The latest mental health treatment in Charlotte: Ketamine. A longtime party drug is finding a new role treating depression and PTSD for hundreds of Charlotteans. Why it matters: Ketamine infusion clinics are growing in the city and across the country as research points to the drug's mental health benefits. * More recently, doctors have begun prescribing ketamine off-label, often in the form of IV infusions, nasal sprays and lozenges, to treat severe mental health conditions. By the numbers: The need for new treatments is significant — more than 1billion people worldwide are living with a mental health disorder, according to the World Health Organization. * Then she tried a ketamine infusion at Derive Health in Dilworth, one of several clinics in the Charlotte area offering ketamine as mental health therapy. How it works: Those shifts in perspective are one reason ketamine has emerged as a treatment for conditions like depression and PTSD, says Jonathan Leake, an emergency medicine physician and co-owner of Derive Health and Hydrate Medical.