Landmark study: marijuana is effective medicine, but has drawbacks

Marijuana and its derivatives can be effective medicines for treating pain, nausea, vomiting, muscle spasms and other conditions, but cannabis is not harmless, and more research is needed, the nation’s top scientists concluded in a landmark review of research released Thursday. The nonprofit National Academies of Sciences, Engineering and Medicine issued their report, “The Health Effects of Cannabis and Cannabinoids,” summarizing the current state of evidence for the efficacy of medical marijuana and recommending new studies. Even though marijuana has no lethal overdose level, the federal government ranks marijuana as “Schedule 1” — above prescription opioids like Vicodin and OxyContin that were linked to more than 180,000 deaths from 1999 to 2015. “Conclusive or substantial evidence” confirms cannabis can treat chronic pain, nausea, vomiting, and multiple sclerosis spasticity. There is moderate evidence cannabis can improve sleep, and limited evidence pot or its derivatives can help manage post-traumatic stress disorder and anxiety. “The growing acceptance, accessibility, and use of cannabis raise important public health concerns and there is a clear need to establish what is known and what needs to be known about the health effects of cannabis use,” the report stated. Shifting public sentiment, conflicting and impeded scientific research, and legislative battles have fueled the debate about what, if any, harms or benefits can be attributed to the use of cannabis or its derivatives, the study said. Unlike with legal tobacco or alcohol, studies show cannabis does not cause lung, head or neck cancer, the report found. [...] the report also diminishes some claims of medical marijuana advocates, finding, for instance, that there is not sufficient evidence cannabis or its compounds can treat cancer, epilepsy, or schizophrenia. Cannabis can also be hard on the circulatory system and there is “limited evidence” of a link between pot smoking and heart attack, or stroke. Maternal cannabis smoking could be linked to lower birth weight, the review finds, but there is little evidence it causes pregnancy complications or later negative outcomes in offspring. The scientists found some evidence of a link between pot use and certain mental health conditions like depression, but also moderate evidence that there’s no link between cannabis use and the worsening of negative symptoms of schizophrenia. The study highlights the need to change federal law with regard to cannabis’ Schedule 1 designation and its illegality, said Amanda Reiman, the marijuana law and policy manager for the pro-legalization Drug Policy Alliance. Arizona physician Dr. Sue Sisley, who has tried for years to get federal approval to study cannabis’ impact on post-traumatic stress disorder, said “it’s unsurprising” the National Academies failed to find evidence cannabis can treat cancer or epilepsy. The review refutes critics’ claim that there’s not enough research to support pot decriminalization or legalization, said Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws.