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Lecanemab Has FDA Approval, But Alzheimer’s Patients Should Proceed With Caution

Neuroscientists now have tracked three deaths associated with clinical trials

As expected, the U.S. Food and Drug Administration recently approved lecanemab, an experimental antibody drug that may slow cognitive decline in Alzheimer’s patients.

However, lecanemab brings with it a whole host of side effects that raise questions. In fact, prior to the drug’s approval, the journal Science in late December published a report about the death of a third lecanemab clinical trial participant, a 79-year-old woman in Florida. The quick takeaway? “Multiple neuroscientists who reviewed the records at Science’s request believe her death was likely caused by the antibody, lecanemab,” the journal wrote.

There is great cause for caution and concern when it comes to lecanemab. In a Jan. 6 blog on the Alzheimer’s Information Bulletin, Neurology Associates’ Aaron Charlton reviewed the drug’s side effects. Here, we repost his observations:

Biggest Side Effects

In what follows I review the reported results from the [lecanemab] clinical trial. You can access the paywalled report here and … you can get the full paper for free here.

Brain Swelling (ARIA-E)

Excess fluid build up causes excess pressure on the brain. Symptoms of this problem include headaches, nausea, vomiting, seizures, drowsiness, visual disturbances and dizziness (if it doesn’t kill you or put you in a coma). In the trial, brain swelling occurred in 113 (12.6%) people who received the treatment but only 15 (1.7%) people in the placebo group. That’s a bad side effect and a high rate of occurrence.

Bleeding in the Brain (ARIA-H)

Another really bad side effect. These are very tiny releases of blood but they can add up if you have a lot of them. This issue affected 155 (17.3%) of the treatment group but only 81 (9.0%) of the placebo group.

Superficial Siderosis

A toxic, debilitating buildup of iron in the tissues between brain and skull. The buildup is caused by bleeding in the brain over time. It often manifests by abnormal uncoordinated movements and hearing loss. In the treatment group, this affected 50 (5.6%) patients but only 22 (2.5%) in the placebo condition.


These side effects are severe, unfortunate, and common. Patients and their family members should know the risks and weigh them carefully before leaping in. In many cases the drug caused much more harm than good. We all want to see Alzheimer’s disease cured, but the cost in terms of side effects is very high in this case. It’s definitely good to be cautious.

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