Key Alzheimer's Question Answered (VIDEO) Washington University School of Medicine This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption Neurologists finally have an answer to one of the most important questions about Alzheimer's disease: In a study published in Science Express, researchers show that rising brain levels of a plaque-forming substance occur not because the brain makes more of the substance but because it can no longer clear the substance as well. The results are likely to aid efforts to improve diagnosis and treatment. Credit Clark Bowen, Washington University in St. Louis Usage Restrictions Embargoed until Dec. 9 at 2 p.m. ET License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.