50 million people worldwide have dementia, with 10 million new cases emerging annually. Alzheimer's disease is the most common form of dementia, but for 20-years, there have been no new drugs to tackle the disorder until now. In June, the US Food and Drug Administration approved Aducanumab, a new Alzheimer's medication. While this is a promising development, fierce debate surrounds its efficacy and approval process. FDA Advisory Committee member Dr. Alexander discusses this controversial drug.