A medicine hailed as “the beginning of the end for dementia” might cause dangerous brain bleeding, according to a leading Alzheimer’s researcher.

Lecanemab, which has been tested across the United States, was proven to significantly delay the progression of the disease. Professor John Hardy, a top dementia researcher at University College London (UCL) whose original study opened the path for the development of lecanemab, made headlines last week when he stated that he thought the treatment would be accessible on the National Health Service (NHS) within a year.

One in ten participants in the most recent lecanemab trial experienced amyloid-related imaging abnormalities (ARIA), also known as brain swelling. One in six individuals developed brain hemorrhages.

Patients who showed signs of brain enlargement or bleeding, which were detected by MRI scans administered every three months as part of the trial, were removed from the medication.

Prof. Hardy contends that the potential danger posed by these side effects necessitates regular scans for anyone receiving lecanemab, which is administered every two weeks.

It must be monitored with an MRI, he says. This raises the therapy’s load and price.

Nearly one million Britons suffer from dementia, with Alzheimer’s disease being the most prevalent kind. The accumulation of amyloid, a neurotoxin, in the brain is believed by many specialists to be the cause.

Prof. Hardy first proposed the hypothesis in the 1990s. Several amyloid-targeting medicines have been evaluated, but none have had a significant impact until lecanemab. In clinical trials, people with Alzheimer’s who received lecanemab experienced a 27% slower deterioration in cognitive ability over 18 months than patients who did not receive the medicine.

Due to the risk of cerebral hemorrhage, it may not be able to implement lecanemab safely on the NHS, according to some specialists.

Robert Howard, professor of geriatric psychiatry at the UCL Institute of Mental Health, stated, “It is unclear whether the advantages justify the risk of adverse consequences.

This week, complete trial findings for lecanemab will be presented.