Breakthrough drug marked as 'beginning of the end for dementia' which ails a million Britons in doubt over brain bleed risks, expert warns

Breakthrough dementia drug Lecanemab was hailed as 'beginning of the end' But it's future cast in doubt over risk of brain bleeds Alzheimer's experts warned One in ten patients in the most recent lecanemab trial suffered brain swelling An one in six experienced brain bleeds which could hike the costs of the drug

A breakthrough drug hailed as ‘the beginning of the end for dementia’ can trigger dangerous brain bleeds, a top Alzheimer’s expert has warned.

Lecanemab, which has been trialed across America, was found to drastically slow the disease’s progression. And last week, Professor John Hardy, a world-leading dementia researcher at University College London (UCL) – whose original research paved the way to creating lecanemab – made headlines when he said he hoped the drug would be available on the NHS in a year.

But speaking to The Mail on Sunday, he warned that prescribing lecanemab has risks which could dramatically hike its costs.

One in ten patients in the most recent lecanemab trial suffered swelling in the brain, a condition known as amyloid-related imaging abnormalities, or ARIA. One in six experienced brain bleeds.

While only a small percentage of patients suffered symptoms such as headaches and dizziness, any who showed signs of brain swelling or bleeding – which were picked up through MRI scans carried out every three months as part of the trial – was taken off the drug.

Lecanemab, which has been trialed across America, was found to drastically slow the disease’s progression (file photo)

Almost one million Britons have dementia, with Alzheimer’s being the most common form. Many experts believe it is triggered by a build up of amyloid, a toxic protein, in the brain (file photo)

Prof Hardy argues the potential danger posed by these side effects means anyone taking lecanemab – which is given in a fortnightly jab – would also need scans regularly.

‘It needs to be monitored by MRI,’ he says. ‘This increases the burden and expense of the therapy.’

Almost one million Britons have dementia, with Alzheimer’s being the most common form. Many experts believe it is triggered by a build up of amyloid, a toxic protein, in the brain.

The theory was first proposed by Prof Hardy in the 1990s. Several drugs which target amyloid have been tested but none have had a real impact until lecanemab. Trials showed that Alzheimer’s patients given lecanemab saw their cognitive abilities decline 27 per cent less over 18 months than patients who did not take the drug.

However, some experts say that, with the risk of brain bleeding, it may not be possible to roll out lecanemab safely on the NHS.

‘It’s not clear if the benefits are enough to warrant the risk of side effects,’ said Robert Howard, professor of old age psychiatry at UCL Institute of Mental Health.

Full trial results for lecanemab will be presented this week.