Scientists Across the Globe Call for Greater Awareness of the Harms of Cannabis Use

A new call to action has been released from scientists around the world, reflecting “a growing consensus among experts that frequent cannabis use can increase the risk of psychosis in vulnerable people and lead to a range of other medical and social problems,” according to the The Guardian.

Researchers now believe the evidence for harm is strong enough to issue clear warnings, said the article.  For example, Sir Robin Murray, professor of psychiatric research at King’s College London, stated:

“It’s not sensible to wait for absolute proof that cannabis is a component cause of psychosis. There’s already ample evidence to warrant public education around the risks of heavy use of cannabis, particularly the high-potency varieties. For many reasons, we should have public warnings.”

Estimates suggest that deterring heavy use of cannabis could prevent 8 to 24% of psychosis cases handled by treatment centers, depending on the area. In London alone, where the most common form of cannabis is high-potency marijuana (or “skunk” as it is sometimes called in the United Kingdom), avoiding heavy use could avert many hundreds of cases of psychosis every year.

“It is important to educate the public about this now,” said Nora Volkow, director of the US National Institute on Drug Abuse (NIDA). “Kids who start using drugs in their teen years may never know their full potential. This is also true in relation to the risk for psychosis. The risk is significantly higher for people who begin using marijuana during adolescence. And unfortunately at this point, most people don’t know their genetic risk for psychosis or addiction.”

Ian Hamilton, a mental health lecturer at the University of York, said more detailed monitoring of cannabis use is crucial to ensure that information given out is credible and useful. Most research on cannabis, particularly the major studies that have informed policy, is based on older low-potency cannabis resin, he points out. “In effect, we have a mass population experiment going on where people are exposed to higher potency forms of cannabis, but we don’t fully understand what the short- or long-term risks are,” he said.

Prof Wayne Hall, director of the Centre for Youth Substance Abuse Research at the University of Queensland, said that while most people can use cannabis without putting themselves at risk of psychosis, there is still a need for public education:

“We want public health messages because, for those who develop the illness, it can be devastating. It can transform people’s lives for the worse. People are not going to develop psychosis from having a couple of joints at a party. It’s getting involved in daily use that seems to be the riskiest pattern of behavior: we’re talking about people who smoke every day and throughout the day.”

“When you’re faced with a situation where you cannot determine causality, my personal opinion is why not take the safer route rather than the riskier one, and then figure out ways to minimize harm?” said Amir Englund, a cannabis researcher at King’s College London.

A UK government spokesperson also said its position on cannabis was clear.

“We must prevent drug use in our communities and help people who are dependent to recover, while ensuring our drugs laws are enforced. There is clear scientific and medical evidence that cannabis is a harmful drug which can damage people’s mental and physical health, and harms communities.”

These comments underline the need for a global drug policy that prevents drug use, instead of promoting it. Global drug policy should continue to evolve to match the new scientific evidence available, and that includes taking into account the heavy price that increases in drug use entail, particularly in less-developed countries.

Source:   16th April  2016

Prevent. Don’t Promote. ( is a global campaign that more than 300 organizations across the world are launching at UNGASS 2016 to support the UN drug conventions.  This consortium of organizations advocates fora global drug policy based on public health and safety through the prevention of drug use and drug problems.

Aligned with the principles of Drug Policy Futures, we believe that drug policies should:

  • Prevent initiation of drug use.
  • Respect human rights (for users and non-users alike) as well as the principle of proportionality.
  • Strike a balance of efforts to reduce the use of drugs and the supply of drugs.
  • Protect children from drug use.
  • Ensure access to medical help, treatment and recovery services.
  • Provide access to controlled drugs for legitimate scientific and medical purposes.

Ensure that medical and judicial responses are coordinated with the goal of reducing drug use and drug-related consequences.

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