Leqembi vs. Kisunla: Who Qualifies for the New Alzheimer's Drugs
Leqembi (lecanemab) and Kisunla (donanemab) are anti-amyloid drugs for people with early Alzheimer's disease, meaning mild cognitive impairment or mild dementia, whose brains show amyloid build-up on a scan or test.
Leqembi (lecanemab) and Kisunla (donanemab) are anti-amyloid drugs for people with early Alzheimer's disease, meaning mild cognitive impairment or mild dementia, whose brains show amyloid build-up on a scan or test. They modestly slow decline but don't stop it, and they need regular MRI monitoring because of a risk of brain swelling or bleeding.
What do Leqembi and Kisunla actually do?
Both are antibodies that help the immune system clear amyloid, the sticky protein that builds up in plaques in Alzheimer's. In their main trials, people on the drugs declined more slowly than people on placebo over about 18 months, by roughly 27% for lecanemab and up to about 35% for donanemab (in people with lower tau levels) on the main measures used.
What that means day to day is debated. Supporters point out that a few extra months at a milder stage can be worth a lot to a family. Skeptics say the difference is small enough that many patients and carers won't notice it. Both views are reasonable. These drugs are a real step, not a cure.
Who qualifies for the new Alzheimer's drugs?
Generally, a person needs all of these:
- A diagnosis of mild cognitive impairment or mild dementia due to Alzheimer's
- Confirmed amyloid, from a PET scan, a spinal fluid test or a validated blood test
- A recent brain MRI without too many small bleeds or other red flags
- No blood thinners or bleeding disorders that would raise the risk too much (this is assessed case by case)
They are not approved for moderate or advanced Alzheimer's, or for other dementias like vascular or Lewy body. That's one reason an accurate diagnosis matters, and our guide to the types of dementia explains why the label isn't just paperwork. Blood tests are making the amyloid step easier, and we covered what they can and can't tell you in blood tests for Alzheimer's.
The FDA prescribing information also recommends testing for the APOE4 gene before starting, because people with two copies have a much higher risk of side effects.
How are Leqembi and Kisunla different?
The biggest differences are about the schedule.
Leqembi can be started either as an IV infusion every two weeks or as a weekly injection under the skin (Leqembi Iqlik) that can be given at home. The FDA approved the at-home starting option in July 2026. After about 18 months, maintenance can move to an IV infusion every four weeks or stay on weekly injections. What's available and covered can vary, so check with your doctor and insurer.
Kisunla is an IV infusion every four weeks, each taking about 30 minutes. In its trial, people could stop treatment once scans showed amyloid had been cleared, which may mean fewer total infusions for some.
Rates of brain swelling were somewhat higher with donanemab in trials, though in 2025 the FDA approved a more gradual starting dose to reduce that. Head-to-head trials haven't been done, so nobody can honestly tell you one is better overall.
What are the side effects and risks?
The main one is ARIA, short for amyloid-related imaging abnormalities. It shows up on MRI as swelling or tiny bleeds in the brain. Most people with ARIA have no symptoms and it settles on its own, but some get headaches, confusion or vision changes, and rare cases have been severe or fatal. Infusion reactions such as fever or chills are also common, especially early on.
That's why treatment comes with a schedule of MRIs, usually several in the first months. Make sure you understand who to call, day or night, if new symptoms appear.
What should you ask your doctor?
- Based on my tests, am I a candidate, and how sure are we that this is Alzheimer's?
- What's my APOE4 status, and how does it change my risk?
- How often will I need infusions and MRIs, and where?
- What will it cost after insurance or Medicare?
- How will we tell if it's helping, and when would we stop?
The logistics are real. Infusions every few weeks plus MRIs can be a lot for someone who no longer drives. If you're weighing it up, factor in who will get them there, and whether some follow-up visits can be done by video. Our telehealth setup guide can help with that part.
Frequently asked questions
- Who qualifies for Leqembi or Kisunla?
- People with mild cognitive impairment or mild dementia caused by Alzheimer's disease, with amyloid confirmed by a PET scan, spinal fluid test or, increasingly, a validated blood test. Doctors also check MRI results, bleeding risk and other medications.
- Do Leqembi and Kisunla cure Alzheimer's?
- No. In trials they slowed decline by roughly a quarter to a third over about 18 months. They do not stop the disease or restore lost memory.
- What is ARIA?
- ARIA stands for amyloid-related imaging abnormalities: swelling or small bleeds in the brain seen on MRI. Most cases cause no symptoms, but some are serious. Risk is higher in people with two copies of the APOE4 gene.
- What is the main difference between Leqembi and Kisunla?
- Leqembi can be started as an IV infusion every two weeks or as a weekly at-home injection under the skin, with maintenance options after about 18 months. Kisunla is an IV infusion every four weeks, and doctors can consider stopping once scans show amyloid has cleared.
