Alzheimer's disease (AD) is increasing rapidly in frequency as the world's population ages and more people enter the major risk period for this age-related disorder. Clinical trials are research studies conducted in people to determine whether treatments are safe and effective. Clinical trials are sometimes referred to as clinical studies; the terms are often used interchangeably, but there are subtle differences between them. Clinical trials test new interventions or drugs to prevent, detect or treat disease. A clinical study is any type of clinical research involving people, regardless of whether it is testing a specific intervention. Clinical studies can also look at other aspects of care, such as improving quality of life. Treatments aimed at reducing symptoms type of trial, new drugs and variations of existing drugs that aim to reduce the symptoms of Alzheimer's disease are tested. Treatments aimed at slowing or stopping the disease type of trial, new drugs designed to slow or stop Alzheimer's are tested. The “amyloid hypothesis” is still regarded by many as a key explanation for AD’s development and progression. According to the amyloid hypothesis, the large Amyloid Precursor Protein (APP) found on brain cell membranes undergoes an abnormal clipping by enzymes (called beta and gamma secretase), resulting in a toxic protein fragment called amyloid-beta.