Relationship of Area of Soft Drusen in Retina with Cerebral Amyloid-β Accumulation and Blood Amyloid-β Level in the Elderly

Background: Histopathological studies have confirmed that soft drusen contains amyloid-beta (A beta). Objective: To examine the relationship between the area of soft drusen in the macular area and cerebral A beta accumulation or plasma A beta level in elderly persons without dementia. Methods: Fourteen consecutive patients (18 eyes) aged >= 50 years with macular soft drusen were studied prospectively. From color fundus photographs, the area of soft drusen (pixel) within a 6,000 mu m diameter with the macula as center was measured. Standard uptake value ratio (SUVR) was obtained from positron emission tomography using florbetapir, which indicates the ratio of cerebral cortical-to-cerebellar A beta accumulation. Ratio of plasma A beta(1-42) to A beta(1-40) level was calculated. Results: Mean age was 73.3 +/- 7.6 years. The soft drusen area was 4.32 +/- 2.42 mm(2). The SUVR was 1.08 +/- 0.15. Plasma A beta(1-42)/A beta(1-40) ratio was 0.17 +/- 0.08. When SUVR >= 1.10 was defined as positive and < 1.10 as negative, the soft drusen area in SUVR-positive patients (6.19 +/- 1.14 mm(2)) was significantly (p = 0.0043) larger than that in SUVR-negative patients (3.13 +/- 2.27 mm(2)). Multivariate regression analysis showed that SUVR positivity correlated with soft drusen area (p = 0.0484) and with Voxel-based Specific Regional Analysis System for Alzheimer's Disease score (p = 0.0360). However, there was no correlation with gender (p = 0.1921), age (p = 0.2361), Alzheimer's Disease Assessment Scale score (p = 0.6310), Mini-Mental State Examination score (p = 0.4246), or plasma A beta(1-42)/A beta(1-40) ratio (p = 0.8398). Conclusion: Among elderly persons without dementia, the area of soft drusen was larger in those with more extensive cerebral A beta accumulation. The area of soft drusen may be a biomarker of cerebral A beta accumulation.