Which prescription drugs for Alzheimer’s have FDA approval and what benefits and risks do they carry?

1. Which drugs have FDA approval and how they’re grouped

The FDA has converted and granted traditional approvals to two anti‑amyloid monoclonal antibodies for early Alzheimer’s disease: lecanemab (Leqembi) and donanemab (Kisunla), both approved for people with mild cognitive impairment or mild dementia who have confirmed elevated brain amyloid ^{[4] [1] [7]}. Earlier controversies remain around aducanumab (Aduhelm)—approved via accelerated pathway in 2021 but mired in debate and largely withdrawn from the market—which is distinct from these newer approvals ^{[6] [8]}. Symptom‑focused medicines—longstanding cholinesterase inhibitors and memantine—remain in use, and newer symptomatic agents cited in reporting include Zunveyl (benzgalantamine) for mild‑to‑moderate Alzheimer’s and brexpiprazole (Rexulti) for agitation ^{[1] [2] [3]}.

2. What benefits the disease‑modifying antibodies deliver

Lecanemab and donanemab have demonstrated the first reproducible slowing of clinical decline by removing amyloid plaques, with statistically significant but modest effects on cognitive and functional scales in early disease trials ^{[4] [7] [9]}. Donanemab showed a 35% slowing in a subgroup with low/medium tau and about 22% slowing in a broader trial population compared with placebo in phase 3 analyses, while lecanemab’s confirmatory trial met endpoints showing less decline over 18 months ^{[5] [10] [4]}. Professional guidance emphasizes earlier treatment provides greater benefit and that disease‑modifying therapies are likely to be paired with symptomatic care and lifestyle strategies ^{[11] [9]}.

3. The safety risks that shape clinical decisions

All anti‑amyloid antibodies carry the risk of amyloid‑related imaging abnormalities (ARIA), including brain swelling (ARIA‑E) and micro‑hemorrhages (ARIA‑H), risks that are more common in carriers of the APOE4 gene and may be significant enough to require MRI monitoring and treatment pauses or discontinuation ^{[9] [11] [5]}. Lecanemab’s labeling cautions about intracerebral hemorrhage risk, interactions with anticoagulants and rare hypersensitivity reactions ^[4]. Trial safety signals and mortality differences raised alarms during earlier approvals and contributed to clinician and patient hesitancy around some agents ^{[6] [8]}.

4. Practical burdens: testing, monitoring, cost and access

Prescription of these antibodies requires confirmation of brain amyloid—traditionally by PET but increasingly by blood tests—and serial MRI monitoring, creating logistical hurdles that limit access to a subset of patients seen at equipped centers ^{[9] [12]}. Medicare now covers Leqembi and Kisunla, but the rollout has been slowed by infrastructure gaps, monitoring burdens and lingering questions about long‑term outcomes and cost‑effectiveness ^{[9] [12]}. Clinicians and health systems must weigh not only clinical benefit but also monitoring capacity, insurance pathways and patient selection criteria ^[11].

5. Debate, uncertainty and the road ahead

The approvals represent a watershed—proof that targeting amyloid can alter disease trajectory—but the magnitude, durability and real‑world meaningfulness of benefit remain contested, and the FDA’s earlier accelerated approvals (e.g., aducanumab) exposed tensions between regulatory urgency and evidentiary standards ^{[6] [8] [4]}. Experts call for shared decision‑making that clearly explains modest expected benefit, safety risks, monitoring burdens and unknowns about long‑term quality‑of‑life improvement, while research continues on other mechanisms (tau, inflammation, vascular health) and combination strategies ^{[11] [9]}.