Cannabis has been used for thousands of years for industrial, recreational, religious, and medicinal purposes. Once valued as a versatile herbal medicine, cannabis has held a volatile place in the medical field since the beginning of the twentieth century. Its decline was deeply influenced by economic, social, and ethical factors. Until recently, it seemed the flowering plant was destined to fall by the wayside: it was classified as a substance of abuse, condemned by governments, and contributed to the problems of drug trafficking. However, in recent years, a growing body of research has begun to demonstrate the medicinal potential of cannabis in the treatment of numerous pathologies. Cannabis’ path from praised healing agent to dismissed substance of abuse has now come full circle.
In the fourth and final installment of our exploration of the history of cannabis, we look at factors such as increased social acceptance, greater levels of legalization, and improved technology that have allowed cannabis to re-emerge as a medicine in the modern era.
A New Era of Medical Research
With the growing legal barriers to research beginning in the 1900s, and the widespread negative opinion of marijuana as a narcotic, it looked like medicinal research of cannabis was destined to end. However, small groups of researchers continued to study the plant and their findings at the end of the twentieth century helped to be propel research forward in new and exciting directions.
This change in the direction of research was driven in part by the discovery of the phytocannabinoids – the components that act on receptors in the human body, found in the cannabis plant.
Cannabidiol was the first phytocannabinoid isolated from cannabis at the end of the nineteenth century. Its structure was elucidated in the early 1930s. It was first synthesized by Dr. Roger Adams and his team at the University of Illinois in 1940 (Pertwee, Br J Pharmacol, 2006; Adams, J. Am. Chem. Soc., 1940). THC, the psychoactive cannabinoid found in cannabis, was isolated and synthesized in 1964 by Israli scientists Yehiel Gaoni and Raphael Mechoulam (Gaoni and Mechoulam, J. Am. Chem. Soc., 1964).
Then, in the 1990s, the discovery of the receptors for cannabinoids and the characterization of the endocannabinoids and the endocannabinoid system, the effective biologic target of phytocannabinoids, renewed scientific interest in cannabis, leading to the publication of thousands of papers over the following decades highlighting the pharmacologic potential of the plant and its components (Russo, Chem Biodivers, 2007; Pertwee, Br J Pharmacol, 2006; Pisanti, Trends Pharmacol Sci, 2017).
As medical research resumed, public perceptions of medicinal marijuana began to change. Patients with conditions that failed to respond to prescription drugs started to turn to cannabis for results (Liu, Lett Drug Disc Des, 2006; Pain, Nature, 2015). Physicians began to take a closer look at research and advocate for change and legalization (Gupta, CNN, 2013; WebMD 2014).
Public pressure forced government bodies to rethink their regulations. Cannabis was decriminalized in the Netherlands in 1976. In 1996, California became the first state to legalize medical cannabis under the Compassionate Use Act. The UK House of Lords started to re-examine the medicinal value of marijuana in 1998 and approved a trial of cannabis in multiple sclerosis in 2000. In 2004, under the UK Misuse of Drugs Act, cannabis was downgraded to a class C drug (Liu, Lett Drug Disc Des, 2006; Pain, Nature, 2015; Pisanti, Trends Pharmacol Sci, 2017).
In 2001, Canada became the first country to adopt a system regulating the medical use of marijuana (CBC News) and several other countries followed suit, endorsing laws that allowed for well-documented therapeutic use and decimalization or even legalization for recreational purposes (Pisanti, Trends Pharmacol Sci, 2017). In the U.S., although federal law still deems possession of cannabis illegal, the medical use of cannabis is legal in 33 states and the territories of Guam and Puerto Rico. The recreational use of cannabis is legal in 10 states and the District of Columbia and it has been decriminalized in three additional states (NCLS – Marijuana Overview; NCLS – State Medical Marijuana Laws).