This volume contains the proceedings of a symposium held in Marseille on April 6, 1992, on the topic "Heterogeneity of Alzheimer's disease. " This was the eighth of a continuing and very successful series of meetings related to Alzheimer's disease organized by the Fondation Ipsen pour la Recherche Therapeutique. These symposia, known as "Colloques medecine et recherche," started in 1987 and have dealt with widely different aspects of the disease such as immunology, genetics, neuronal grafting, biological markers, imaging, growth factors, and last year's less conventional topic of Neurophilo- sophy and Alzheimer's disease. The next IPSEN symposium dedicatet to Alz- heimer's disease will take place in Lyon on June 21, 1993, and will deal with "Amyloid protein precursors in development, aging, and alzheimer's disease. " It is being organized by Konrad Beyreuther, Colin Masters, Marc Trillet, and Yves Christen. Until a few years ago, several names were used to refer to the most common cause of dementia in the elderly. They included such terms as "senile psycho- sis," "organic brain syndrome," and "senile dementia. " Following Kraepelin, the term "Alzheimer's disease" was often restricted to an uncommon condition starting at a younger age (before 60 or 65 years of age).