about positive results and negative side effects, the potential for addiction as a result of treatment and why some people stop their medical marijuana treatments are some of the issues to be addressed by the survey.

According to Schwartzman, some of the negative effects of medical marijuana that he says have been underreported, such as the potential for triggering a psychotic episode in those already preconditioned to mental illness, will be examined by the study.

Israel is generally considered to have one of the most forward-thinking and advanced medical marijuana programs in the world, and much of the major scientific research into marijuana is carried out by Israeli institutions. According to the Haaretz report, there are currently only 20 doctors who are authorized to prescribe cannabis, but that number is expected to rise as the demand for medical marijuana increases.

A report from last year indicated proscriptions had risen 30 percent in 2013.