title: Functional connectivity changes differ in early and late-onset Alzheimer's disease.
abstract: At a similar stage, patients with early onset Alzheimer's disease (EOAD) have greater neocortical but less medial temporal lobe dysfunction and atrophy than the late-onset form of the disease (LOAD). Whether the organization of neural networks also differs has never been investigated. This study aims at characterizing basal functional connectivity (FC) patterns of EOAD and LOAD in two groups of 14 patients matched for disease duration and severity, relative to age-matched controls. All subjects underwent an extensive neuropsychological assessment. Magnetic resonance imaging was used to quantify atrophy and resting-state FC focusing on : the default mode network (DMN), found impaired in earlier studies on AD, and the anterior temporal network (ATN) and dorso-lateral prefrontal network (DLPFN), respectively involved in declarative memory and executive functions. Patterns of atrophy and cognitive impairment in EOAD and LOAD were in accordance with previous reports. FC within the DMN was similarly decreased in both EOAD and LOAD relative to controls. However, a double-dissociated pattern of FC changes in ATN and DLPFN was found. EOAD exhibited decreased FC in the DLPFN and increased FC in the ATN relative to controls, while the reverse pattern was found in LOAD. In addition, ATN and DLPFN connectivity correlated respectively with memory and executive performances, suggesting that increased FC is here likely to reflect compensatory mechanisms. Thus, large-scale neural network changes in EOAD and LOAD endorse both common features and differences, probably related to a distinct distribution of pathological changes.
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13385, Marseille, France; Aix-Marseille Université, INSERM, Institut des Neurosciences des Systèmes (INS) UMR 1106, 13385, Marseille, France; APHM, Hôpitaux de la Timone, Service de Neurologie et Neuropsychologie, 13385, Marseille, France; APHM, Hôpitaux de la Timone, CEMEREM, 13385, Marseille, France.
authors.forename: Natalina
authors.initials: N
authors.lastname: Gour
authors.forename: Olivier
authors.initials: O
authors.lastname: Felician
authors.forename: Mira
authors.initials: M
authors.lastname: Didic
authors.forename: Lejla
authors.initials: L
authors.lastname: Koric
authors.forename: Claude
authors.initials: C
authors.lastname: Gueriot
authors.forename: Valérie
authors.initials: V
authors.lastname: Chanoine
authors.forename: Sylviane
authors.initials: S
authors.lastname: Confort-Gouny
authors.forename: Maxime
authors.initials: M
authors.lastname: Guye
authors.forename: Mathieu
authors.initials: M
authors.lastname: Ceccaldi
authors.forename: Jean Philippe
authors.initials: JP
authors.lastname: Ranjeva
mesh_terms: D017668:Age of Onset; D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology*; D001284:Atrophy; D001931:Brain Mapping; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000098:blood supply / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000098:blood supply / Q000473:pathology*; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D013223:Statistics as Topic
chemical_list: D010100:Oxygen
keywords: early onset Alzheimer disease; executive function; late onset Alzheimer disease; magnetic resonance imaging; memory; neural networks