The cannabis experiment
As marijuana use becomes more acceptable, researchers are scrambling to answer key questions about the drug.
Daniel Cressey
In 2013, Beau Kilmer took on a pretty audacious head count. Citizens in the state of Washington had just voted to legalize marijuana for recreational use, and the state's liquor control board, which would regulate the nascent industry, was anxious to understand how many people were using the drug — and importantly, how much they were consuming.
The task was never going to be straightforward. Users of an illicit substance, particularly heavy users, often under-report the amounts they take. So Kilmer, co-director of the RAND Drug Policy Research Center in Santa Monica, California, led a team to develop a web-based survey that would ask people how often they had used cannabis in the past month and year. To help them gauge the amounts, the surveys included scaled pictures showing different quantities of weed. The survey, along with other data the team had collected, revealed a rift between perception and reality. Based on prior data, state officials had estimated use at about 85 tonnes per year; Kilmer's research suggested that it was actually double that, about 175 tonnes1. The take-home message, says Kilmer, was “we're going to have to start collecting more data”.
Scientists around the world would echo that statement. Laws designed to legalize cannabis or lessen the penalties associated with it are taking effect around the world. They are sweeping the sale of the drug out of stairwells and shady alleys and into modern shopfronts under full view of the authorities. In 2013, Uruguay became the first nation to legalize marijuana trade. And several countries in Europe — Spain and Italy among them — have moved away from tough penalties for use and possession. Thirty-nine US states plus Washington DC have at least some provisions for medicinal use of the drug. Washington, Colorado, Alaska and Oregon have gone further, legalizing the drug for recreational consumption. A handful of other states including California and Massachusetts are expected to vote on similar recreational-use measures by the end of 2016.
But the rapid shift has caught researchers on the back foot. “Broadly speaking, there's about 100 times as many studies on tobacco or alcohol as there are on illegal substances,” says Christian Hopfer, a psychiatry researcher at the University of Colorado School of Medicine in Denver. “I don't think it's the priority it should be.”
Despite claims that range from its being a treatment for seizures to a cause of schizophrenia, the evidence for marijuana's effects on health and behaviour is limited and at times conflicting. Researchers struggle to answer even the most basic questions about cannabis use, its risks, its benefits and the effect that legalization will have.
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http://www.nature.com/news/the-cannabis-experiment-1.18201
