title: Glucose Metabolic Brain Networks in Early-Onset vs. Late-Onset Alzheimer's Disease.
abstract: OBJECTIVE
  Early-onset Alzheimer's disease (EAD) shows distinct features from late-onset Alzheimer's disease (LAD). To explore the characteristics of EAD, clinical, neuropsychological, and functional imaging studies have been conducted. However, differences between EAD and LAD are not clear, especially in terms of brain connectivity and networks. In this study, we investigated the differences in metabolic connectivity between EAD and LAD by adopting graph theory measures.
  
  
  METHODS
  We analyzed (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) images to investigate the distinct features of metabolic connectivity between EAD and LAD. Using metabolic connectivity and graph theory analysis, metabolic network differences between LAD and EAD were explored.
  
  
  RESULTS
  RESULTS showed the decreased connectivity centered in the cingulate gyri and occipital regions in EAD, whereas decreased connectivity in the occipital and temporal regions as well as increased connectivity in the supplementary motor area were observed in LAD when compared with age-matched control groups. Global efficiency and clustering coefficients were decreased in EAD but not in LAD. EAD showed progressive network deterioration as a function of disease severity and clinical dementia rating (CDR) scores, mainly in terms of connectivity between the cingulate gyri and occipital regions. Global efficiency and clustering coefficients were also decreased along with disease severity.
  
  
  CONCLUSIONS
  These results indicate that EAD and LAD have distinguished features in terms of metabolic connectivity, with EAD demonstrating more extensive and progressive deterioration.
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea; KAIST Institute for Health Science and Technology, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea.
authors.forename: Jinyong
authors.initials: J
authors.lastname: Chung
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea; KAIST Institute for Health Science and Technology, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea.
authors.forename: Kwangsun
authors.initials: K
authors.lastname: Yoo
authors.affiliation: Department of Neurology, School of Medicine and Medical Research Institute, Pusan National University Busan, South Korea.
authors.forename: Eunjoo
authors.initials: E
authors.lastname: Kim
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of MedicineSeoul, South Korea; Neuroscience Center, Samsung Medical CenterSeoul, South Korea.
authors.forename: Duk L
authors.initials: DL
authors.lastname: Na
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea; KAIST Institute for Health Science and Technology, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea.
authors.forename: Yong
authors.initials: Y
authors.lastname: Jeong
keywords: Alzheimer disease; FDG-PET; early-onset; metabolic connectivity; network