The progression of Alzheimer's may slow once symptoms appear and do significant damage, according to a study investigating an inherited form of the disease. Through an international study, researchers have found rapid neuronal damage begins 10 to 20 years before symptoms appear. The next part of the study involves a clinical trial using a range of imaging techniques, and analysis of blood and cerebrospinal fluid, as participants trial new drugs to test their safety, side effects and changes within the brain.