The F.D.A. worked closely with the company to study the data. But after careful review, an outside advisory committee for the agency was nearly unanimous in its ruling that the drug had failed to show strong evidence that it worked. Committee members were also concerned about the drug’s safety, since about a third of patients taking a higher dose had evidence of brain swelling. One of us, Dr. Kesselheim, was a member of that committee and has resigned as a result of the F.D.A.’s inexcusable decision to approve the drug anyway. In approving aducanumab, the F.D.A. shifted the goal posts. It unexpectedly approved the drug based on a theory that it could affect amyloid protein levels in the brain. Amyloid buildup in the brain is considered a marker for Alzheimer’s disease, but lowering amyloid levels with a drug has never been shown to slow cognitive decline. Dozens of investigational drugs have lowered amyloid levels without affecting the progression of this terrible disease. Even worse, although aducanumab was tested only in patients with mild disease, the F.D.A. inexplicably approved it for use in any person with Alzheimer’s, regardless of severity. It enters the market now as a monthly intravenous infusion with a $56,000 price tag and the need for regular M.R.I. scans to monitor for the possible brain swelling it can cause.