Impaired Visual Recognition Memory in Amnestic Mild Cognitive Impairment is Associated with Mesiotemporal Metabolic Changes on Magnetic Resonance Spectroscopic Imaging

Article type: Research Article

Authors: Didic, Mira^{a; *} | Ranjeva, Jean-Philippe^b | Barbeau, Emmanuel^c | Confort-Gouny, Sylviane^b | Le Fur, Yann^b | Felician, Olivier^a | Mancini, Julien^d | Poncet, Michel^a | Ceccaldi, Mathieu^a | Cozzone, Patrick^b

Affiliations: [a] Service de Neurologie et de Neuropsychologie, Pôle de neurosciences cliniques, Assistance Publique des Hôpitaux de Marseille, Hôpitaux de la Timone, CMRR PACA Ouest and INSERM U751, Faculté de Médecine, Université de la Méditerranée, Marseille, France | [b] Centre d'Exploration Métabolique par Résonance Magnétique (UMR CNRS 6612), Université de la Méditerranée, Marseille, France | [c] Université de Toulouse, UPS, Centre de Recherche Cerveau et Cognition and CNRS, CerCo, Toulouse, France | [d] Université Aix-Marseille, Faculté de Médecine, Laboratoire d'Enseignement et de Recherche sur le Traitement de l'Information Médicale (LERTIM, EA 3283), Marseille and Service de Santé Publique et d'Information Médicale (SSPIM), Assistance Publique des Hôpitaux de Marseille, Hôpitaux de la Timone, France

Correspondence: [*] Correspondence to: Dr. Mira Didic, Service de Neurologie et Neuropsychologie, CHU la Timone, 264, rue Saint Pierre, 13385 Marseille Cedex 5, France. Tel.: +33 4 91 38 59 28; Fax: +33 4 91 38 49 22; E-mail: [email protected].

Abstract: In the early stages of Alzheimer's disease (AD), neurofibrillary tangles develop in the mesial temporal lobe (MTL), first in the anterior subhippocampal (perirhinal/entorhinal) cortex and then in the hippocampal formation. This region plays a key role in visual recognition memory (VRM). VRM has been reported to be impaired in patients with amnestic mild cognitive impairment (aMCI). The aim of the present study was to determine if an impairment of VRM is associated with metabolic changes in the MTL using magnetic resonance spectroscopic imaging and if evaluating VRM can contribute to the early diagnosis of AD. 28 patients with aMCI and 28 controls underwent a full neuropsychological assessment including an evaluation of VRM using the DMS48. NAA/mIno ratios, reduced in patients with AD and associated with the severity of pathological changes, were determined in the MTL. aMCI-patients were further divided into two subgroups according to their VRM performance. aMCI-patients showed decreased NAA/mIno levels in the right hippocampus compared with controls. aMCI-patients with impaired VRM showed decreased NAA/mIno ratios in the MTL bilaterally, including a region that sampled the left anterior subhippocampal cortex, compared to controls. No changes were found in aMCI patients with normal VRM. Performance on the DMS48 correlated with NAA/mIno levels in the anterior MTL. Clinical 6-year follow-up data (available for 78.6% of the aMCI-patients) indicates that impaired performance on the DMS48 could predict conversion to AD with a sensitivity and specificity of 81.8%. These findings provide further evidence that impaired VRM, as a hallmark of MTL dysfunction, may contribute to the early diagnosis of AD.

Keywords: Alzheimer's disease, entorhinal cortex, magnetic resonance spectroscopy, mesial temporal lobe, mild cognitive impairment, MRSI, perirhinal cortex, visual recognition memory, DMS48

DOI: 10.3233/JAD-2010-101257

Journal: Journal of Alzheimer's Disease, vol. 22, no. 4, pp. 1269-1279, 2010