A major review of anti-amyloid drugs for Alzheimer's disease has concluded that their effects on cognitive decline are 'trivial', dealing a blow to hopes that the treatments represent a breakthrough. The Cochrane review, which analysed data from 17 clinical trials involving over 20,000 patients, found no clinically meaningful improvement in cognition or dementia severity over 18 months.
The drugs, including lecanemab and donanemab, work by clearing amyloid plaques from the brain, a hallmark of Alzheimer's. While some trials showed small statistical benefits, the review's authors argue these are too minor for patients or caregivers to notice. They also highlighted risks of brain swelling and bleeding, and the burden of regular intravenous infusions and MRI scans.
The findings have reignited debate over the drugs' value. In the UK, the National Institute for Health and Care Excellence (Nice) initially ruled the drugs were not cost-effective for the NHS, despite slowing disease progression by four to six months. Nice is now reconsidering after an appeal from manufacturers.
Critics of the review, including Alzheimer's Research UK, argue it unfairly lumps together older, failed drugs with newer, more effective ones. Only two of the 17 trials involved lecanemab and donanemab, which are approved in the UK. Professor Charles Marshall of Queen Mary University said pooling results from effective and ineffective treatments inevitably dilutes the average effect.
Professor Robert Howard of UCL expressed concern about raising false hopes, stating that even the best-performing drugs do not produce clinically meaningful changes. The review's authors call for exploring new treatment approaches beyond amyloid removal.
