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Alzheimer's: New drug can reduce disease symptoms by up to 35%

The world is "on the cusp of a first generation of treatments for Alzheimer's disease", after a new drug was found to slow cognitive and functional decline.

Results of a study, released in a preliminary form by drug maker Eli Lilly, show their drug donanemab reduced the rate of cognitive decline of Alzheimer's patients in a trial by between 27 and 35%.

Those on the drug were also better able to maintain normal daily activities than patients not receiving it.

"This result confirms that we are now entering the treatment era of Alzheimer's disease," said Dr Cath Mummery, clinical lead for the Cognitive Disorders Clinic, at the National Hospital for Neurology and Neurosurgery in London.

Six months ago, drug firm Esai announced its drug called lecanemab showed similar effectiveness in slowing the progression of Alzheimer's.

The drugs, while potentially game-changing for Alzheimer's, have their drawbacks.

Two and possibly a third patient of the 1,700 participants in the donanemab trial died from brain swelling after receiving the medicine.

Similar events including bleeding on the brain were seen in the trial of lecanemab, although it was difficult to establish a direct connection to the medicine itself.

Both drugs are synthetic antibodies, mimicking those made by our immune system, and engineered to target amyloid, a "sticky" junk protein that builds up in the brains of people with Alzheimer's.

The drugs showed the ability to completely clear the build-up of amyloid and this is believed to be the reason for their effectiveness.

But the effects are, for the length of these trials at least, modest. No drug has yet been shown to stop, let alone reverse the impacts of Alzheimer's.

They do however, show that after years of failure, Alzheimer's research is on the right track.

"We're now on the cusp of a first generation of treatments for Alzheimer's disease, something that many thought impossible only a decade ago," said Dr Susan Kolhaas of Alzheimer's Research UK.

Another major challenge is cost.

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Antibody medicines are very expensive to make - in the US, treatment with lecanemab costs around $26,500 (£21,000) a year.

In addition, they have to be administered monthly via an IV drip and require regular check-ups in a brain scanner.

"This news underlines the urgency of preparing the NHS to make these treatments available should regulators deem them safe and effective," said Dr Kolhaas.

Lecanemab was approved by the US drug regulator in January. A decision in Europe is expected in 2024.

Regulators will make a decision on this donanemab once full trial data has been released later this year.