Exploring visuospatial short-term memory defect in Alzheimer's disease.

The present study aimed at controlling two variables that may affect the visuospatial short-term memory of Alzheimer patients: visuospatial coding efficiency and response modality. Thirty patients affected by Alzheimer-type dementia with relatively spared visuo-perceptual functions were tested under three conditions, all of which employed the same kind of stimuli (visuospatial patterns). At all memory tasks, patients achieved scores significantly lower than those of 30 age- and education-matched normal subjects. Patients did not benefit from longer presentation time, nor did their performance improve with pointing response modality, although they performed perceptual pattern recognition as well as did controls. These data confirm that visuospatial immediate memory capacity is reduced in dementia.