A review of anti-amyloid drugs, once hailed as a breakthrough in Alzheimer’s treatment, suggested they had no clinically meaningful effect.

Plaques of malformed amyloid proteins form in Alzheimer’s patients’ brains, and new drugs such as aducanumab and lecanemab have targeted those proteins on the assumption that they cause the disease.

The Cochrane review found that while the drugs’ effect was statistically detectable, it would likely not be noticed by patients. The treatments have been controversial: Aducanumab’s approval by US regulators was called a “disgraceful decision” by one pharma watcher.

But some researchers told the Science Media Center that the Cochrane review conflated failed drugs such as aducanumab with newer ones, thus hiding the effect of the more modern treatments.