Marijuana: Good for You or Dangerous? - Consumer Reports

By Jeneen Interlandi

January 13, 2017

The National Academy of Sciences has just completed one of the most comprehensive reviews ever done of marijuana research. In a report released yesterday, doctors and scientists from a wide range of disciplines evaluated more than 10,000 scientific abstracts from which they drew nearly 100 conclusions about the drug’s therapeutic value, its potential for abuse, and its link to diseases ranging from schizophrenia to cancer.

Their findings offer some validation to medical marijuana proponents who have long argued that the drug is effective against a range of maladies, from chronic pain to multiple sclerosis. But owing to a dearth of reliable, high-quality data and several contradictory conclusions, the report as a whole does little to resolve long-standing debates about the risks and benefits of cannabis use. 

Chronic Confusion

When it comes to medicine, few chemicals are as confusing as cannabis. On the one hand, the drug is hugely popular and increasingly legal: Twenty-eight states and the District of Columbia have legalized it for medical purposes; eight of those states plus D.C. have legalized it for recreational use. And according to a recent national survey, 22 million Americans over the age of 12 reported using cannabis in some form or other in the past 30 days

But the plant is is still illegal at the federal level. The Drug Enforcement Agency (DEA) classifies it as a Schedule I substance, meaning that, in their estimation, it has no medical value and a high potential for abuse.

As a result of that classification, reliable scientific research into the plant’s risks and benefits has been paltry, and guidelines for safe and effective use of the drug (as a medication or for fun) remain all but nonexistent, even as its popularity continues to grow.

According to the new report, this failure to provide guidance qualifies as a significant public health threat. “Unlike alcohol and tobacco, which may cause harm, no accepted standards exist for marijuana to help guide individuals as they decide if, when, where, and how to use cannabis,” says Marie McCormick, M.D., a professor of pediatrics at Harvard Medical School and chair of the NAS committee that issued the report.

The report’s authors make several recommendations for repairing this deficit. 

The report’s most significant conclusion is that we urgently need more and better research into the health effects of cannabis consumption.

The Available Evidence

The strongest evidence of benefit was for chronic pain and chemotherapy-induced nausea and vomiting. The committee found conclusive or substantial evidence of a link between the consumption of cannabis and the alleviation of both conditions.

By contrast, they found only limited evidence that cannabis use is linked to an improvement in the symptoms of Tourette’s syndrome, social anxiety, post-traumatic stress disorder (PTSD), or HIV-AIDS-related wasting.

Accidents: The committee found substantial evidence of a link between cannabis use and increased risk of motor vehicle accidents; moderate evidence that the likelihood of overdose injuries in children increases when the drug is legalized; and no or insufficient evidence that marijuana use increases the risk of work-related accidents, overdose deaths, or death from any other cause.

Heart and lung conditions: There was only limited evidence of a connection between cannabis use and heart attacks or strokes.

There was substantial evidence that cannabis use is associated with respiratory symptoms, including a greater frequency of chronic bronchitis episodes. But the evidence of a link between smoking cannabis and developing COPD (cardio-obstructive pulmonary disorder) was limited. And there was no or insufficient evidence of a link between smoking cannabis and developing or exacerbating asthma.

Cancer: There was no evidence that cannabis in any form can treat cancer, including brain and spinal tumors called gliomas. 

Schizophrenia (and other serious mental illnesses): The committee found substantial evidence of a link between cannabis use and the development of schizophrenia, though none of the studies they assessed took genetic factors into consideration or sought to determine which populations might be at greater risk of developing schizophrenia in conjunction with marijuana use.

If you're using cannabis recreationally and are worried about drug dependence or other side effects, you should talk to your doctor about programs to help you quit. 

Last but not least, keep in mind that marijuana and other cannabis products are still illegal in many states.  - Read More

Marijuana: Good for You or Dangerous? - Consumer Reports

DrugFacts: Marijuana | National Institute on Drug Abuse (NIDA)