title: Differentiating between visual hallucination-free dementia with Lewy bodies and corticobasal syndrome on the basis of neuropsychology and perfusion single-photon emission computed tomography.
abstract: BACKGROUND
  Dementia with Lewy bodies (DLB) and Corticobasal Syndrome (CBS) are atypical parkinsonian disorders with fronto-subcortical and posterior cognitive dysfunction as common features. While visual hallucinations are a good predictor of Lewy body pathology and are rare in CBS, they are not exhibited in all cases of DLB. Given the clinical overlap between these disorders, neuropsychological and imaging markers may aid in distinguishing these entities.
  
  
  METHODS
  Prospectively recruited case-control cohorts of CBS (n =31) and visual hallucination-free DLB (n =30), completed neuropsychological and neuropsychiatric measures as well as brain perfusion single-photon emission computed tomography and structural magnetic resonance imaging (MRI). Perfusion data were available for forty-two controls. Behavioural, perfusion, and cortical volume and thickness measures were compared between the groups to identify features that serve to differentiate them.
  
  
  RESULTS
  The Lewy body with no hallucinations group performed more poorly on measures of episodic memory compared to the corticobasal group, including the delayed and cued recall portions of the California Verbal Learning Test (F (1, 42) =23.1, P <0.001 and F (1, 42) =14.0, P =0.001 respectively) and the delayed visual reproduction of the Wechsler Memory Scale-Revised (F (1, 36) =9.7, P =0.004). The Lewy body group also demonstrated reduced perfusion in the left occipital pole compared to the corticobasal group (F (1,57) =7.4, P =0.009). At autopsy, the Lewy body cases all demonstrated mixed dementia with Lewy bodies, Alzheimer's disease and small vessel arteriosclerosis, while the corticobasal cases demonstrated classical corticobasal degeneration in five, dementia with agyrophilic grains + corticobasal degeneration + cerebral amyloid angiopathy in one, Progressive Supranuclear Palsy in two, and Frontotemporal Lobar Degeneration-Ubiquitin/TAR DNA-binding protein 43 proteinopathy in one. MRI measures were not significantly different between the patient groups.
  
  
  CONCLUSIONS
  Reduced perfusion in the left occipital region and worse episodic memory performance may help to distinguish between DLB cases who have never manifested with visual hallucinations and CBS at earlier stages of the disease. Development of reliable neuropsychological and imaging markers that improve diagnostic accuracy will become increasingly important as disease modifying therapies become available.
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Misch
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Mitchell
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Francis
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Kayla
authors.initials: K
authors.lastname: Sherborn
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Katayoun
authors.initials: K
authors.lastname: Meradje
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Alicia A
authors.initials: AA
authors.lastname: McNeely
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Kie
authors.initials: K
authors.lastname: Honjo
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Jiali
authors.initials: J
authors.lastname: Zhao
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Christopher Jm
authors.initials: CJ
authors.lastname: Scott
authors.affiliation: Department of Medical Biophysics, Sunnybrook Health Sciences Centre, University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Curtis B
authors.initials: CB
authors.lastname: Caldwell
authors.affiliation: Department of Nuclear Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Ehrlich
authors.affiliation: Neuropsychology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Prathiba
authors.initials: P
authors.lastname: Shammi
authors.affiliation: Department of Medical Biophysics, Sunnybrook Health Sciences Centre, University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: MacIntosh
authors.affiliation: Department of Pathology, Sunnybrook Health Sciences Centre, University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Bilbao
authors.affiliation: Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital, University Health Network, Toronto, Canada.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Lang
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada ; Department of Medicine (Neurology), Brain Sciences Research Program, Sunnybrook Health Sciences, Centre University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Black
authors.affiliation: L.C. Campbell Cognitive Neurology Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada ; Department of Medicine (Neurology), Brain Sciences Research Program, Sunnybrook Health Sciences, Centre University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada ; Cognition & Movement Disorders Clinic, Sunnybrook Health Sciences Centre, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada ; Neurogenetics Section, Centre for Addiction and Mental Health, University of Toronto, Room A4 42, 2075 Bayview Avenue, Toronto, ON M4N 3M5 Canada.
authors.forename: Mario
authors.initials: M
authors.lastname: Masellis