The European Commission announced on Tuesday the approval of the antibody lecanemab to treat Alzheimer's.

Lecanemab is intended for treatment in the early stages and is the first medication of its kind to be approved in the European Union, the Commission said. 

It is the first time the European Commission has authorized Alzheimer's therapy that targets the underlying disease processes, rather than just the symptoms. 

However, experts say that only a very small portion of Alzheimer's patients are eligible for this therapy.

Lecanemab is sold under the brand name Leqembi. The drug is already authorized in the United States, UK and Japan.

What makes the treatment different?

Previous Alzheimer's therapies have only treated symptoms of the disease, not causative processes in the brain. 

The lecanemab antibody is directed against amyloid deposits (a protein) in the brain and is intended to slow down the progression of the disease. 

The main measure of efficacy of lecanemab was the change in cognitive and functional symptoms after 18 months, which was measured using a dementia rating scale.

The scale ranges from 0 to 18, with higher scores indicating greater impairment. 

Patients treated with lecanemab showed a slightly lower increase in the score after 18 months (1.22 compared to 1.75).  This indicated a slower cognitive decline, the European Medicines Agency (EMA) said.

However, the therapy cannot cure the disease, and a drug to cure Alzheimer's is still not in sight.

Why can't all Alzheimer's patients receive lecanemab?

If the amyloid deposits have already caused irreversible damage to the brain, slowing their growth will not reverse damage. It is only approved for treatment of mild cognitive impairment in early stages of Alzheimer's

It is also restricted to patients with a specific gene variant that will not cause side effects like swelling and bleeding in the brain. 

Out of 1.2 million estimated Alzheimer's sufferers in Germany, only a small proportion are eligible for the therapy, dpa reported, citing experts from the German Centre for Neurodegenerative Diseases (DZNE). 

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Edited by: Wesley Rahn