Spanish scientists hail breakthrough in Alzheimer’s treatment as debate grows over safety, costs, and benefits

A NEW treatment for Alzheimer’s slowed the disease’s progression “for the first time in history,” Spanish scientists said – but the breakthrough remains mired in controversy over a spate of practical issues and safety concerns.

According to a series of studies published on Monday in The Lancet medical journal, experimental drugs donanemab and lecanemab successfully reduced cognitive decline in Alzheimer’s patients by 35% and 27%, respectively, during a clinical trial involving nearly 3,000 participants.

Juan Fortea, head of the Neurobiology of Dementia Department at Barcelona’s Sant Pau Institute and co-author of one of the studies, hailed the findings as a “paradigm shift.”

He told El Pais: “We have not cured the disease, but this is the first time in human history we successfully slowed the progression of Alzheimer’s.”

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Both medications have already won full regulatory approval in countries including the United States, Japan, China, and Australia.

The European Medicines Agency (EMA), however, only cleared lecanemab in 2024 after a fraught two-year review process, while donanemab remains under scrutiny.

The scientific community is divided on the new treatment, with critics citing dangerous side effects, high costs, and modest efficacy.

In 2022, two trial participants died of cerebral haemorrhages while on lecanemab. A medical team involved in the trial told Science magazine that at least one of the patients would have lived had she not been taking the drug.

Overall, serious adverse effects were reported for one in 65 donanemab patients, and one in 300 lecanemab patients.

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The treatment’s steep costs are another sticking point, with estimates pointing to an average €24,000 per year to treat a single patient with a full course of donanemab and lecanemab.

In October last year, the NHS blocked donanemab from widespread use in UK hospitals over cost.

Finally, the Lancet studies suggest the medications would only work for about 5% of patients, and only when Alzheimer’s is detected at an early stage.

Detractors have also questioned the studies’ conclusions, demanding clarity on how the mild delays in cognitive decline would actually impact patients’ lives – and whether benefits would outweigh the treatment’s potential risks and pitfalls.

But Fortea dismissed part of the criticisms as mere prejudice and outdated concerns.

He said: “If [Alzheimer’s] weren’t such a prevalent condition – if it didn’t put pressure on the healthcare system, increase costs, or require changes in procedures – much of the controversy wouldn’t exist.

“Were it a rare disease, we have little doubt that approval would have come swiftly and without any controversy.”

Alberto Lleó, head of Neurology at Sant Pau Institute, added this was “just the beginning.”

“A further 138 drugs are currently being researched, and they are just the first of many more to come,” he said.

In 2020, around 55 million people were estimated to be living with dementia worldwide, with Alzheimer’s disease accounting for roughly 70% of cases.

A World Health Organisation (WHO) report estimated the figure would soar to 139 million by 2050 unless breakthroughs were achieved in prevention and care.

Alzheimer’s disease results from a complex combination of genetic, biological, and environmental factors – but a hallmark of the condition is the build-up of a protein known as amyloid-beta on neurons in the brain.

Donanemab and lecanemab work by targeting amyloid-beta plaques on the neurons, binding with the protein before removing it from the brain.

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Fortea stressed that while the drugs do not cure the disease, their impact is real.

“Patients are more independent and have a higher quality of life, because we are slowing down a condition that causes severe disability,” he said.

“We are not curing the disease. Patients still deteriorate, but they do so more slowly.”

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