AN ALZHEIMER’S drug hailed as a ‘miracle’ medicine for dementia may cause life-threatening brain bleeds in a third of patients who take it, warns a new study.
The medication has previously been shown to slow down the memory-robbing illness by 35 per cent – better than any previous treatments.
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But some experts say the side effects of the drug called donanemab may outweigh its benefits.
It was given the green light by UK drug regulators, the Medicines and Healthcare Products Regulatory Agency (MHRA), in October 2024.
This meant it was deemed safe and effective for people in the early stages of the disease and could be prescribed privately in Britain.
But the National Audit Office (NAO), the UK’s spending watchdog for the NHS, said the benefits of the drug were “too small” to justify the cost to the health service.
Donanemab is the second drug that’s been found to slow the progress of Alzheimer’s disease after lecanemab.
Now, new research from the company that produces donanemab has confirmed the findings of early studies that suggested the drug’s deadly risks.
Scientists at pharmaceutical firm Eli Lilly found the monthly jab more than doubled the risk of deadly bleeds in 3,000 patients who received it over the course of three years.
The drug was found to trigger amyloid-related imaging abnormalities, or ARIA, which causes inflammation of the blood vessels in the brain.
The condition usually has no symptoms and goes away on its own, but can in some cases prove more serious.
Of the patients who took the drug, 31 per cent were found to have brain bleeds.
For those taking the placebo, the risk was just 1.9 per cent.
One in four of the patients suffered brain swelling and nearly six per cent experienced symptoms related to this, including confusion, dizziness and nausea.
A total of 79 patients had to stop taking the medication because of the severe side effects.
The patients who took part in the study were aged 60 to 85 and presented with early Alzheimer’s disease.
They were then given the drug over two separate three-year trials.
For those with the most serious ARIA cases, symptoms occurred within the first three months.
Pharmaceutical companies must disclose all clinical trial results, even if they’re negative, within a year of the trial’s end date.
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“While ARIA-E events were typically transient and asymptomatic, ARIA can be serious, life threatening, or fatal,” wrote lead researchers Dr John Sims and Dr Jennifer Zimmer, Eli Lilly’s senior medical director and associate vice president.
“Therefore, safety monitoring is necessary with donanemab.”
Prof Tom Dening, Professor of Dementia Research, School of Medicine, University of Nottingham, told Sun Health he wasn’t surprised by the findings.
He said: ” I imagine that the safety data was made available to the MHRA for them to make their decision, and maybe the delay has been that it takes a while to get a scientific article published in a journal.
“This is because of possible delays at various stages, e.g. in scientific peer review, if revisions are required, and sometimes between the paper being accepted and being published.
“I see that this paper was accepted in December 2024 but only published today.”
Other major Alzheimer’s breakthroughs
While experts have warned that dementia diagnoses in England have reached record numbers, there have been a number of recent advances against brain robbing diseases.
From “game-changing” drugs gaining approval to blood tests that can spot the condition years before symptoms, here are other major Alzheimer’s breakthroughs.
- A “game-changing” Alzheimer’s drug called donanemab, that slows mental decline by up to 60 per cent has been approved in the United States. A UK decision on whether the drug will become available to patients in the UK with early symptoms is expected imminently.
- A blood test that detects Alzheimer’s up to 15 years before symptoms emerge is set to be made free on the NHS within a year. The new test is cheaper, easier and at least as accurate as the current diagnosis options and works by measuring levels of a protein in the blood called p-tau217.
- Researchers have developed a first-of-its-kind test that could predict dementia up to nine years before a diagnosis, with 80 per cent accuracy. It involves analysing network of connections in the brain when it’s in “idle mode” to look for very early signs of the condition.
- A woman who has evaded Alzheimer’s disease despite half her relatives getting it could hold the clues to how to prevent it, with scientists pinpointing a particular gene which they think could help prevent Alzheimer’s from progressing.
Prof Dening added it’s unclear at this point in time whether the findings will impact donanemab’s us in the UK.
He said: “Possibly, clearly monitoring for side-effects is important and potentially expensive.
“Although, I can’t see NICE ever approving donanemab as I can’t see how the cost of the drug, the cost of administering it and the cost of monitoring can ever be recouped by reduced health service demand.
“I think NICE has made the right decision.”
A 2024 report commissioned by the Alzheimer’s Society estimates that around one million people in the UK have dementia.
This is projected to increase to 1.4 million by 2040.
Dr Richard Oakley, Associate Director of Research and Innovation at Alzheimer’s Society, said: “Donanemab is one of a number of disease-modifying therapies offering a new horizon of hope in the fight against dementia.
“But as with any new treatment it’s crucial we understand the associated risks to ensure it is effective and safe.
“Donanemab is currently only available privately in the UK and we await a final decision from NICE later this year as to whether it can be provided through the NHS.
“In the meantime, we must not forget the need to support the around one million people living with dementia in the UK – a third of whom don’t have a diagnosis and are unable to access existing treatments and support that can help with managing symptoms.
“New treatments are an important catalyst for change but are just one piece of the puzzle.”
How to reduce your risk of dementia
There’s currently no cure for dementia, but there things you can do to reduce your risk.
Evidence suggests the following lifestyle choices can help stave off the condition.
Do physical exercise – Exercise can help keep the brain healthy by increasing blood flow and oxygen supply, stimulating the growth of new brain cells, and protecting brain function.
Drink less alcohol – Drinking too much alcohol can cause the parts of the brain that control memory to shrink.
Don’t smoke – Smoking increases the risk of developing dementia because it can damage blood vessels, reduce oxygen levels in the blood, and cause inflammation and stress in cells.
Stay mentally well and socially active – Social contact can help build cognitive reserve, which is the brain’s ability to resist the effects of Alzheimer’s disease.
Protect your eyesight and hearing – Protecting your eyesight and hearing can help reduce your risk of developing dementia because there’s a link between sensory loss and dementia.
Protect your head – Traumatic brain injuries are caused by a blow or jolt to the head – especially when the person is knocked out unconscious. These can start a process in the brain where the substances that cause Alzheimer’s disease build up around the injured area. Wear protective headgear in situations where there is a higher-than-normal risk of head injury.
Source: Alzheimer’s Society
