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Who Qualifies for Lecanemab or Donanemab? A Practical Guide for Early-Stage Alzheimer’s Families

If you or your loved one is in the very earliest stages of Alzheimer’s disease, you may have heard about two new medications—lecanemab and donanemab—that can modestly slow cognitive decline. But not everyone can take them. This article walks you through the specific eligibility criteria, what tests are needed, and who is typically excluded. You’ll find clear steps to discuss with your doctor, real-world safety insights, and practical tools to help you navigate this complex decision with confidence and hope.

Key points

  • Lecanemab and donanemab are for early-stage Alzheimer’s only—mild cognitive impairment or mild dementia with confirmed amyloid in the brain.
  • You must have an amyloid PET scan or lumbar puncture to prove amyloid is present; otherwise, these drugs won’t work.
  • People with bleeding disorders, on blood thinners, or with active autoimmune conditions are typically excluded due to ARIA risk.
  • APOE e4 genetic testing is recommended before starting; carriers have higher risk of brain swelling.
  • These drugs slow decline modestly (about 27% over 18 months) but are not a cure—set realistic expectations.
  • Preliminary data from AAIC 2025 suggests safety comparable to clinical trials, but these findings are early and need confirmation. Individual monitoring is essential.

What Are Lecanemab and Donanemab?

Lecanemab and donanemab are anti-amyloid antibody therapies—a new class of Alzheimer’s drugs approved by the FDA. They work by targeting and removing amyloid protein that builds up in the brain during Alzheimer’s disease. Unlike older medications that only manage symptoms (like donepezil or memantine), these drugs actually modify the disease process itself, slowing progression modestly. But they are not a cure, and they are not for everyone. They are specifically designed for people in the earliest stages of Alzheimer’s, when cognitive changes are still mild and a doctor can objectively verify them.

Why Eligibility Is So Strict

The reason these drugs have narrow eligibility criteria is safety. Both medications carry a risk of a side effect called ARIA (amyloid-related imaging abnormalities), which can cause brain swelling or small hemorrhages. To minimize that risk, researchers designed clinical trials to exclude people with conditions that increase bleeding tendency, such as taking blood thinners or having a history of stroke. Additionally, because these are immunologic medications, people with active autoimmune conditions or those on other immunotherapy drugs are typically excluded. The goal is to ensure that the person receiving the drug has Alzheimer’s pathology—not another cause of cognitive decline—and that their brain is as healthy as possible before starting treatment.

The Two-Step Qualification Process

To qualify, you must first have early cognitive symptoms that a doctor can objectively verify—this usually means a clinical diagnosis of mild cognitive impairment (MCI) or mild Alzheimer’s dementia. The second step is to confirm that amyloid plaques are actually present in your brain. This is done either through a PET scan that images amyloid or through a lumbar puncture (spinal tap) to measure amyloid levels in cerebrospinal fluid. Without this confirmation, the drugs cannot be prescribed, because they only work if amyloid is the underlying problem. If your cognitive issues are caused by another condition—like vascular dementia, Lewy body dementia, or a psychiatric disorder—these medications will not help and may even cause harm.

General caregiving information, not medical advice. Check medications and major care changes with your clinician.

Step-by-step

  1. Schedule a comprehensive evaluation with a neurologist or geriatrician who specializes in memory disorders. Ask for a full cognitive assessment (such as the MoCA or MMSE) to confirm that symptoms are in the mildest stage—mild cognitive impairment or mild Alzheimer's dementia.

  2. Confirm amyloid presence in the brain with either a PET amyloid scan or a lumbar puncture; both are covered by Medicare for this purpose in the US.

  3. Review your full medical history with your doctor for conditions that may exclude you—including other neurological or psychiatric causes of cognitive impairment, active autoimmune disease, bleeding disorders, or current use of blood thinners (which raise ARIA risk).

  4. Ask about APOE e4 genetic testing. The FDA recommends it before starting either drug because people with two copies of the gene have a substantially higher risk of serious ARIA side effects.

  5. If you qualify, you'll start on a low dose that is gradually increased over several weeks. Lecanemab is given as an IV infusion every two weeks and donanemab every four weeks.

