In March 2019 biotechnology giant Biogen stopped two big trials of its experimental Alzheimer's disease drug aducanumab because it did not appear to improve memory in declining patients. Then, in a surprise reversal several months later, the company and its partner, Japanese drugmaker Eisai, said they would ask the U.S. Food and Drug Administration to approve the treatment. A new analysis, Biogen said, showed that a subset of people on the highest doses in one trial did benefit from the compound, which dissolves clumps of a protein called beta-amyloid within the brain.