title: Orthostatic hypotension, cerebral hypoperfusion, and visuospatial deficits in Lewy body disorders.
abstract: BACKGROUND
  Orthostatic hypotension and cognitive impairment are two non-motor attributes of Lewy body spectrum disorders that impact independence. This proof-of-concept study examined cerebral blood flow (perfusion) as a mediator of orthostatic hypotension and cognition.
  
  
  METHODS
  In fifteen patients with Lewy body disorders, we estimated regional perfusion using pseudo-continuous arterial spin labeling MRI, and quantified orthostatic hypotension from the change in systolic blood pressure between supine and standing positions. Executive, visuospatial, attention, memory, and language domains were characterized by neuropsychological tests. A matching sample of non-demented adults with cerebral small vessel disease was obtained to contrast perfusion patterns associated with comorbid vascular pathology.
  
  
  RESULTS
  Compared to the vascular group, patients with Lewy body disorders exhibited lower perfusion to temporal and occipital lobes than to frontal and parietal lobes (q < 0.05). A greater orthostatic drop in systolic pressure was associated with lower occipito-parietal perfusion in these patients (uncorrected p < 0.005; cluster size ≥ 20 voxels). Although orthostatic hypotension and supine hypertension were strongly correlated (r = -0.79, p < 0.001), the patterns of association for each with perfusion were distinct. Specifically, supine hypertension was associated with high perfusion to anterior and middle cerebral arterial territories, as well as with low perfusion to posterior regions. Perfusion within orthostatic hypotension-defined regions was directly related to performance on visuospatial and attention tasks, independent of dementia severity (p < 0.05).
  
  
  CONCLUSIONS
  These findings provide new insight that regional cerebral hypoperfusion is related to orthostatic hypotension, and may be involved in domain-specific cognitive deficits in Lewy body disorders.
authors.affiliation: Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Robertson
authors.affiliation: Cognitive & Movement Disorders Clinic, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Messner
authors.affiliation: Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Shirzadi
authors.affiliation: Neurology, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada.
authors.forename: Galit
authors.initials: G
authors.lastname: Kleiner-Fisman
authors.affiliation: Elder Care Program, North York General Hospital, Toronto, Ontario, Canada.
authors.forename: Joyce
authors.initials: J
authors.lastname: Lee
authors.affiliation: Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada; Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Julia
authors.initials: J
authors.lastname: Hopyan
authors.affiliation: Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada; Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Lang
authors.affiliation: Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada; Cognitive & Movement Disorders Clinic, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; L.C. Campbell Cognitive Neurology Research Unit, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Black
authors.affiliation: Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: MacIntosh
authors.affiliation: Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada; Cognitive & Movement Disorders Clinic, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; L.C. Campbell Cognitive Neurology Research Unit, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada. Electronic address: mario.masellis@sunnybrook.ca.
authors.forename: Mario
authors.initials: M
authors.lastname: Masellis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply* / Q000473:pathology; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D060825:Cognitive Dysfunction / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D015331:Cohort Studies; D003704:Dementia / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D066128:Gray Matter / Q000473:pathology; D006179:Gyrus Cinguli / Q000098:blood supply / Q000473:pathology; D006801:Humans; D007024:Hypotension, Orthostatic / Q000503:physiopathology* / Q000523:psychology; D020961:Lewy Body Disease / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000098:blood supply / Q000473:pathology; D009929:Organ Size; D010296:Parietal Lobe / Q000098:blood supply / Q000473:pathology; D010300:Parkinson Disease / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D011446:Prospective Studies; D066127:White Matter / Q000473:pathology
keywords: Cerebral blood flow; Orthostatic hypotension; Parkinson's disease; Supine hypertension; Visuospatial