 1.Men or Women 50 years old or more. 2. Patients with mild cognitive impairment MCI with progressive hippocampal amnestic syndrome, isolated or associated to other cognitive disorders defined by the Free and cued selective reminding test FCSRT with Free Recall or 17 OR Total Recall 40 , according to the Grober and Buschke procedure, modified according to the results of PREAL study 3.Clinical Dementia Rating CDR 0.5 4. General cognition and functional performance sufficiently preserved such that a diagnosis of Possible or Probable Alzheimers Disease based on Diagnostic and Statistical Manual of Mental Disorders DSM-IV criteria cannot be made by the site physician at the time of the screening visit. This evidence must be fully documented in the subjects study file before the Randomization visit. 