title: Early-onset and late-onset Alzheimer's disease are associated with distinct patterns of memory impairment.
abstract: The goal of this study was to investigate the specific patterns of memory breakdown in patients suffering from early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD). Twenty EOAD patients, twenty LOAD patients, twenty matched younger controls, and twenty matched older controls participated in this study. All participants underwent a detailed neuropsychological assessment, an MRI scan, an FDG-PET scan, and AD patients had biomarkers as supporting evidence of both amyloïdopathy and neuronal injury. Results of the neuropsychological assessment showed that both EOAD and LOAD groups were impaired in the domains of memory, executive functions, language, praxis, and visuoconstructional abilities, when compared to their respective control groups. EOAD and LOAD groups, however, showed distinct patterns of memory impairment. Even though both groups were similarly affected on measures of episodic, short term and working memory, in contrast semantic memory was significantly more impaired in LOAD than in EOAD patients. The EOAD group was not more affected than the LOAD group in any memory domain. EOAD patients, however, showed significantly poorer performance in other cognitive domains including executive functions and visuoconstructional abilities. A more detailed analysis of the pattern of semantic memory performance among patient groups revealed that the LOAD was more profoundly impaired, in tasks of both spontaneous recall and semantic recognition. Voxel-Based Morphometry (VBM) analyses showed that impaired semantic performance in patients was associated with reduced gray matter volume in the anterior temporal lobe (ATL) region, while PET-FDG analyses revealed that poorer semantic performance was associated with greater hypometabolism in the left temporoparietal region, both areas reflecting key regions of the semantic network. Results of this study indicate that EOAD and LOAD patients present with distinct patterns of memory impairment, and that a genuine semantic impairment may represent one of the clinical hallmarks of LOAD.
authors.affiliation: Département de psychologie, Université de Montréal, Montréal, Quebec, Canada; Centre de recherche Institut universitaire de gériatrie de Montréal (CRIUGM), Montréal, Quebec, Canada. Electronic address: sven.joubert@umontreal.ca.
authors.forename: Sven
authors.initials: S
authors.lastname: Joubert
authors.affiliation: Université Aix-Marseille, INSERM, Institut des Neurosciences des Systèmes (INS) UMR 1106, Marseille, France; APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France; Aix-Marseille Université, CNRS, CRMBM UMR 7339, Marseille, France.
authors.forename: Natalina
authors.initials: N
authors.lastname: Gour
authors.affiliation: APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'Imagerie, ​CEMEREM, Marseille, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Guedj
authors.affiliation: Université Aix-Marseille, INSERM, Institut des Neurosciences des Systèmes (INS) UMR 1106, Marseille, France; APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France.
authors.forename: Mira
authors.initials: M
authors.lastname: Didic
authors.affiliation: APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Guériot
authors.affiliation: APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France.
authors.forename: Lejla
authors.initials: L
authors.lastname: Koric
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339, Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'Imagerie, ​CEMEREM, Marseille, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Ranjeva
authors.affiliation: Université Aix-Marseille, INSERM, Institut des Neurosciences des Systèmes (INS) UMR 1106, Marseille, France; APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Felician
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339, Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'Imagerie, ​CEMEREM, Marseille, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Guye
authors.affiliation: Université Aix-Marseille, INSERM, Institut des Neurosciences des Systèmes (INS) UMR 1106, Marseille, France; APHM, Hôpitaux de la Timone, Service de Neurologie et de Neuropsychologie, Marseille, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Ceccaldi
mesh_terms: D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000473:pathology / Q000523:psychology*; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D008569:Memory Disorders / Q000000981:diagnostic imaging / Q000473:pathology / Q000523:psychology*; D008875:Middle Aged; D009483:Neuropsychological Tests
keywords: Cognition; Early-onset Alzheimer's disease; Late-onset Alzheimer's disease; Memory; Neuropsychological tests; Semantic memory