In 2023, the Food and Drug Administration (FDA) approved lecanemab, a new therapy for Alzheimer’s disease. This approval brought hope to many patients and doctors since lecanemab is the first drug of its kind that actually slows the progression of the disease, not just treats its symptoms.
However, during clinical trials, some patients experienced side effects like brain swelling and bleeding, which made some doctors and patients nervous about its use. These concerns left many wondering if the risks outweighed the benefits.
To better understand the real-world safety of lecanemab, researchers at Washington University School of Medicine in St. Louis decided to look into their own patients’ experiences. They studied 234 patients who received lecanemab treatments at their Memory Diagnostic Center, a clinic that focuses on treating people with dementia.
Their findings, which were published in JAMA Neurology, were mostly reassuring. Only about 1% of their patients experienced severe side effects that required hospitalization, which is similar to the rates seen in clinical trials. Importantly, these events were found to be manageable with proper medical care.
The researchers also found that the stage of Alzheimer’s disease made a big difference. Patients who were in the very early stages of the disease, with only mild symptoms, had the lowest risk of experiencing side effects.
In fact, only 1.8% of these early-stage patients had any adverse reactions to the drug. On the other hand, for patients with more developed symptoms, the risk jumped to 27%. This suggests that lecanemab is safest and most effective for people who are diagnosed early.
Lecanemab works by clearing out amyloid plaques from the brain. These plaques are clumps of proteins that build up in the brains of people with Alzheimer’s and are thought to play a major role in the disease’s progression.
By removing these plaques, lecanemab has been shown to extend a patient’s ability to live independently by around 10 months, according to recent studies. Because of how it works, doctors recommend starting lecanemab as early as possible, before symptoms become severe.
Despite its benefits, there are still risks associated with lecanemab, primarily related to something called amyloid-related imaging abnormalities (ARIA). ARIA shows up on brain scans as swelling or small amounts of bleeding.
In the clinical trials for lecanemab, about 12.6% of participants experienced ARIA, though most of these cases were mild and didn’t cause any noticeable symptoms. In fact, they were often only discovered during routine brain scans.
About 2.8% of patients did have symptoms like headaches, dizziness, confusion, or nausea, and in very rare cases—about 0.2% of patients—ARIA has been linked to deaths.
At Washington University’s Memory Diagnostic Center, the doctors closely monitor patients with regular brain scans to catch these changes early. If ARIA is detected, they stop the treatment right away to prevent it from getting worse. In very rare severe cases, patients are treated with steroids to reduce inflammation.
The clinic’s doctors say that understanding these risks and managing them properly can help make the treatment much safer. Dr. Barbara Joy Snider, a professor of neurology and co-author of the study, emphasized that fear of side effects sometimes keeps patients from getting treated early.
She hopes the results of this study will help ease some of those fears and encourage earlier treatment, which seems to be both safer and more effective.
Dr. Suzanne Schindler, another co-author of the study, agreed. She said that most patients in their clinic tolerate lecanemab well and that the risks are lower for people who start the treatment early, before symptoms get worse. She believes that this new data might help patients and their families feel more comfortable discussing the drug with their doctors.
Since its approval, Washington University’s Memory Diagnostic Center has been giving lecanemab to patients through infusions every two weeks. These are done in specialized centers where patients are closely watched.
Regular brain scans are part of the care routine to catch any swelling or bleeding as early as possible. If any issues are found, doctors take action right away to prevent serious problems.
The results of this real-world study are important because they show that with proper monitoring and early treatment, lecanemab can be a safe and effective way to slow the progression of Alzheimer’s disease.
While side effects like brain swelling and bleeding are possible, they are rare and often manageable. For people in the very early stages of Alzheimer’s, the benefits seem to clearly outweigh the risks, giving patients and their families a new option for fighting this devastating disease.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
The research findings can be found in JAMA Neurology.
Copyright © 2025 Knowridge Science Report. All rights reserved.
