RESUMEN
In the present chapter, that is part of a more comprehensive work performed by the Argentine Consortium for Dementia Study - Consortium Argentino para el Estudio de la Demencia (CAED), we describe the most frequent forms of beginning for the four more prevalent types of dementia: Alzheimer's disease, dementia with Lewy bodies, vascular dementia and frontotemporal dementia). Despite this, it must be kept in mind, that frequently the clinical presentation is not typical and the diagnostic impression at the disease's beginning is controversial comparing it with the etiological diagnosis reached when the dementia is definitively installed. This issue must be considered when the initial impression is given to the patient and/or relatives. It must be clarified, in this instance, that this impression is based in statistical data of ways of presentation, but the definitive diagnosis could be different according to the dementia evolution.