title: Association between executive dysfunction and hippocampal volume in Alzheimer's disease.
abstract: BACKGROUND
  Some previous research has hypothesized that executive dysfunction in patients with early Alzheimer's disease (AD) occurs as a result of a disconnection between different cerebral areas. The aim of the present study was to evaluate how the hippocampal volume influences executive function as a non-memory cognitive function.
  
  
  METHODS
  From 157 consecutive patients with AD or amnestic mild cognitive impairment (A-MCI), we recruited 107 subjects who had a global Clinical Dementia Rating (CDR) of 0.5 or 1.0 and whose degree of hippocampal atrophy had been measured using magnetic resonance imaging (MRI); the severity of atrophy was assessed using the voxel-based specific regional analysis for Alzheimer's disease (VSRAD) system. We divided the subjects into three groups: mild atrophy, 0 < Z-score < 1.0 (N = 21); moderate atrophy, 1.0 ≤ Z-score < 2.0 (N = 46); or severe atrophy, 2.0 ≤ Z-score < 4.0 (N = 40) according to the Z-score and compared the Frontal Assessment Battery (FAB) and its subtest scores between each atrophy group.
  
  
  RESULTS
  The results demonstrated that age, sex ratio, duration of illness, education years, MMSE score, Behave-AD score, and proportion of atrophy area in total brain (%) were not significantly different among the three groups. Only the go/no-go score among the six subtests was significantly lower for increasing atrophy severity (P < 0.05). Furthermore, hippocampal atrophy significantly influenced the go/no-go score independently of interactions from whether the diagnosis was early AD or A-MCI (P < 0.05).
  
  
  CONCLUSIONS
  These results support a significant association between hippocampal atrophy and executive dysfunction as a non-memory cognitive impairment in patients with early AD and A-MCI.
authors.affiliation: Department of Psychiatry, Jikei University School of Medicine, Kashiwa Hospital, Chiba, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nagata
authors.forename: Shunichiro
authors.initials: S
authors.lastname: Shinagawa
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ochiai
authors.forename: Ryo
authors.initials: R
authors.lastname: Aoki
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kasahara
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Nukariya
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakayama
mesh_terms: D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology / Q000209:etiology; D001284:Atrophy / Q000473:pathology; D060825:Cognitive Dysfunction / Q000150:complications / Q000473:pathology / Q000523:psychology; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007564:Japan; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D016743:Mental Competency; D011939:Mental Recall / Q000502:physiology; D009483:Neuropsychological Tests; D009929:Organ Size; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D012720:Severity of Illness Index