Centuries of anecdotal evidence have held that cannabis has significant therapeutic value. Advances in scientific technology can now tell us exactly why cannabis does what it does to the human body, allowing us to fine-tune the desired effects and apply them to a staggering range of ailments. Here is a look at six countries whose scientists, with varying degrees of government support, are making huge strides in medical cannabis research.

The Netherlands

Although The Netherlands, and Amsterdam in particular, occupy a place in the popular imagination as a haven of recreational use, cannabis is technically illegal in the country, and Amsterdam’s notorious coffeeshops operate under a loose system of legal toleration. The Netherlands’ scientific approach to cannabis, however, is much more rigorous. Operating out of the University of Utrecht, Structural Formulas of Main natural cannabinoidsthe Association for Legal Cannabis and its Constituents for Medicinal Use aims to study the medical effects of not only cannabis but its various synthetic approximations and processed derivatives like hash. The organization conducted a thorough comparative study of the effectiveness of cannabis flowers and pharmaceutical cannabinoid preparations like Nabilone and Dronabinol in different health problems; ultimately, the study concluded that THC — whether organic or synthetic — was notably effective in relieving symptoms related to loss of appetite, chronic pain, and multiple sclerosis.

Czech Republic

Czechs ranks among the most avid cannabis users in Europe. A 2014 E.U. report estimates that about 28% of adults in the Czech Republic have used cannabis at least once — for some perspective, that’s two percentage points higher than The Netherlands, and right on par with Spain, where private cannabis clubs have been thriving since 2001. Although sale, possession, and cultivation for recreational purposes are all illegal, laws are decriminalized and rarely enforced. Medical cannabis has been legal since 2013, a move that has opened up opportunities for large-scale research.

Founded in 2015, the International Cannabis and Cannabinoids Institute counts a comprehensive analysis of individual strains and the development on new cannabis industry patents among its efforts.

Tomáš Zábranský, who serves as the institute’s Chief Scientist, has been studying the potential medical benefits of cannabis and advocating for a measured, scientific approach to tolerance for decades.

Canada

The head shops and dispensaries that dot Granville Street in downtown Vancouver are a testament to Canadians’ embrace of medical cannabis, which has been legal in the country since 2001. The informal and fairly lax nature of the retail market, though, belies Canada’s position as a leader in scientific cannabis research. glass tube with marijuana Vancouver’s own University of British Columbia in particular has studied various aspects of cannabis use like the role of mood on pain relief and patterns of use among students through its Centre for the Advancement of Psychological Science and Law.

Most recently, the organization has received approval from Canada’s national health board to study the efficacy of cannabis in relieving symptoms of PTSD.

The first major study of its kind, which aims to standardize a new treatment for the condition, which affects millions worldwide.

United States

Before prohibiting it in 1937, the U.S. championed an approach to studying cannabis that was marked more by pseudoscience and sensationalism than by actual research. Federal Bureau of Narcotics commissioner Harry J. Anslinger even went to great lengths to discredit and bury a statistically-sound report by NYC mayor Fiorello LaGuardia which concluded that cannabis did not lead to addiction or rampant crime. Although Dr. Lester Grinspoon brought some mainstream academic attention to cannabis research in the 1960s and 70s, it took years of petitioning and reform for cannabis to achieve more widespread institutional acceptance.

One group in particular, the University of California’s Center for Medical Cannabis Research, has studied the medical and social science facets of cannabis use, like the effectiveness of vaporization and the implications of cannabis intoxication on driving. Unfortunately, more intensive study in the U.S. is hampered by some circular legal logic: in August 2016, the Drug Enforcement Administration reaffirmed its classification of cannabis as a Schedule I drug with “no currently accepted medical use” — a ruling that both ignores current evidence and precludes any further research with some hefty red tape.

United Kingdom

Cannabis is very popular in the U.K. — approximately 30% of adults have used it at least once in their lifetime. On a 1998 visit to a nursing facility, no less of a symbolic figure than Prince Charles even suggested that a multiple sclerosis patient use cannabis to treat her symptoms. Although it remains criminalized throughout the U.K., the Home Office allows for a certain number of plants to be cultivated for clinical trials.

Studies at the University of Nottingham suggested that cannabis, in conjunction with synthetically-produced cannabinoids and the body’s naturally-occurring endocannabinoids, can ease symptoms of arthritis and reduce the severity of stroke damage.

Dr. David Nutt, meanwhile, has pioneered research on some of the more psychological and sociological effects of cannabis use — he was dismissed from a government drug advisory council after suggesting that recreational cannabis use carries a very small risk of harm relative to alcohol and other drugs, and that the U.K.’s prohibitive cannabis policies might actually work to perpetuate irresponsible cannabis use.

Israel

Israel is the indisputable global frontrunner in cannabis research. Since Dr. Ralph Mechoulam identified THC as the key psychoactive compound in cannabis while working at Israel’s Weizmann Institute in 1964, the country has actively encouraged and funded research on the drug’s medical benefits. THC compoundAfter discovering THC, Mechoulam and his colleagues were the first to isolate endocannabinoids in the human body, paving the way for the creation of synthetic cannabinoids in laboratories.

Subsequent research has focused on the role that CBD — the more physically-active compound in cannabis — plays in brain chemistry.

With government support, the company Tikun Olam (whose name comes from a Judaic concept meaning roughly “repair of the world”) works with scientists to develop high-CBD and low-THC strains that are fine-tuned for the relief of specific symptoms and conditions. Israel’s progressive attitude towards research has even triggered some “brain drain” out of the U.S. — among others, Harvard-trained Dr. Alan Shackleford has begun conducting research in Israel to take advantage of the country’s “world-class” resources.

Vincent Ballantine

About the author: Vincent Ballantine is a Brooklyn-based writer. A native New Yorker, he holds a degree in English from Georgetown University and has written on television, pop culture, travel, and health.