A major paper published in The Lancet reports that medicinal cannabis does not effectively treat anxiety, depression, or post-traumatic stress disorder (PTSD). The analysis is the largest to date examining both the safety and effectiveness of cannabinoids across a wide range of mental health conditions. These findings arrive at a time when cannabis use for medical purposes is widespread. About 27 percent of people aged 16-65 in the United States and Canada report using cannabis medically, and ro...