Neuropsychological markers of dementia in patients with memory complaints

To identify neuropsychological markers able to predict evolution towards dementia, through the detection of differential neuropsychological characteristics in a group of subjects complaining of memory loss, in a longitudinal, two-year follow-up study.

Longitudinal and retrospective comparisons of neuropsychological performance in: (a) subjects complaining of memory loss who, after a two-year period, met neurological and clinical diagnostic criteria for probable AD, and (b) subjects from the same group who did not progress towards dementia. A sample of 43 subjects were administered a comprehensive neuropsychological battery evaluating orientation, logical-verbal and visuoperceptive reasoning, immediate and delayed verbal and visual memory, attention, learning, executive functions and semantic and phonemic verbal fluency.

Of the 43 subjects evaluated and then re-evaluated two years later, ten (23%) progressed to dementia according to the NINCS-ADRDA criteria for probable Alzheimer's disease. The neuropsychological performance of the rest of the subjects (n=33) over the two examinations was stable. In the retrospective analysis the principal differences between the two groups were found in the intensity of the initial memory deficits (WMS-R) and in the impairment of other cognitive areas in the dementia group: formation of concepts, vocabulary and similarities (WAIS), learning (WMS-R) and several executive functions.

The deficits in cognitive areas other than memory are significant in subjects with memory complaints who progress towards dementia within two years. Memory complaints represent a risk factor that is at least as important as actual memory loss. Recent proposals for adding descriptive labels to the diagnosis of Mild Cognitive Impairment (MCI) in order to reflect the neuropsychological functions impaired in addition to memory (Petersen, 2001a), may be decisive from the prognostic viewpoint.