"An experimental drug dramatically reduced the toxic plaques found in the brains of patients with Alzheimers disease a team reports httpnature.comarticlesdoi.nature in the journal Nature. Results from a small number of patients who received a high dose of the drug called aducanumab https_usresearchpipelinebiogenpipeline.html hint that it may also be able to slow the loss of memory and thinking. If that hint of a clinical benefit is confirmed it would be a game changer in the fight against Alzheimers disease says Dr. Eric Reiman httpbanneralz.orgaboutusourleadership.aspx executive director of the Banner Alzheimers Institute in Phoenix. Reiman wrote a commentary that accompanies the study in Nature. But it will take much larger studies to show for sure whether aducanumab really does slow down Alzheimers disease Reiman says. Officials of Biogen https_usresearchpipelinebiogenpipeline.html which is developing the drug were also cautious about interpreting the results of the study which included  patients in the early stages of Alzheimers disease. We think we have something important here says Dr. Alfred Sandrock https_usaboutbiogenleadershipleadershipdetail.sandrock_alfred.html chief medical officer for Biogen. We hope were right because if its true it would benefit millions of patients. But we dont know were right yet.  The results are encouraging for pharmaceutical companies that have spent billions of dollars on efforts to come up with the first drug to treat the underlying cause of Alzheimers. Those efforts have failed to produce a single approved drug http so far. But last summer Biogen began presenting its results with aducanumab at scientific meetings including the Alzheimers Association https International Conference in July. These early reports suggested the drug had a remarkable ability to remove plaques in the brain. Sign Up For The Health Newsletter See how medical research insurance coverage and other news affect your health sent weekly. Top of Form Email address Bottom of Form By subscribing you agree to NPRs terms of use https and privacy policy https It was surprising encouraging and thoughtprovoking to see such a striking reduction of existing plaques Reiman says. The publication httpdx.doi.org.nature in Nature on Wednesday provides details about those early reports. Biogen has already begun two much larger studies of aducanumab. They will include a total of  patients and results are still several years off. But there are reasons to think aducanumab may succeed where other drugs have failed. One is that the drug appears to ignore benign forms of amyloid protein while attacking the toxic forms thought to damage brain cells. Another is that aducanumab seems to enhance the ability of existing immune cells in the brain to devour toxins including amyloid. But theres a downside. The process of removing plaque sometimes causes fluid to build up in the brain. In rare cases it can also cause bleeding. These side effects are known as amyloidrelated imaging abnormalities or ARIA. We were actually anticipating that we would see it Sandrock says. And the researchers did. Twenty patients dropped out of the trial because of adverse effects. If aducanumab works in larger studies it could help settle a longrunning debate about whether amyloid is really the root cause of Alzheimers. This idea is known as the amyloid hypothesis https_betaamyloid.pdf. And large studies showing that removing amyloid can preserve memory and thinking would go a long way toward validating the amyloid hypothesis Sandrock says. Results like those could also lead to the first approved drug to treat the underlying cause of Alzheimers rather than just the symptoms."