The new Alzheimer’s drug that could break Medicare

Patients are desperate for hope. But there are serious concerns about Biogen’s new $56,000 treatment.

Medicare, the federal health insurance program that covers Americans over 65, is facing an impossible dilemma: Should it cover a new and expensive medication for Alzheimer’s disease, which afflicts 6 million Americans and for which there is no existing treatment, even though the drug might not actually work?

It is an enormous question. Alzheimer’s patients and other families with members who endure mild cognitive impairment that may progress to Alzheimer’s have been waiting decades for an...