[Limits and uncertainties about the concept of MCI: contribution of neuropsychological approach].

The diagnosis of Alzheimer disease is earlier with the memory clinics at a stage preceding the DSMIV criterions of dementia when the complaints are only in the field of memory without daylife impairment (stage CDR 0,5 at the Morris clinical dementia rating). This "predemential" stage is obviously more uncertain in terms of diagnosis and prognosis than the later one but some groups declare the same reliability with combining neuropsychology, biological markers in CSF and imagery. The MCI as a pure syndromic definition but the prospective studies have demonstrated that only 20 to 30p. cent of MCI will remain steady after 5 years of following, and several autopsies of MCI have showed that the neuropathological frontier of Alzheimer disease were crossed with neurofibrillary tangles and senile plaques in the hippocampus. Many trials have been conducted in the different fields of neuropsychology, biological markers and imagery to distinguish the MCI "decliners" from the MCI not related to Alzheimer. In that paper we will analyze all the clinical and neuropsychological perspectives to make that distinction with the maximum of reliability. The question of the usefulness of the MCI concept remains open, taking into account the progress in the very early stage diagnosis of Alzheimer's disease.