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Structure and function of medial temporal and posteromedial cortices in early Alzheimer’s disease
Author(s) -
Miettinen Pekka S.,
Pihlajamäki Maija,
Jauhiainen Anne M.,
Niskanen Eini,
Hänninen Tuomo,
Vanninen Ritva,
Soininen Hilkka
Publication year - 2011
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2011.07745.x
Subject(s) - entorhinal cortex , posterior cingulate , temporal lobe , atrophy , retrosplenial cortex , neuroscience , hippocampal formation , hippocampus , psychology , alzheimer's disease , voxel based morphometry , magnetic resonance imaging , pathology , cardiology , medicine , cortex (anatomy) , disease , white matter , epilepsy , radiology
Medial temporal lobe (MTL) atrophy and posteromedial cortical hypometabolism are consistent imaging findings in Alzheimer’s disease (AD). As the MTL memory structures are affected early in the course of AD by neurofibrillary tangle pathology, the posteromedial metabolic abnormalities have been postulated to represent remote effects of MTL alterations. In this study, we investigated with functional MRI (fMRI) the structure–function relationship between the MTL and posteromedial regions, including the retrosplenial, posterior cingulate and precuneal cortices, in 21 older controls (OCs), 18 subjects with amnestic mild cognitive impairment (MCI) and 16 AD patients during a word list learning task. In the voxel‐based morphometric and volumetric analyses, the MCI subjects showed smaller entorhinal volume than OCs ( P = 0.0001), whereas there was no difference in the hippocampal or posteromedial volume. AD patients, as compared with MCI patients, showed pronounced loss of volume in the entorhinal ( P = 0.0001), hippocampal ( P = 0.01) and posteromedial ( P = 0.001) regions. The normal pattern of posteromedial fMRI task‐induced deactivation during active encoding of words was observed bilaterally in the OCs, but only in restricted unilateral left posteromedial areas in the MCI and AD patients. Across all subjects, more extensive impairment of the retrosplenial and posterior cingulate function was significantly related to smaller entorhinal ( P = 0.001) and hippocampal ( P = 0.0002) volume. These findings demonstrate that entorhinal atrophy and posteromedial cortical dysfunction are early characteristics of prodromal AD, and precede and/or overwhelm atrophy of the hippocampus and posteromedial cortices. Disturbances in posteromedial cortical function are associated with morphological changes in the MTL across the continuum from normal aging to clinical AD.