A major Cochrane review has found that drugs designed to target amyloid beta proteins in the brain are unlikely to provide meaningful benefits for patients. At the same time, these treatments appear to increase the risk of brain swelling and bleeding. Amyloid beta is a protein that builds up in the brains of people with Alzheimer's disease, often years before symptoms appear. Scientists have long believed that removing these protein deposits could slow or prevent the disease. Based on this idea, several drugs have been developed to clear amyloid from the brain. Large Review of Alzheimer's Drug Trials The new analysis combined results from 17 clinical trials involving 20,342 participants. All of the studies focused on people with mild cognitive impairment or early-stage Alzheimer's dementia. Researchers have suggested that targeting amyloid early in the disease might offer the best chance of slowing progression.…