Biggest Study Yet: Medical Weed Unproven

The first comprehensive analysis of research on the benefits of medical marijuana has shown the drug is not proven to work for many illnesses, despite states approving it to treat those illnesses. There is strong evidence that marijuana can alleviate chronic pain and muscle stiffness in multiple sclerosis, but there is weak evidence for positive effects on anxiety, sleep disorders, and Tourette syndrome. The analysis, published Tuesday in the Journal of the American Medical Association, looked at 79 studies that involved more than 6,000 patients.