title: Memory and emotion processing performance contributes to the diagnosis of non-semantic primary progressive aphasia syndromes.
abstract: BACKGROUND
  The two non-semantic variants of primary progressive aphasia (PPA), nonfluent/agrammatic PPA (nfv-PPA) and logopenic variant PPA (lv-PPA), share language features despite their different underlying pathology, and may be difficult to distinguish for non-language experts.
  
  
  OBJECTIVE
  To improve diagnostic accuracy of nfv-PPA and lv-PPA using tasks measuring non-language cognition and emotion processing.
  
  
  METHODS
  Thirty-eight dementia patients meeting diagnostic criteria for PPA (nfv-PPA 20, lv-PPA 18) and 21 matched healthy Controls underwent a comprehensive assessment of cognition and emotion processing, as well as a high-resolution structural MRI and a PiB-PET scan, a putative biomarker of Alzheimer's disease. Task performances were compared between the groups and those found to differ significantly were entered into a logistic regression analysis.
  
  
  RESULTS
  Analyses revealed a double dissociation between nfv-PPA and lv-PPA. nfv-PPA exhibited significant emotion processing disturbance compared to lv-PPA and Controls. In contrast, only the lv-PPA group was significantly impaired on tasks of episodic memory. Logistic regression analyses showed that 87% of patients were correctly classified using emotion processing and episodic memory composite scores, together with a measure of visuospatial ability.
  
  
  CONCLUSIONS
  Non-language presenting features can help differentiate between the two non-semantic PPA syndromes, with a double dissociation observed on tasks of episodic memory and emotion processing. Based on performance on these tasks, we propose a decision tree as a complementary method to differentiate between the two non-semantic variants. These findings have important clinical implications, with identification of patients who may potentially benefit existing therapeutic interventions currently available for Alzheimer's disease.
authors.affiliation: Neuroscience Research Australia, Sydney, Australia ARC Centre of Excellence in Cognition and its Disorders, NSW, Australia School of Medical Sciences, The University of New South Wales, Sydney, Australia.
authors.forename: Olivier
authors.initials: O
authors.lastname: Piguet
authors.affiliation: Neuroscience Research Australia, Sydney, Australia ARC Centre of Excellence in Cognition and its Disorders, NSW, Australia Faculty of Health Sciences, The University of Sydney, Sydney, Australia.
authors.forename: Cristian E
authors.initials: CE
authors.lastname: Leyton
authors.affiliation: School of Medical Sciences, The University of New South Wales, Sydney, Australia.
authors.forename: Liam D
authors.initials: LD
authors.lastname: Gleeson
authors.affiliation: Neuroscience Research Australia, Sydney, Australia ARC Centre of Excellence in Cognition and its Disorders, NSW, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Hoon
authors.affiliation: Neuroscience Research Australia, Sydney, Australia ARC Centre of Excellence in Cognition and its Disorders, NSW, Australia School of Medical Sciences, The University of New South Wales, Sydney, Australia.
authors.forename: John R
authors.initials: JR
authors.lastname: Hodges
mesh_terms: D000368:Aged; D018888:Aphasia, Primary Progressive / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000523:psychology*; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D003071:Cognition; D003704:Dementia / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D003937:Diagnosis, Differential; D004644:Emotions; D005260:Female; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography
keywords: Alzheimer disease; emotions; episodic memory; frontotemporal dementia