Legal access to marijuana, medicinal or otherwise, is growing. In 2016, four states approved recreational use of the drug and four states passed laws related to medical-cannabis access, bringing the total number of states that allow some form of legal marijuana use to 28.

Scientists know that marijuana contains more than 100 compounds, called cannabinoids, that have biological effects on the body. Medically, cannabis can be prescribed for physical ailments like arthritis and cancer symptoms as well as mental health issues like PTSD, depression and anxiety. Still, the role marijuana can play in medicine remains murky. The dearth of research is in large part due to the fact that most studies have focused on illicit use of marijuana rather than its therapeutic potential, and because it’s classified as a schedule 1 drug, making it nearly impossible to study. [Read more at TIME]