Mild cognitive impairment:: a risk indicator of later dementia, or a preclinical phase of the disease?

Objectives The proposals for classifying the transitional range between normal, ageing-associated cognitive dysfunctions and those suggestive of evolution towards dementia do not clarify whether the profiles are risk indicators of later cognitive impairment or represent preclinical phases of dementia. Methods Retrospective study of the baseline neuropsychological performance of ten subjects with subjective complaints of memory loss which evolved to dementia within 2 years and who meet clinical and neurological diagnosis for Probable Alzheimer's Disease (Progression group). They were compared with 34 normal subjects (Normative group), 33 patients with subjective complaints of memory who in 2 year did not evolve towards dementia and presented a stable profile (Stable group), and 47 Alzheimer's patients (Alzheimer group). A broad neuropsychological battery was administered to assess a range of cognitive functions. Results The Progression group presented a globally poor baseline neuropsychological performance, except in Working Memory, with clear deficits in Episodic Memory and Visual Memory. In the logistic regression analysis, Delayed Verbal Memory was significant as prognostic value for 80-5% of cases. Conclusion Deficit on Episodic and Visual Memory at least 1.5 SD below T = 50 are preclinical manifestations of dementia in subjects with complain of memory loss. The use of broad neuropsychological batteries and the quantitative assessment of deficits is essential to identify and predict the risk of dementia. Copyright (C) 2007 John Wiley & Sons, Ltd.