The FDA has approved Biogen's Alzheimer's drug, aducanumab, which will be marketed as Aduhelm. Biogen is charging $56,000 per year for the drug.

Why it matters: Aduhelm is the first federally approved Alzheimer's treatment in roughly 18 years, but there is no conclusive evidence the drug slows the decline of memory and brain function.

Drilling down: The FDA issued an "accelerated approval" for Aduhelm, an IV drug that must be administered in a doctor's office and comes with official warnings of possible brain swelling and bleeding.

• "Accelerated approval" requires Biogen to conduct a post-approval confirmatory trial to test whether the drug actually shows any cognitive benefit.
• "If the confirmatory trial does not verify the drug’s anticipated clinical benefit," according to the FDA, the agency and drug company could pull the drug from the market.

Yes, but: Biogen will still be able to sell Aduhelm while the confirmatory trial is ongoing.

• And as we have seen with other drugs that have been granted "accelerated approval," failed drugs don't get removed easily. Enrolling patients in confirmatory trials is also difficult because patients may want to try the treatment now instead of participating in a study.
• "I continue to think that there is a very high chance that all of that will be wasted money," drug chemist and blogger Derek Lowe tweeted.

The bottom line: Billy Dunn, the FDA neuroscience director who ultimately signed off on Aduhelm, wrote in a memo that the agency "used a rigorous, science-based approach to assess this therapy." Almost the entire scientific and medical community disagrees and worries this decision tarnishes the FDA's credibility.