Biogen, FDA narrow label of new Alzheimer's drug

Biogen has updated the prescription information for the experimental Alzheimer's treatment Aduhelm, saying the drug "should be initiated in patients with mild cognitive impairment or mild dementia stage of disease" instead of people who have more advanced Alzheimer's.

Why it matters: It's an unusual step to modify a drug's label so soon after approval, raising questions about why the FDA approved the drug for such a broad patient population in the first place.