Serious doubts about amyloid-β (Aβ) biomarkers and anti-Aβ immunotherapy.

Reports highlight new Alzheimer's disease treatments using anti-amyloid-β immunotherapy, but we see major concerns. The trials supporting lecanemab and donanemab approvals have methodological flaws, and the benefits may be smaller than the minimal clinically important difference-or absent-since patients with poor tolerance were excluded from efficacy analyses. Moreover, treatment increases amyloid-related imaging abnormalities, suggesting local tissue damage, and is linked to brain volume loss. These issues raise doubts about whether regulators are adequately balancing risks and benefits compared to academic critics.