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Anti-Amyloid Drugs for Alzheimer's
For the first time, two drugs actually slow Alzheimer's instead of just managing symptoms. Lecanemab and donanemab are antibody infusions that strip amyloid plaque from the brain. In early-stage patients they bend the decline about a quarter slower: roughly five months of preserved function over eighteen months of treatment van Dyck 2023. That is real and FDA-approved. It also costs north of $26,000 a year and carries a real risk of brain swelling. Whether to start is a genuine choice, not an obvious yes.
Decide ยท Course Evidence Moderate Chapter Healthcare

The plaque comes out; most of the disease stays. Alzheimer's brains build up sticky amyloid-beta plaque; these lab-built antibodies flag it for clean-up. It works well: a year of donanemab clears about 84% of plaque, and half of patients go plaque-free and stop 1. But by the time plaque shows on a scan, a second protein called tau is already killing neurons and inflammation is set. So decline slows only about a quarter; it does not reverse.

The numbers. In early-stage trials, lecanemab slowed decline 27% over eighteen months 2; donanemab ran 22% slower overall, 35% slower in low-tau patients, and cut the risk of reaching the next disease stage by 39% 1. Why experts split: that difference is half the size a patient would notice, and pooling the whole drug class finds a smaller average 3. Europe saw the same data and refused donanemab on benefit-versus-risk grounds 4.

Almost nobody qualifies, and this is a neurologist's decision. Bring these questions:

What the win looks like. Over eighteen months, the average treated patient stays themselves about five months longer: the morning routine holds a few more weeks, the grandkids' names take a moment longer to slip, the driver's-licence conversation gets pushed to the next family meeting. Whether the lines keep separating after that is unknown, because the trial's comparison groups are gone 8.

The real cost is money and time. List price is $26,500 a year for lecanemab, about $32,000 for a donanemab course; with scans and workup, year-one cost passes $40,000 9. Medicare covers both if the clinic reports to a registry, but a typical patient still pays around $5,300 in coinsurance. On lecanemab, patient and caregiver visit an infusion centre 26 times a year; that load often decides the call.

The fine print โ€” when to skip it, and what people get wrong

When to skip. Hard stops: more than four old microbleeds or a larger bleed on baseline MRI, surface iron staining, warfarin or a direct blood thinner, or amyloid angiopathy with a prior bleed 6. Unstudied in moderate or severe disease.

What headlines get wrong. It does not reverse or cure Alzheimer's; patients still decline, just slower. It works only for confirmed early Alzheimer's, not other dementias. The brain swelling is not merely a scan number: some patients are hospitalised and a few have died 1.

References
  1. 1Sims JR, et al. (2023). Donanemab in Early Symptomatic Alzheimer Disease: The TRAILBLAZER-ALZ 2 Randomized Clinical Trial. JAMA. link
  2. 2van Dyck CH, et al. (2023). Lecanemab in Early Alzheimer's Disease. New England Journal of Medicine. link
  3. 3Alves F, et al. (2023). Anti-amyloid therapies do not slow Alzheimer's disease progression: a systematic review and meta-analysis. Brain Communications. link
  4. 4EMA (2025). Refusal of the marketing authorisation for Kisunla (donanemab). link
  5. 5Wang Z, et al. (2025). Modified titration of donanemab reduces ARIA risk and maintains amyloid reduction (TRAILBLAZER-ALZ 6). Alzheimer's & Dementia. link
  6. 6Cummings J, et al. (2023). Lecanemab: Appropriate Use Recommendations. Journal of Prevention of Alzheimer's Disease. link
  7. 7Reish NJ, et al. (2023). Multiple Cerebral Hemorrhages in a Patient Receiving Lecanemab and Treated with t-PA for Stroke. New England Journal of Medicine. link
  8. 8Petersen RC, et al. (2023). Expectations and Clinical Meaningfulness of Randomized Controlled Trials. Alzheimer's & Dementia. link
  9. 9CMS (2023). Statement: Broader Medicare Coverage of Leqembi Available Following FDA Traditional Approval. link
Related in the handbook (5)
Related
  • โ€” Before reaching for an expensive, risky drug, clear out the everyday meds quietly fogging the same brain.
  • โ€” Your APOE status shapes both eligibility and the brain-bleed risk of these drugs โ€” test before deciding.
  • โ€” Slows decline sounds big until you read the actual size โ€” about five months over eighteen.
  • โ€” The shingles shot appears to cut dementia risk about a fifth โ€” the same disease these drugs treat once it has already taken hold.
  • โ€” A specific stage of Alzheimer's is one of the narrow places high-dose vitamin E has supervised evidence.
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