Alzheimer's Drug Debate: Are Amyloid Antibodies Worth the Risk?

Alzheimer's disease affects tens of millions globally, and until recently no therapy had meaningfully altered its biological course. The emergence of anti-β-amyloid monoclonal antibodies — such as lecanemab and donanemab — represents a genuine scientific milestone, demonstrating for the first time in randomized controlled trials that reducing amyloid burden can slow cognitive and functional decline.

This final paper in a Lancet Series synthesizes the current state of the field, focusing on deep controversies surrounding these therapies. Proponents argue the drugs produce clinically meaningful disease modification; critics contend that modest effect sizes, serious adverse events (notably amyloid-related imaging abnormalities, or ARIA), and high costs do not justify widespread use or regulatory approval.

The authors contextualize the debate by comparing anti-amyloid antibodies to biologics used in oncology, multiple sclerosis, and rheumatoid arthritis — fields where early-generation therapies also faced skepticism before becoming standards of care. They argue that benefit-risk assessments must account for disease severity, lack of alternatives, and the evolving precision medicine landscape.

Looking ahead, the paper outlines a pipeline of next-generation interventions targeting both amyloid and non-amyloid pathways — including tau, neuroinflammation, and synaptic dysfunction — with the goal of achieving greater efficacy and fewer adverse effects. Prevention trials in at-risk populations are highlighted as a critical parallel strategy.

Caveats include the paper's reliance on published trial data without new primary analysis, and the authors' significant industry ties, which may influence framing. Nonetheless, this review provides an authoritative and balanced roadmap for clinicians, researchers, and policymakers navigating one of medicine's most consequential debates.