MEMORY IMPAIRMENTS ASSOCIATED WITH HIPPOCAMPAL VERSUS PARAHIPPOCAMPAL-GYRUS ATROPHY - AN MR VOLUMETRY STUDY IN ALZHEIMERS-DISEASE

Delayed memory impairments and medial temporal-lobe atrophy are consid ered to be cardinal features of Alzheimer's disease (AD). The goal of the present magnetic resonance (MR) volumetry study was to investigate the relationship between both features. We determined MR-derived esti mates of hippocampal and parahippocampal volume in a sample of 27 AD p atients and in a group of 26 healthy control subjects (NCs) of compara ble age and education. We examined the performance of the two groups o n immediate and delayed recall trials of an auditory-verbal list-learn ing task (CVLT), a visual non-verbal memory task (Visual Reproduction of the WMS-R), and a screening procedure that provides an estimate of overall cognitive functioning (DRS). Volumes of the hippocampus and th e parahippocampal gyrus were significantly smaller in AD patients than in NCs. AD patients were impaired in their overall level of cognitive functioning and showed memory deficits under immediate and delayed re call conditions. The association between medial temporal-lobe atrophy and cognitive impairments in AD was found to be highly specific: Hippo campal volume correlated positively with delayed but not immediate rec all of the verbal-auditory list learning task. In contrast: parahippoc ampal gyrus volume, specifically in the right hemisphere, was positive ly related to delayed but not immediate recall of the non-verbal visua l memory task. In NCs: there was a trend towards a negative associatio n between hippocampal volumes and delayed verbal recall. Our results s uggest that hippocampal and parahippocampal gyrus atrophy in AD are re lated to distinct aspects of the patients' memory impairments. Our fin dings have implications for current discussions regarding contribution s of the hippocampus and the parahippocampal gyrus to memory in the in tact human brain. (C) 1998 Elsevier Science Ltd. All rights reserved.