Introduction: The Prevalence of Alzheimer's Disease — A Growing Crisis

In 1906, the German physician Alois Alzheimer provided the first description of the “serious and peculiar disease” of mental deterioration that would later on take his name. Alzheimer described the classic pathology of neuritic plaques and neurofibrillary tangles in an affected patient. Since that time, understanding of Alzheimer's disease (AD) has progressed substantially, although the ability to influence disease progression has not progressed as rapidly. It is likely that over the next decade these advances will lead to earlier diagnosis and development of disease-modifying treatments for AD. It is known that two variants of AD exist: a rare hereditary form and a more prevalent sporadic form. As with many neurodegenerative diseases, early clues to the pathology of AD came from the inherited form of the disease. Hereditary links include mutations of the amyloid precursor protein (APP) and the presenilins, both of which are integrally involved in the cascade of events that leads to the deposition of the 42-amino-acid amyloid β protein and the eventual cell death responsible for AD.