Two major drug companies, Eli Lilly and Eisai, are defending their Alzheimer’s disease treatments after a new review suggested they may not work as well as previously thought. The review, done by a respected medical research group called Cochrane, found that these drugs—called anti-amyloid treatments—had little to no real-world benefit in slowing down memory loss or dementia. The researchers said the improvements were so small that they would not make a meaningful difference in patients’ daily lives. The review also raised concerns that these drugs may increase the risk of swelling or bleeding in the brain, a condition called ARIA. This side effect was usually found on brain scans without causing noticeable symptoms in most patients, but long-term effects are still unclear because symptoms were not consistently reported in the studies. The review looked at 17 clinical trials involving over 20,000 patients with early-stage Alzheimer’s disease. While these drugs were expected to work better in the early stages of the disease, the authors concluded that future research focusing on removing amyloid beta (a protein linked to Alzheimer’s) is unlikely to show clear benefits for patients. The review included data from two approved drugs: Kisunla (donanemab) from Eli Lilly and Leqembi (lecanemab) from Biogen and Eisai. Both companies strongly disagreed with the findings. Eli Lilly said their drug, Kisunla, was approved in the UK in October 2024 after a thorough review by independent experts. They pointed to a major trial that showed the drug slowed down cognitive and functional decline in people with early Alzheimer’s over 18 months. The company said they remain confident in the drug’s effectiveness and value for patients. They also criticized the review, saying it grouped together data from unsuccessful drugs that were never approved, which they believe weakens the conclusions about approved treatments. Similarly, Eisai called the review’s methods scientifically questionable because it combined ineffective treatments with their approved drug, Leqembi. They stated that long-term data from over four years of clinical trials and real-world use involving more than 10,000 patients worldwide show that Leqembi continues to benefit patients. The drug has been approved by over 50 regulatory authorities globally.