Hippocampus and entorhinal cortex in frontotemporal dementia and alzheimer’s disease: a morphometric {MRI} study

Abstract

Background: Magnetic resonance imaging (MRI) of hip-pocampal atrophy is a sensitive but not specific method to support the clinical diagnosis of early Alzheimer’s disease (AD). We recently described our findings that atrophy of the entorhinal cortex (ERC) in frontotemporal dementia (FTD) is equal to that found in AD but that hippocampal atrophy in FTD is less than that found in AD. The MRI volumes of these structures provide a topographic repre-sentation of the region of interest. We hypothesized that two different dementias with distinct histopathologic and clinical features might, in addition to quantitative pat-terns, display topographically different patterns of atrophy. Methods: We adopted a morphometric approach to mon-itor the pattern of atrophy of the hippocampus and the ERC by computing two-dimensional profiles from MRI volumes of the structures in control subjects and patients with FTD and AD. Results: Compared with control subjects, atrophy of the hippocampus in patients with AD was diffuse. In patients with FTD, atrophy of the hippocampus was localized predominantly in the anterior hippocampus, suggesting a different pattern of hippocampal atrophy in FTD com-pared with AD. The amount and pattern of atrophy of the entorhinal cortex was virtually equal in both demented groups. Conclusions: This study provides novel data on the nature of medial temporal lobe atrophy in FTD. Morphometric MRI may be a useful technique for characterizing different patterns of atrophy in primary degenerative dementias in vivo. Biol Psychiatry 2000;47:1056–1063 © 2000 So-ciety of Biological Psychiatry Key Words: Alzheimer’s disease, brain, dementia, ento