title: Retinal microvascular network attenuation in Alzheimer's disease.
abstract: BACKGROUND
  Cerebral small-vessel disease has been implicated in the development of Alzheimer's disease (AD). The retinal microvasculature enables the noninvasive visualization and evaluation of the systemic microcirculation. We evaluated retinal microvascular parameters in a case-control study of AD patients and cognitively normal controls.
  
  
  METHODS
  Retinal images were computationally analyzed and quantitative retinal parameters (caliber, fractal dimension, tortuosity, and bifurcation) measured. Regression models were used to compute odds ratios (OR) and confidence intervals (CI) for AD with adjustment for confounders.
  
  
  RESULTS
  Retinal images were available in 213 AD participants and 294 cognitively normal controls. Persons with lower venular fractal dimension (OR per standard deviation [SD] increase, 0.77 [CI: 0.62-0.97]) and lower arteriolar tortuosity (OR per SD increase, 0.78 [CI: 0.63-0.97]) were more likely to have AD after appropriate adjustment.
  
  
  CONCLUSIONS
  Patients with AD have a sparser retinal microvascular network and retinal microvascular variation may represent similar pathophysiological events within the cerebral microvasculature of patients with AD.
authors.affiliation: Centre for Medical Education, Queen's University Belfast, Belfast, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Williams
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: McGowan
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Chris R
authors.initials: CR
authors.lastname: Cardwell
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore ; Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Graduate Medical School, National University of Singapore, Singapore, Singapore.
authors.forename: Carol Y
authors.initials: CY
authors.lastname: Cheung
authors.affiliation: Southern Health and Social Care Trust, Craigavon Hospital, Craigavon, UK.
authors.forename: David
authors.initials: D
authors.lastname: Craig
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Passmore
authors.affiliation: Centre for Experimental Medicine, Queen's University Belfast, Belfast, UK.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Silvestri
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Maxwell
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, UK.
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: McKay
keywords: Alzheimer's disease; Microcirculation; Retina; Retinal vasculature; Small-vessel disease