The dementias are presented to health practitioners to provide some basic information on the epidemiology and biological bases of the dementias. The diagnostic and clinical problems that the physician or institution faces when caring for demented patients are discussed in depth. In this book some fundamental questions on dementia are addressed, such as: Is the loss of cerebral tissue sufficient to cause dementia? Are neurotransmitter changes necessary and sufficient to produce dementia? Are there thresholds or is there a continuous progression toward the irreversible development of dementia? Are there common pathways in the dementing process? Are there common risk factors? The comparative analysis allows the common and distinctive patterns of the various dementias to be defined, which will ultimately lead to more focused therapeutic interventions. The book is based on the personal experience of the authors who are all directly involved in dementia research or clinical care of the patient. In particular, the main forms of dementia (Alzheimers disease, vascular dementia, Lewy body disease, frontotemporal dementia) are treated as separate chapters by experts in the field. Some chapters are devoted to the care of the patient, which means interventions that provide care for patients at home or in an institution. The economical burden of the illness for the family and the healthcare system and the ethical aspects are also addressed.