Aduhelm, known generically as aducanumab, is the first drug to actually affect the underlying disease process associated with Alzheimer's. Yet sales have been limited, and the drug is reaching very few patients — at least so far. It's expensive, risky and likely doing little to improve patients' lives. NPR science correspondent Jon Hamilton explains why doctors and patients aren't excited about the new drug and what it could mean for future Alzheimer's drugs.Additional links:- Jon's reporting on aducanumab: https://n.pr/3bDV0MY- Jon's reporting on future Alzheimer's treatments: https://n.pr/3bDUsqoYou can always reach the show by emailing shortwave@npr.org.