[Predementia syndromes and mild cognitive impairment: diagnosis and progression to dementia].

Different diagnostic criteria and terms have been proposed to describe clinical predementia syndromes in the elderly, although the epidemiology of these syndromes has not been thoroughly investigated. Particular interest in Mild Cognitive Impairment (MCI) arises from the fact that MCI is thought to be a prodromal phase and therefore highly predictive of subsequent Alzheimer's disease (AD). Several studies have suggested that most of the patients who met the MCI criteria will progress to AD, but rates of conversion to AD and dementia vary widely among studies, partly because of the characteristics of the population studied and the length of follow-up. Furthermore, recent findings suggest that in population-based studies the MCI classification is unstable, in contrast with clinic-based studies where progression is more uniform.