This volume contains the proceedings of a symposium which took place in Toulouse on April 24,1989. The Fondation IPSEN pour la Recherche Therapeutique organized this meeting for the purpose of gathering the most current ideas concerning biological markers of Alzheimer's disease. The papers presented may be roughly subdivided into three groups: The first one deals with the markers of Alzheimer's disease at the level of the brain itself. They are studied either by examining the CSF or by using techniques such as nuclear magnetic resonance. These approaches are aimed at demonstrating cerebral changes as shown by the debris resulting from the disease or, as is the case with nuclear magnetic resonance, by studying the possible neurochemical abnormalities that occur in earlier stages of Alzheimer's disease. The second series of papers deals with possible extraneuronal changes in the blood, in the skin or in other organs of Alzheimer's disease patients. The third group addresses the most current research on the genetic abnormalities which may be found in individuals suffering from Alzheimer's disease. The contributions compiled in this volume provide a unique view on the state of the art of these aspects of Alzheimer's disease and their relation to both pathogenesis and in vivo diagnosis of the disease."