title: The Differentiation of Amnestic Type MCI from the Non-Amnestic Types by Structural MRI.
abstract: BACKGROUND
  While amnestic mild cognitive impairment (aMCI) and non-amnestic mild cognitive impairment (naMCI) are theoretically different entities, only a few investigations studied the structural brain differences between these subtypes of mild cognitive impairment. The aim of the study was to find the structural differences between aMCI and naMCI, and to replicate previous findings on the differentiation between aMCI and healthy controls.
  
  
  METHODS
  Altogether 62 aMCI, naMCI, and healthy control subjects were included into the study based on the Petersen criteria. All patients underwent a routine brain MR examination, and a detailed neuropsychological examination.
  
  
  RESULTS
  The sizes of the hippocampus, the entorhinal cortex and the amygdala were decreased in aMCI relative to naMCI and to controls. Furthermore the cortical thickness of the entorhinal cortex, the fusiform gyrus, the precuneus and the isthmus of the cingulate gyrus were significantly decreased in aMCI relative to naMCI and healthy controls. The largest differences relative to controls were detected for the volume of the hippocampus (18% decrease vs. controls) and the cortical thickness (20% decrease vs. controls) of the entorhinal cortex: 1.6 and 1.4 in terms of Cohen's d. Only the volume of the precuneus were decreased in the naMCI group (5% decrease) compared to the control subjects: 0.9 in terms of Cohen's d. Significant between group differences were also found in the neuropsychological test results: a decreased anterograde, retrograde memory, and category fluency performance was detected in the aMCI group relative to controls and naMCI subjects. Subjects with naMCI showed decreased letter fluency relative to controls, while both MCI groups showed decreased executive functioning relative to controls as measured by the Trail Making test part B. Memory performance in the aMCI group and in the entire sample correlated with the thickness of the entorhinal cortex and with the volume of the amygdala.
  
  
  CONCLUSIONS
  The amnestic mild cognitive impairment/non-amnestic mild cognitive impairment separation is not only theoretical but backed by structural imaging methods and neuropsychological tests. A better knowledge of the MCI subtypes can help to predict the direction of progression and create targeted prevention.
authors.affiliation: Department of Psychiatry and Psychotherapy, Semmelweis University Budapest, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Csukly
authors.affiliation: Department of Psychiatry and Psychotherapy, Semmelweis University Budapest, Hungary.
authors.forename: Enikő
authors.initials: E
authors.lastname: Sirály
authors.affiliation: Department of Psychiatry and Psychotherapy, Semmelweis University Budapest, Hungary.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Fodor
authors.affiliation: Department of Neurology, National Institute of Clinical Neurosciences Budapest, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Horváth
authors.affiliation: Department of Psychiatry and Psychotherapy, Semmelweis UniversityBudapest, Hungary; Department of Neurology, Hospital at Péterfy Sándor StreetBudapest, Hungary.
authors.forename: Pál
authors.initials: P
authors.lastname: Salacz
authors.affiliation: Department of Psychiatry and Psychotherapy, Semmelweis University Budapest, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Hidasi
authors.affiliation: Department of Psychiatry and Psychotherapy, Semmelweis University Budapest, Hungary.
authors.forename: Éva
authors.initials: É
authors.lastname: Csibri
authors.affiliation: Magnetic Resonance Imaging Research Center, Semmelweis University Budapest, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Rudas
authors.affiliation: Magnetic Resonance Imaging Research Center, Semmelweis University Budapest, Hungary.
authors.forename: Ádám
authors.initials: Á
authors.lastname: Szabó
keywords: MRI; amnestic; mild cognitive impairment; neuropsychological test; non-amnestic