New Alzheimer’s drugs can shrink brain, scientists warn

THE Alzheimer’s drugs touted as a turning point in the fight against the disease can cause the brain to shrink, scientists have warned.

Lecanemab and donanemab are two drugs that have been hailed as an Alzheimer’s breakthrough.

Data from the companies making the drugs, Eisai and Eli Lilly, respectively, shows a 27 per cent and 35 per cent slowing of cognitive decline in people with Alzheimer’s compared to a placebo. But experts have raised concerns about side-effect data, which shows the drugs can cause the brains of patients to shrink by as much as the volume of three teaspoons.

Lecanemab has been given Food and Drug Administration (FDA) approval in the US but with a “black-box warning” that indicates the drug comes with a risk of extreme adverse effects.

A decision on the drugs by the UK Medicines and Healthcare products Regulatory Agency (MHRA) is expected as soon as next week.

Prof Rob Howard, of the University College of London Institute of Mental Health, said: “Obviously, losing brain volume is something we’ve always regarded as being a very bad thing. It means you have more neurons that have died and you’ve lost more capacity. The imaging data does seem to suggest people are losing probably slightly more than a teaspoon full of brain.”

Dr Thambisetty, a senior clinical investigator at the US National Institute on Aging, said that study participants receiving the largest dose lost up to three teaspoons of brain volume.

Dr Alex Osborne, policy manager at the Alzheimer’s Society, said: “A drug will not become available in the UK without having strong evidence to show that it is both safe and effective.”

A spokeswoman for Eisai said any volume loss in brains of patients “was not associated with worsening in measured neurodegenerative outcomes”.

A spokeswoman for Eli Lilly said: “Brain volume change with potential Alzheimer’s disease therapies has broadly been observed though admittedly not well understood. Some experts believe it may be an effect seen on MRI resulting from amyloid plaque removal itself or from reducing inflammation in the brain. We are committed to continue to initiate research to manage the risks for this class of agents.”