Functional MR imaging using a visually guided saccade paradigm for comparing activation patterns in patients with probable Alzheimer’s disease and in cognitively able elderly volunteers

BACKGROUND AND PURPOSE: Alzheimer’s disease is associated with progressive visuo-spatial dysfunction. This study used functional MR (fMR) imaging with an eye movement paradigm to investigate differences in visuospatial cognition between patients with probable Alzheimer’s disease (pAD) and cognitively able elderly volunteers. METHODS: Using established, although imperfect, clinical criteria, patients with pAD (n 5 18) and cognitively able elderly volunteers (n 5 10) were selected for study. All patients un-derwent echo-planar fMR imaging at 1.5 T. The visually guided saccade paradigm consisted of alternating periods (30 s) of central fixation and visually guided saccades to a target ap-pearing randomly along the horizontal meridian. Activation maps were derived using a voxel-wise t test, comparing the signal intensities between the two steady-state conditions. The acti-vation patterns were characterized by Talairach coordinates, activation volumes, and laterality ratios (LRs). RESULTS: Statistically significant differences existed between the activation patterns of the patients with pAD and those of the volunteers. In contrast to the control group, a left-dominant parietal activation pattern and enhanced prefrontal cortical activation were observed in mos