title: The language profile of posterior cortical atrophy.
abstract: BACKGROUND
  Posterior cortical atrophy (PCA) is typically considered to be a visual syndrome, primarily characterised by progressive impairment of visuoperceptual and visuospatial skills. However, patients commonly describe early difficulties with word retrieval. This paper details the first systematic analysis of linguistic function in PCA. Characterising and quantifying the aphasia associated with PCA is important for clarifying diagnostic and selection criteria for clinical and research studies.
  
  
  METHODS
  15 patients with PCA, seven patients with logopenic/phonological aphasia (LPA) and 18 age matched healthy participants completed a detailed battery of linguistic tests evaluating auditory input processing, repetition and working memory, lexical and grammatical comprehension, single word retrieval and fluency, and spontaneous speech.
  
  
  RESULTS
  Relative to healthy controls, PCA patients exhibited language impairments across all of the domains examined, but with anomia, reduced phonemic fluency and slowed speech rate the most prominent deficits. PCA performance most closely resembled that of LPA patients on tests of auditory input processing, repetition and digit span, but was relatively stronger on tasks of comprehension and spontaneous speech.
  
  
  CONCLUSIONS
  The study demonstrates that in addition to the well reported degradation of vision, literacy and numeracy, PCA is characterised by progressive oral language dysfunction with prominent word retrieval difficulties. Overlap in the linguistic profiles of PCA and LPA, which are both most commonly caused by Alzheimer's disease, further emphasises the notion of a phenotypic continuum between typical and atypical manifestations of the disease. Clarifying the boundaries between Alzheimer's disease phenotypes has important implications for diagnosis, clinical trial recruitment and investigations into biological factors driving phenotypic heterogeneity in Alzheimer's disease. Rehabilitation strategies to ameliorate the phonological deficit in PCA are required.
authors.affiliation: Dementia Research Centre, Box 16, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK. s.crutch@ucl.ac.uk
authors.forename: Sebastian J
authors.initials: SJ
authors.lastname: Crutch
authors.forename: Manja
authors.initials: M
authors.lastname: Lehmann
authors.forename: Jason D
authors.initials: JD
authors.lastname: Warren
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Rohrer
mesh_terms: D000368:Aged; D001037:Aphasia / Q000209:etiology* / Q000523:psychology*; D001284:Atrophy / Q000473:pathology; D001307:Auditory Perception / Q000502:physiology; D001927:Brain Diseases / Q000473:pathology / Q000523:psychology*; D002540:Cerebral Cortex / Q000473:pathology*; D032882:Comprehension / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000209:etiology* / Q000523:psychology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000473:pathology; D011578:Psycholinguistics; D011597:Psychomotor Performance / Q000502:physiology; D013060:Speech / Q000502:physiology; D013067:Speech Perception / Q000502:physiology