A new study says marijuana is a powerful aid in reducing chronic pain and helping fight nausea, but conclusions on many other benefits and risks aren’t so clear. The report released yesterday analyzed ten-thousand scientific studies on the drug. The report says there is little or no evidence that weed helps or hurts in treating diseases and conditions including cancer, epilepsy, schizophrenia, Parkinson’s disease, and addiction. On the downside, it finds that using marijuana might raise the risk of developing mental health issues including anxiety, schizophrenia, and to a lesser extent, depression. The National Academies of Science, Engineering, and Medicine prepared the report.