Cochrane review finds Alzheimer’s drugs offer little benefit, raise brain bleeding risk

Anti-amyloid Alzheimer’s drugs cleared plaque, but they did not deliver a meaningful slowdown in memory loss or daily decline for patients with early disease, and they raised the risk of brain swelling and bleeding.

A Cochrane review published on April 16, 2026, examined 17 clinical trials involving 20,342 people with mild cognitive impairment or mild dementia due to Alzheimer’s disease. Its conclusion was blunt: the drugs likely have no clinically meaningful positive effect, and the changes seen in cognition and dementia severity after 18 months were absent or trivial, far below thresholds experts use to define a minimum important difference.

Francesco Nonino, the review’s lead author and a neurologist and epidemiologist at the IRCCS Institute of Neurological Sciences of Bologna in Italy, said the evidence showed no meaningful difference for patients. He warned that statistical significance should not be confused with clinical relevance. The review also found that the medicines do remove amyloid proteins from the brain, but that plaque clearance did not translate into a benefit people or families would be likely to notice in everyday life.

The analysis included the newer drugs lecanemab, sold as Leqembi, and donanemab, sold as Kisunla, as well as older agents that were later discontinued after failed trials, including aducanumab, bapineuzumab, crenezumab, gantenerumab, ponezumab, remternetug and solanezumab. That broad grouping is already driving a sharp backlash. Alzheimer’s Research UK said the review had major limitations and argued that it painted an entire class of drugs with the same brush.

Susan Kohlhaas, the charity’s executive director of research and partnerships, said different anti-amyloid treatments can work in different ways. John Hardy, professor at the UCL Institute of Neurology, said lecanemab and donanemab had shown that slowing Alzheimer’s is possible and had opened the door to a new era of treatment. The charity also argued that there is no agreed definition of what counts as clinically meaningful, and that even a delay of several months could matter to families facing a progressive and ultimately fatal disease.

The dispute lands in the middle of a cost and access fight over the first disease-modifying Alzheimer’s drugs. In the United Kingdom, NICE has said the benefits of lecanemab and donanemab are too small to justify their cost for NHS use in England and Wales. In the United States, the FDA granted traditional approval to lecanemab on July 6, 2023, and approved donanemab on July 2, 2024.

The new review strengthens the argument from skeptics that amyloid removal alone is not enough. For drugmakers, insurers and public health systems, the question is no longer whether the science can clear plaques, but whether that result is large enough, safe enough and cheap enough to matter in real life.