Lecanemab (Leqembi) is a medicine given to slow the progression of mild Alzheimer's disease (AD). This medicine reduces clumps of proteins called amyloid-beta proteins that play a key role in AD. Reducing amyloid-beta proteins in the brain modestly slows memory and thinking decline from AD.

Lecanemab is for people who have early symptomatic AD. A recent trial of the medicine showed that taking lecanemab over 18 months slowed the rate of cognitive decline. It's not yet known whether the medicine helps in other ways such as slowing development of AD in people without symptoms of memory loss.

Lecanemab is given as an IV infusion every two weeks. Your care team watches for side effects and asks you or your caregiver how your body reacts to the medicine.

Because lecanemab is a new medicine, there is still much to learn about it. Some people who take lecanemab have side effects such as:

• Dizziness.
• Headache.
• Visual changes.
• Worsening confusion.
• Swelling or bleeding in the brain.
• Brain shrinkage.
• Rarely, death.

Lecanemab is not helpful for people with full cognitive function or later stages of AD. The medicine does not prevent or cure AD. Your health care team helps you decide if lecanemab is an option for you.

The medicines you take for other conditions and your health history may affect whether you can take lecanemab. A history of cancer or bleeding in your brain or use of anticoagulant drugs, such as warfarin (Jantoven) or apixaban (Eliquis), may prevent you from taking lecanemab.

Also, people who carry a certain form of a gene known as APOE e4 appear to have a higher risk of serious side effects when they take lecanemab. The U.S. Food and Drug Administration recommends being tested for this gene before starting treatment with lecanemab.

If you take lecanemab, you need a brain MRI before beginning treatment. Then you have regular MRI scans to check for brain bleeds. If your side effects are severe, you may need anti-seizure medicines or care in a hospital. You also may have to stop taking the medicine.