  6. Plan for regular brain MRI monitoring—a baseline scan before treatment, then follow-ups before your second, third, and fourth infusions, and every six months thereafter. These scans are essential for catching ARIA (brain swelling or small bleeds) early.

  7. Keep a simple symptom diary and report any new or worsening headaches, vision changes, confusion, nausea, or falls to your doctor right away. If you see no improvement or continued decline after three to six months on the full dose, have an honest conversation about whether to continue.

  8. Set realistic expectations: these drugs slow progression by roughly 27% over 18 months compared with placebo, meaning you may gain a few extra months of better function, but the disease still progresses.

What not to do

  • Do not assume you qualify just because you have memory loss. Many conditions mimic Alzheimer's—vitamin B12 deficiency, thyroid problems, depression, sleep apnea—and a full diagnostic workup is required first.

  • Do not stop taking blood thinners on your own. If you are on an anticoagulant, your doctor must weigh the bleeding risk against the potential benefit; stopping suddenly can cause a stroke or blood clot.

  • Do not expect immediate improvement. These drugs slow decline rather than reverse symptoms.

  • Do not ignore side effects such as headache, vision changes, or confusion—these can be signs of ARIA, and reporting them promptly lowers the risk of permanent injury.

  • Do not take lecanemab and donanemab together. They have not been studied in combination, and you should be on only one, as prescribed.

  • Do not assume Medicare or insurance will cover every cost. While Medicare Part B typically covers the infusions and required MRIs, copays and deductibles may apply—check with your insurer and the drug manufacturer's patient assistance programs.

Practical tools

  • Doctor Discussion Guide: Questions to Ask About Eligibility

    Print this list and bring it to your appointment: (1) 'Do I have mild cognitive impairment or mild Alzheimer's dementia?' (2) 'Do I need an amyloid PET scan or lumbar puncture to confirm amyloid?' (3) 'Should I get tested for the APOE e4 gene?' (4) 'Are there any conditions in my history that would exclude me?' (5) 'What is my personal risk of ARIA?' (6) 'How often will I need MRIs?' (7) 'What will this cost, and what does my insurance cover?'

  • Symptom and Side Effect Log

    Use a notebook or a free app like CareClinic to track daily: memory (1–10), confusion (1–10), headache (yes/no), vision changes (yes/no), nausea (yes/no), and any falls or dizziness. Bring the log to every infusion and MRI appointment so your doctor can spot ARIA early.

  • Infusion Day Checklist

    Before each infusion: (1) confirm appointment time and location, (2) bring a list of all current medications including over-the-counter and supplements, (3) bring a snack and water, (4) bring something to do for the hour-plus of infusion and observation, (5) arrange a driver in case you feel drowsy afterward, and (6) note any new symptoms since your last visit.

  • Phrases to Say When Discussing ARIA Risk

    If you are worried about side effects, try: 'I understand ARIA is possible—can you explain what symptoms I should watch for at home, and if I have a headache or vision change, should I go to the ER or call your office first?' Also ask: 'If I develop ARIA, what is the treatment, and will we stop the drug temporarily or permanently?'

  • Qualification and Monitoring Schedule Tracker

    Map out every appointment in one place: specialist consult, cognitive testing, amyloid PET or lumbar puncture, APOE blood test, baseline MRI, infusion schedule (every 2 weeks for lecanemab or every 4 weeks for donanemab), and follow-up MRIs (before the 2nd, 3rd, and 4th infusions, then every 6 months). A simple calendar or spreadsheet helps you and your care partner stay ahead of the testing cadence.

Discuss with your clinician

Ask your doctor: 'Based on my cognitive test scores and amyloid scan, am I a good candidate for lecanemab or donanemab?'

Ask: 'Should I get genetic testing for APOE e4 before starting? If I am a carrier, what is my personal risk of ARIA?'

Ask: 'If I am on a blood thinner, can I safely take these drugs? What are the alternatives?'

Ask: 'What is the protocol if I develop ARIA? Will we stop the drug temporarily or permanently? What are the chances of full recovery?'

Ask: 'How often will I need follow-up MRIs, and what symptoms should I watch for between scans?'

Ask: 'Are there any other medications I am taking that could interact with these infusions?'

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