[The diagnostic approach to early Alzheimer's disease. What are we talking about? Conceptual considerations].

Progress in knowledge of the physiopathology of Alzheimer's disease over the last few decades has allowed much earlier diagnosis, even before the onset of clinical symptoms. Although the use of biomarkers is still far from being widespread and cannot be recommended outside research settings, their potential use has led to a review of the diagnostic criteria employed in the last few years. Among other criteria, asymptomatic and prodromal phases have been definitively incorporated into the spectrum of the disease and have been redefined. In future, the possibility of an earlier and more accurate diagnosis will allow the application of treatments acting in these phases, delaying progression to more advanced stages or even halting the disease before clinical manifestations develop. Currently, such treatments are still far from being a reality and interest in biomarkers centers on research since their detection could allow standardization of the samples used in clinical trials and exclusion of individuals showing signs of prodromal disease but who will never develop the disease.