Affiliations: [a] Department of Basic and Clinical Psychology and Psychobiology, Jaume I University, Castelló de la Plana, Spain
| [b] Center for Brain and Cognition, Pompeu Fabra University, Barcelona, Spain
| [c] Department of Neurology, General Hospital of Valencia, Valencia, Spain
| [d] ERESA Medical Group, Valencia, Spain
Correspondence:
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Correspondence to: Víctor Costumero, Center for Brain and Cognition, Universitat Pompeu Fabra, Ramon Trias Fargas, 25-27, 08005 Barcelona, Spain. Tel.: +34 964 387655; E-mail: [email protected].
Note: [1] These authors contributed equally to this work.
Abstract: Alzheimer’s disease (AD) has been associated with memory impairment due to alterations in the medial temporal lobe (MTL) and the precuneus. Therefore, the goal of this study was to investigate the effects of AD on the brain networks associated with the hippocampus and precuneus during an encoding memory task. 68 mild cognitive impairment patients (MCI), 21 AD patients, and 20 healthy controls (HC) were included. Participants were instructed to memorize landscapes while undergoing fMRI scanning, followed by a recognition test. MCI were followed up clinically for 18 months to track conversion status. Independent component analysis (ICA) was performed to investigate AD effects on precuneus and MTL networks during memory encoding. Behavioral analyses indicate that HC had a better performance than MCI converters (MCIc) and AD. ICA showed that MCIc had significantly higher activation in the MTL-associated network than MCI non converters (MCIn) and AD, including bilateral hippocampus, parahippocampus, and fusiform gyrus. Furthermore, the precuneus-associated network fitted the default mode network, showing a negative correlation with behavioral performance. These findings indicate that the hyperactivation of the hippocampal network displayed by MCIc has potential discrimination capacity to distinguish them of MCIn, and could be interpreted as a compensatory mechanism.
