Hemispheric differences in hippocampal volume predict verbal and spatial memory performance in patients with Alzheimer's disease

Atrophy of the hippocampal formation, a region important for the acquisitio n of new declarative knowledge, has been well-documented in Alzheimer's dis ease (AD), although the relation of such atrophy to the extent of memory dy sfunction in these patients has been less clear. In the present study, 18 p atients with a clinical diagnosis of probable AD were studied with a high-r esolution, quantitative magnetic resonance imaging (MRI) protocol, as well as the verbal and spatial versions of the Buschke controlled learning task. The volumes of the hippocampal formation and, as a controlled for generali zed atrophy, parahippocampal gyrus and temporal neocortex were computed fro m gapless coronal slices taken perpendicular to the long axis of the hippoc ampus. To correct for individual differences in brain size, volumes of regi ons of interest were divided by total intracranial volume. Separate stepwis e regression analyses (with age, right and left hippocampal, parahippocampa l gyrus, and temporal lobe volumes as the independent variables) showed tha t left hippocampal volume was the best predictor of free retail and delayed free recall of verbal information (P = 0.0042 and P < 0.0001, respectively ). Recall and delayed recall of the spatial location of verbal items were b est predicted by right hippocampal volume (P = 0.0054 and P = 0.0118, respe ctively). Memory scores did not correlate either with parahippocampal gyrus or temporal lobe volume. Furthermore, the relation between hippocampal vol ume and memory function observed in cases with AD did not hold for healthy aged control subjects. (C) 2000 Wiley-Liss, Inc.