title: Whole cortical and default mode network mean functional connectivity as potential biomarkers for mild Alzheimer's disease.
abstract: The search for an Alzheimer's disease (AD) biomarker is one of the most relevant contemporary research topics due to the high prevalence and social costs of the disease. Functional connectivity (FC) of the default mode network (DMN) is a plausible candidate for such a biomarker. We evaluated 22 patients with mild AD and 26 age- and gender-matched healthy controls. All subjects underwent resting functional magnetic resonance imaging (fMRI) in a 3.0 T scanner. To identify the DMN, seed-based FC of the posterior cingulate was calculated. We also measured the sensitivity/specificity of the method, and verified a correlation with cognitive performance. We found a significant difference between patients with mild AD and controls in average z-scores: DMN, whole cortical positive (WCP) and absolute values. DMN individual values showed a sensitivity of 77.3% and specificity of 70%. DMN and WCP values were correlated to global cognition and episodic memory performance. We showed that individual measures of DMN connectivity could be considered a promising method to differentiate AD, even at an early phase, from normal aging. Further studies with larger numbers of participants, as well as validation of normal values, are needed for more definitive conclusions.
authors.affiliation: Department of Neurology, University of Campinas (Unicamp), Sao Paulo 13083-970, Brazil. Electronic address: mbalth@unicamp.br.
authors.forename: Marcio Luiz Figueredo
authors.initials: ML
authors.lastname: Balthazar
authors.affiliation: Department of Neurology, University of Campinas (Unicamp), Sao Paulo 13083-970, Brazil.
authors.forename: Brunno Machado
authors.initials: BM
authors.lastname: de Campos
authors.affiliation: Brain Institute of Rio Grande do Sul, Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
authors.forename: Alexandre Rosa
authors.initials: AR
authors.lastname: Franco
authors.affiliation: Department of Neurology, University of Campinas (Unicamp), Sao Paulo 13083-970, Brazil.
authors.forename: Benito Pereira
authors.initials: BP
authors.lastname: Damasceno
authors.affiliation: Department of Neurology, University of Campinas (Unicamp), Sao Paulo 13083-970, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Cendes
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000150:complications / Q000473:pathology*; D015415:Biomarkers / Q000378:metabolism*; D001921:Brain / Q000098:blood supply* / Q000473:pathology; D001931:Brain Mapping; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000209:etiology / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers
keywords: Biomarker; Default mode network; Dementia; Resting state fMRI