The FDA approved a new drug that’s been described as a milestone for treating Alzheimer’s disease. Aduhelm is the first treatment for the disease in almost two decades. However, there’s not much evidence that it works. The drug also comes with serious side effects, such as brain swelling. Aduhelm’s drugmaker, Biogen, says it plans to charge about $56,000 a year per patient. Despite the drug’s approval, the FDA is requiring Biogen to conduct another clinical trial. So why put the drug on the market?