New Alzheimer's Drugs: What Caregivers Need to Know About Lecanemab and Donanemab

For decades, medications for Alzheimer's disease could only manage symptoms — helping with memory and behavior for a period of time — without touching the underlying disease process. That changed with the FDA approvals of lecanemab (brand name Leqembi) in 2023 and donanemab (brand name Kisunla) in 2024. These are the first drugs proven to slow the progression of Alzheimer's disease itself, not just the symptoms.

If your parent has been diagnosed with early Alzheimer's or mild cognitive impairment due to Alzheimer's, these treatments may come up at a specialist appointment. This guide explains what they are, who they are for, what the risks look like, and what caregivers are responsible for managing if a parent starts one of these drugs.

What These Drugs Actually Do

Lecanemab and donanemab belong to a class called anti-amyloid antibodies. Alzheimer's disease involves the accumulation of amyloid plaques in the brain — abnormal protein deposits that are associated with the death of brain cells. These drugs work by binding to amyloid and helping the immune system clear it.

In clinical trials:

• Lecanemab reduced cognitive decline by approximately 27% over 18 months compared to placebo
• Donanemab reduced cognitive decline by approximately 35% in patients with low-to-medium amyloid burden

This does not mean the drugs reverse Alzheimer's or restore lost memory. They slow how fast the disease progresses in people who are still in its early stages. For a caregiver watching a parent decline, 27–35% slower progression over 18 months is meaningful — it represents months of additional independence and cognitive function.

Who Is Eligible

These drugs are not for everyone with a dementia diagnosis. Eligibility requirements are specific and exclude many patients.

You must have early-stage disease. Both drugs are approved only for mild cognitive impairment (MCI) due to Alzheimer's or mild Alzheimer's dementia. Patients with moderate or severe Alzheimer's are not candidates — the disease has progressed too far for amyloid removal to provide benefit.

Amyloid must be confirmed. Amyloid pathology must be confirmed by either a PET scan (amyloid PET) or a cerebrospinal fluid (CSF) test. This is a diagnostic step that costs time and money and is not universally covered by insurance.

Genetic screening matters. People who carry two copies of the APOE4 gene variant (APOE4 homozygotes) face significantly higher risk of serious side effects and are generally advised against these treatments. APOE4 testing may be recommended before starting.

Certain conditions are exclusionary. Active bleeding in the brain, recent stroke, being on anticoagulants (blood thinners), and certain other medical conditions typically disqualify a patient. This is important for caregivers to know: a parent on warfarin or a direct oral anticoagulant (DOAC) like apixaban may not be eligible, or may face difficult conversations about stopping the blood thinner.

Medicare coverage. Medicare Part B covers both lecanemab and donanemab for eligible patients. Coverage includes the drug, the required MRI monitoring, and the infusion administration. However, Part B cost-sharing applies — if your parent does not have a Medigap supplement, they may face 20% coinsurance on each infusion and each MRI.

How the Treatment Works in Practice

Both drugs are given as intravenous infusions, not pills. This is a significant logistical consideration for caregivers.

Lecanemab (Leqembi): Infused every two weeks, indefinitely.

Donanemab (Kisunla): Infused every four weeks for up to 18 months (until amyloid is cleared on follow-up PET scan, then treatment stops).

Each infusion takes approximately one hour plus observation time. Your parent will need transportation to and from the infusion center at each visit. Over the course of treatment, this represents a substantial caregiving commitment — especially for lecanemab, which continues indefinitely.

Before starting treatment, a baseline MRI is required. Follow-up MRIs are scheduled at regular intervals during treatment (typically at weeks 4, 8, and 12, then less frequently). These MRIs monitor for a specific type of side effect described in the next section.

The Most Important Risk: ARIA

ARIA stands for Amyloid-Related Imaging Abnormalities. It is the primary safety concern with both lecanemab and donanemab, and it is the reason MRI monitoring is mandatory.

ARIA comes in two forms:

• ARIA-E (edema): Swelling in the brain or the fluid surrounding it
• ARIA-H (hemosiderin): Small areas of microhemorrhage (microscopic bleeding) in the brain

In clinical trials, ARIA occurred in approximately 21–35% of lecanemab patients and 24–36% of donanemab patients. Most cases were detected on MRI and caused no symptoms — or only mild, temporary symptoms like headache, dizziness, or confusion that resolved on their own.

