What are the benefits and safety concerns of using intravenous (IV) lecanemab for the treatment of Alzheimer's disease (AD)?

Explaining Lecanemab Benefits and Safety to Patients and Families

Lecanemab is an IV medication that can slow down memory and thinking decline by about 30% in early Alzheimer's disease, but it requires careful monitoring because it can cause brain swelling or bleeding that is usually mild but occasionally serious or even fatal. 1

What Lecanemab Does (The Benefits)

How It Works:

• Lecanemab removes the sticky amyloid protein clumps that build up in the brain and damage memory cells in Alzheimer's disease 1, 2
• Think of it like cleaning out the "garbage" that's clogging up the brain's ability to function properly 2

What Improvement Looks Like:

• The medication slows down—but does not stop—the worsening of memory and thinking problems by approximately 30% over 18 months 3, 4
• This means patients may maintain their ability to do daily activities (like managing finances, cooking, or driving) for several months longer than without treatment 5
• Family members report less burden from caregiving when patients receive lecanemab 5
• Patients and families report better quality of life compared to those not receiving treatment 5

Important Limitations to Understand:

• This medication only works for people in the early stages of Alzheimer's (mild memory problems or mild dementia), not advanced disease 1
• You must have a test proving amyloid protein is present in the brain before starting (either a brain scan, spinal fluid test, or blood test) 1, 6
• The medication slows decline but does not reverse damage already done or cure Alzheimer's disease 2, 4

The Safety Concerns (What Can Go Wrong)

Brain Swelling and Bleeding (ARIA):

The most important risk is called ARIA—"Amyloid-Related Imaging Abnormalities"—which means swelling or small bleeds in the brain that show up on MRI scans 1:

• Brain swelling (ARIA-E) happens in about 13% of patients (roughly 1 in 8 people) 6, 7

  • Most people have no symptoms, but some experience headaches, confusion, vision changes, dizziness, or difficulty walking 1
  • Usually occurs in the first 3-6 months of treatment 6, 7
  • Most cases are mild and resolve on their own, but serious cases can occur 1, 7

• Brain bleeding (ARIA-H) with small hemorrhages happens in about 16-17% of patients 6, 7

  • Usually these are tiny "microbleeds" that cause no symptoms 7
  • Larger brain bleeds (over 1 cm) occurred in less than 1% of patients, and a few have been fatal 1

Who Is at Higher Risk:

Your genetic makeup significantly affects your risk 1:

• People with two copies of the APOE ε4 gene (about 15% of Alzheimer's patients) have the highest risk: 45% chance of ARIA, with 9% experiencing symptoms 1, 7
• People with one copy have moderate risk: 19% chance of ARIA, with 2% experiencing symptoms 1, 7
• People with no copies have lowest risk: 13% chance of ARIA, with 1% experiencing symptoms 1, 7

We strongly recommend genetic testing before starting treatment so you understand your personal risk 1

Other Important Safety Concerns:

• Infusion reactions (like allergic reactions) occur in about 25% of patients during or shortly after the IV infusion, causing symptoms like fever, chills, or nausea 7, 8
• Blood thinners are dangerous with lecanemab—patients on warfarin, Eliquis, or similar medications should not receive this treatment due to increased bleeding risk 2
• Three deaths from brain bleeding have occurred in patients taking lecanemab along with blood thinners or clot-busting medications 7

What Treatment Involves (The Practical Details)

Treatment Schedule:

• IV infusion every 2 weeks for at least 18 months, each taking about one hour 1
• After 18 months, may continue every 2 weeks or switch to monthly infusions 1
• Must be given at a medical facility equipped to handle reactions 6

Required Monitoring:

• Brain MRI scan before starting to check for pre-existing bleeding or other problems that would make treatment unsafe 1
• Brain MRI scans at specific times during treatment (before the 5th, 7th, and 14th infusions—roughly at 3,4, and 7 months) to watch for brain swelling or bleeding 6, 1
• Additional MRI immediately if you develop symptoms like severe headache, confusion, vision changes, or difficulty walking 1
• Enrollment in a Medicare registry if using Medicare insurance 6

When Treatment Must Be Stopped:

Treatment is temporarily or permanently stopped if MRI shows 1:

• Moderate to severe brain swelling
• Large brain bleeds
• Multiple small bleeds
• Any symptomatic brain changes

Common Pitfalls and Important Caveats

Misconceptions to Avoid:

• This is not a cure—it only slows decline, and Alzheimer's will continue to progress 2, 4
• Benefits are modest—about 30% slowing, which translates to a few months of preserved function 3, 4
• The medication only works if started early; it cannot help people with moderate or advanced dementia 1

Critical Safety Points:

• Never ignore new symptoms like headache, confusion, or vision changes—these could indicate dangerous brain swelling requiring immediate medical attention 1
• Stroke-like symptoms could actually be brain swelling from the medication, not a stroke—doctors must check MRI before giving clot-busting drugs 1
• Cannot skip MRI monitoring—these scans are mandatory for safety, not optional 6, 1

Access and Practical Barriers:

• Treatment requires specialized dementia centers with expertise in managing these medications 6
• Not all insurance plans cover the medication, and out-of-pocket costs can be substantial 6
• The time commitment is significant: biweekly infusions plus multiple MRI scans over many months 1

The Bottom Line for Decision-Making

Lecanemab offers a modest but meaningful benefit in slowing early Alzheimer's decline, preserving independence for several additional months, but this comes with real risks of brain swelling and bleeding that require intensive monitoring. 1, 7, 5 The decision should weigh:

• Your current disease stage (only works in early disease) 1
• Your APOE ε4 genetic status (higher risk if you have the gene) 1
• Your ability to commit to frequent infusions and MRI monitoring 6, 1
• Whether you take blood thinners (which makes treatment unsafe) 2
• Your personal values about accepting risk for modest benefit 2