During the past three decades psychiatric research has made use of the expertise and techniques of many medical disciplines, among them neuroendocrinology, immunology, virology, genetics, and molecular biology. This book provides a concise overview of our present knowledge on the immunological aspects of psychiatric diseases, in particular schizophrenia, drug addiction and Alzheimer’s disease. In addition, fundamental questions concerning the bi-directional interactions between the central nervous system and the immune system are discussed and the role of viruses and infectious processes closely examined. As such, this book offers a unique presentation of the state of the art in psychoimmunology and, at the same time, shows many important challenges for future research into the field of intersystemic interactions and their impact on the etiology and pathogenesis of psychiatric diseases. Psychiatrists and neurologists will gain a better understanding of the biological basis of psychiatric diseases while immunologists, neuroimmunologists, neurobiologists, neuroendocrinologists and virologists will find it a valuable source of new information on psychoimmunology research.