However, severe symptomatic ARIA occurred in a small percentage of patients, and three deaths in clinical trials were associated with ARIA (though causation was complex). In real-world practice outside of trials, severe ARIA cases have also been reported.

What this means for caregivers:

You need to know the warning signs of symptomatic ARIA and report them to the prescribing neurologist immediately — not at the next scheduled appointment.

Call the neurologist or go to the emergency room if your parent develops:

• New or sudden confusion or disorientation
• Sudden worsening of memory or cognitive function
• Vision changes
• Headache that is new, severe, or different from their usual
• Dizziness or difficulty walking
• Nausea or vomiting (new onset during treatment period)
• Weakness on one side of the body
• Seizure

These symptoms after an infusion — or in the weeks following one — should be taken seriously. The drug may need to be paused while the ARIA resolves on a follow-up MRI.

How Anticoagulants Complicate the Decision

This is one of the most important practical issues caregivers encounter. Many elderly patients with heart conditions are on blood thinners — warfarin, apixaban (Eliquis), rivaroxaban (Xarelto), or aspirin. ARIA involves brain microbleeds. Adding a blood thinner significantly increases the risk of those bleeds becoming larger and more dangerous.

The clinical trials for both drugs excluded patients on anticoagulants. Post-approval guidance from neurologists is cautious: these drugs are generally not recommended for patients who need ongoing anticoagulation for conditions like atrial fibrillation.

If your parent is on a blood thinner for AFib and is otherwise eligible for lecanemab or donanemab, this creates a difficult tradeoff: stopping the anticoagulant to pursue Alzheimer's treatment increases stroke risk. The family needs to have an explicit conversation with the cardiologist and neurologist together about which risk is greater given the specific clinical picture.

Do not navigate this tradeoff without both specialists engaged. It is exactly the kind of cross-specialty medication decision that falls apart when specialists operate in silos.

Questions to Ask the Neurologist Before Deciding

Before agreeing to start one of these treatments, caregivers should walk into the appointment prepared:

1. "Is my parent's disease stage actually early enough to benefit from this?"
2. "What does the amyloid confirmation test involve and what does it cost?"
3. "What is her APOE4 status and how does that affect her risk?"
4. "She is on [blood thinner] — is she actually eligible given that?"
5. "What are the transportation requirements for infusions?"
6. "What is her Part B cost-sharing for each infusion and each MRI? Does she have a Medigap supplement that covers it?"
7. "What symptoms should I call you about immediately after an infusion?"
8. "If she develops ARIA, will you stop the drug or pause it?"
9. "What does success look like? How will we know if this is working?"

What the Treatment Cannot Do

Being clear-eyed about the limitations of these drugs is important before committing to the logistical and financial demands of the treatment. These drugs:

• Do not restore lost memory or function. They slow future decline; they do not reverse what has already happened.
• Do not work for everyone who meets the criteria. A subset of patients show no slowing of decline even with confirmed amyloid clearance.
• Require a significant logistical commitment. Every two or four weeks, indefinitely (for lecanemab), is a real burden on caregiver time and family finances (for cost-sharing not covered by insurance).
• Carry real risk in the real world. Clinical trial populations are carefully screened. Real-world patients have more comorbidities and take more concomitant medications than trial participants, meaning real-world ARIA rates and severity may differ from trial data.

The decision to pursue these treatments is not automatically the right decision for every eligible patient. A parent who is already frail, lives far from an infusion center, or is on medications that increase risk may be better served by optimizing their current symptom management, safety at home, and quality of life.

Integrating Alzheimer's Treatment Into a Complex Medication Regimen

If your parent starts lecanemab or donanemab, their overall medication management becomes significantly more complex. You now have:

• An IV medication with a schedule that must be tracked
• Required MRI appointments to coordinate
• Symptom monitoring responsibilities between infusions
• Interaction considerations with all their existing medications
• A neurologist who needs to stay in contact with the cardiologist, primary care physician, and any other specialists

This is exactly the situation where a complete, up-to-date Master Medication Record — shared with every provider — prevents dangerous fragmentation. The neurologist who prescribes lecanemab needs to know about every other drug your parent takes. The cardiologist needs to know an anti-amyloid drug is being added. A complete medication record makes those cross-provider conversations accurate and fast.

Managing an elderly parent's medications through a complex new treatment is one of the highest-stakes caregiving responsibilities there is. Our Medication Management Kit for Caregivers includes a Master Medication Record template, specialist appointment preparation guides, and drug interaction reference tools — everything designed to help you stay organized when the medical picture is this complicated.