The amyloid hypothesis has driven Alzheimer's research for 30 years, and the first FDA-approved disease-modifying drugs — lecanemab and donanemab — do clear amyloid plaques. But a major Cochrane meta-analysis found they produce little-to-no meaningful cognitive benefit, igniting fierce debate among leading researchers. The drugs slow decline statistically, but whether patients can actually feel the difference remains deeply contested.
The Alzheimer's field is deeply divided. A Cochrane meta-analysis of 17 randomized controlled trials (20,000+ patients) concluded that antiamyloid drugs like lecanemab and donanemab clear amyloid plaques but offer little-to-no meaningful cognitive benefit. Researchers who helped build the field called the review analytically flawed; others called it "the truth we don't want to hear." The drugs are FDA-approved and hit their trial endpoints — but whether they help patients in any perceptible way remains genuinely unresolved.
The crux of the dispute is a number: lecanemab slowed cognitive decline by just 0.45 points on an 18-point scale over 18 months; donanemab managed 0.67 points. Both fall below the estimated threshold of what a patient or clinician can actually perceive. Defenders argue the benefit compounds over years; critics say patients "have to trust us because they cannot tell." Safety concerns — including brain swelling, microhemorrhages, and dangerous interactions with blood thinners — narrow the eligible population further.
Key Takeaways:
Why it matters: With a $26,500/year list price, significant safety monitoring requirements, and benefits patients may not feel, the field faces a reckoning — scientific, ethical, and economic. The next frontier is likely combination therapy targeting both amyloid and tau, but for now, prescribing these drugs remains, in one expert's words, "a little bit of an act of faith."
