title: Posterior AD-type pathology: cognitive subtypes emerging from a cluster analysis.
abstract: BACKGROUND
  "Posterior shift" of the neuropathological changes of Alzheimer's disease (AD) produces a syndrome (posterior cortical atrophy) (PCA) dominated by high-level visual deficits.
  
  
  OBJECTIVE
  To explore in patients with AD-type pathology whether a data-driven analysis (cluster analysis) based on neuropsychological findings resulted in the emergence of different subgroups of patients; in particular to find out whether it was possible to identify patients with visuospatial deficits consistent with the hypothesis that PCA is a "dorsal stream" syndrome or, rather, whether there were subgroups of patients with different types of impairment within the high-level visual domain.
  
  
  METHODS
  23 PCA and 16 DAT patients were studied. By a principal component analysis performed on a wide range of neuropsychological tasks, 15 variables were obtained that loaded onto five main factors (memory, language, perceptual, visuospatial, and calculation) which entered a hierarchical cluster analysis.
  
  
  RESULTS
  Four clusters of cognitive impairment emerged: visuospatial/perceptual, memory, perceptual/calculation, and language. Only in the first cluster a visuospatial deficit clearly emerged. conclusions: AD pathology produces not only variants dominated by memory (DAT) and, to a lesser extent, visuospatial deficit (PCA), but also other distinct syndromic subtypes with disorders in visual perception and language which reflect a different vulnerability of specific functional networks.
authors.affiliation: Department of Geriatrics, Centre for the Medicine of the Ageing, Neurosciences and Orthopedics, Catholic University, Rome, Italy ; Dementia Center, Italian Hospital Group, Via Tiburtina 188, Guidonia, 00012 Rome, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Cappa
authors.affiliation: Department of Geriatrics, Centre for the Medicine of the Ageing, Neurosciences and Orthopedics, Catholic University, Rome, Italy ; Institute of Clinical Infectious Diseases, Catholic University, 00168 Rome, Italy.
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Ciccarelli
authors.affiliation: Department of Geriatrics, Centre for the Medicine of the Ageing, Neurosciences and Orthopedics, Catholic University, Rome, Italy ; Institute of Clinical Infectious Diseases, Catholic University, 00168 Rome, Italy.
authors.forename: Eleonora
authors.identifier: 0000-0001-8268-671X
authors.initials: E
authors.lastname: Baldonero
authors.affiliation: Department of Psychology, Sapienza University of Rome, 00184 Rome, Italy ; Neuropsychology Unit, IRCCS Fondazione Santa Lucia, 00136 Rome, Italy.
authors.forename: Marialuisa
authors.identifier: 0000-0001-7806-9540
authors.initials: M
authors.lastname: Martelli
authors.affiliation: Department of Geriatrics, Centre for the Medicine of the Ageing, Neurosciences and Orthopedics, Catholic University, Rome, Italy.
authors.forename: Maria Caterina
authors.initials: MC
authors.lastname: Silveri
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000473:pathology* / Q000523:psychology; D001284:Atrophy / Q000473:pathology / Q000523:psychology; D001921:Brain / Q000473:pathology*; D016000:Cluster Analysis; D003071:Cognition; D003072:Cognition Disorders / Q000150:complications / Q000473:pathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests