In clinical medicine, diagnostic criteria are not only useful everyday tools for the practicing physician, but also represent a conceptual concentrate of the understanding of the etiology and pathophysiology of diseases at a given point in time. Although different sets of diagnostic criteria for Alzheimer's disease (AD) have been developed, the most widely used and best validated by clinico-pathological study to date are the NINCDS-ADRDA (National Institute of Neurological and Communicative Disorders and Stroke – Alzheimer's Disease and Related Disorders Association) criteria which were published in 1984 (McKhann et al., 1984). These criteria are largely based on the exclusion of other conditions that may cause dementia and can be succinctly but fairly summarized as defining AD as an “acquired progressive cognitive, behavioral, and functional impairment with no other obvious cause”. Clearly, the NINCDS-ADRDA criteria were etiology- and pathophysiology-agnostic in that they failed to point at any specific etiology, not even a degenerative one. They were also developed before other important causes of dementia, such as dementia with Lewy bodies, fronto-temporal dementia and subcortical vascular dementia had been fully described and characterized. The recent publication of a substantially revised version of these criteria (Sperling et al. 2011; Albert et al., 2011; McKhann et al., 2011), heralded by a largely European initiative four years ago (Dubois et al., 2007) has been greeted with great interest by the field. The newly proposed criteria reflect the substantial insights on disease pathophysiology gained over the last decades, especially regarding the molecular pathology of AD and the time course of such pathology in relation to clinical symptoms and disease.