title: Modulation of Retinal Arteriolar Central Reflection by APOE Genotype.
abstract: This study investigated the retinal arteriolar central reflex (CR, the central reflection observed in photographs of retinal vessels), which may provide information about micro-vascular health in the retina and also the brain, due to the homology between these vascular networks. The study also describes a novel computer based semi-automated technique that accurately quantifies retinal arteriolar CR and vessel width, and calculates the CR to vessel width ratio (CRR) from digital retinal photographs.
  
  
  
  Digital retinal photographs were collected from participants in the Australian Imaging, Biomarkers and Lifestyle study of ageing (AIBL), including 25 participants diagnosed with Alzheimer's disease (AD) (age 72.4 ± 7.5 yrs, 12 male, 13 female) and 123 elderly participants without dementia (cognitively normals: CN) (age 71.6 ± 5.6 yrs, 55 male, 68 female). Using a sub-cohort of 144 (22 AD, 122 CN) with the novel CRR measures, we identified significantly higher CRR levels in AD participants (mean CRR 0.253 (SD 0.04)) as compared with CN's (mean CRR 0.231 (SD 0.04), p = 0.025). Adjustment for APOE ε4 allele status however, reduced the significance (p = 0.081). CRR was significantly higher in APOE ε4 allele carriers (mean CRR 0.254 (SD 0.03) as compared with non-carriers (mean CRR 0.224 (SD 0.05), p < 0.0001).
  
  
  
  These data indicate that CRR is strongly linked to APOE ε4 status and exhibits a weaker, independent trend with AD diagnosis. The retina may be useful as a novel model for non-invasive monitoring of the effects of APOE ε4 on the central nervous system, particularly in cerebrovascular disease.
authors.affiliation: CSIRO, Private bag 5, Wembley, WA 6913. Australia.
authors.forename: Shaun
authors.initials: S
authors.lastname: Frost
authors.affiliation: CSIRO Australian e-Health Research Centre/Digital Productivity Flagship, Perth, WA. Australia.
authors.forename: Alauddin
authors.initials: A
authors.lastname: Bhuiyan
authors.affiliation: Albany Hospital, Albany. Australia.
authors.forename: David
authors.initials: D
authors.lastname: Offerman
authors.affiliation: CSIRO Australian e-Health Research Centre/Digital Productivity Flagship, Brisbane, QLD. Australia.
authors.forename: James D
authors.initials: JD
authors.lastname: Doecke
authors.affiliation: CSIRO Food and Nutrition Flagship, Parkville. Australia.
authors.forename: S Lance
authors.initials: SL
authors.lastname: Macaulay
authors.affiliation: Alzheimer's Disease Research Lab and the McCusker Alzheimer's Research Foundation, School of Medical Sciences, Edith Cowan University, Perth. Australia.
authors.forename: Hamid R
authors.initials: HR
authors.lastname: Sohrabi
authors.affiliation: National Ageing Research Institute, Melbourne. Australia.
authors.forename: David
authors.initials: D
authors.lastname: Ames
authors.affiliation: The Mental Health Research Institute, Melbourne. Australia.
authors.forename: Colin
authors.initials: C
authors.lastname: Masters
authors.affiliation: Centre of Excellence for Alzheimer's Diseases Research and Care, Sir James McCusker Alzheimer's Diseases Research Unit, Edith Cowan University Perth. Australia.
authors.forename: Ralph N
authors.initials: RN
authors.lastname: Martins
authors.affiliation: CSIRO Australian e-Health Research Centre/Digital Productivity Flagship, Perth, WA. Australia.
authors.forename: Yogesan
authors.initials: Y
authors.lastname: Kanagasingam
authors.affiliation: AIBL, Melbourne. Australia.
authors.forename: Aibl Research
authors.initials: AR
authors.lastname: Group
mesh_terms: D000368:Aged; D000375:Aging / Q000235:genetics; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology*; D053327:Apolipoprotein E4 / Q000235:genetics*; D001160:Arterioles / Q000000981:diagnostic imaging / Q000473:pathology* / Q000502:physiology / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D056726:Genetic Association Studies; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D009929:Organ Size; D010363:Pattern Recognition, Automated; D010781:Photography; D012171:Retinal Vessels / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology
chemical_list: D053327:Apolipoprotein E4
keywords: APOE; Alzheimer's; aging; diagnosis; retina; vision disorders