Retinal Amyloid Imaging for Screening Alzheimer’s Disease

Abstract

Background: Cost-effective and noninvasive methods for in vivo imaging of amyloid deposition are needed to screen Alzheimer’s disease (AD). Although retinal amyloid is a possible diagnostic marker of AD, there are very few studies on in vivo retinal amyloid imaging. Objective: To examine the usefulness of in vivo imaging of retinal amyloid in AD patients. Methods: To examine amyloid deposition, 30 Japanese subjects (10 normal control (NC), 7 with mild cognitive impairment (MCI), and 13 with AD) underwent a complete ophthalmic examination, including fundus imaging by scanning laser ophthalmoscopy before and after oral curcumin intake. Results: Retinal amyloid deposition was greater in AD than in NC subjects ( * p < 0.05) while MCI showed a slight but insignificant increase of retinal amyloid deposition relative to NC subjects. Retinal amyloid deposition was correlated with whole gray matter atrophy (r = 0.51, * p < 0.05) but not with the cognitive score of the Mini-Mental State Examination, nor with medial temporal lobe atrophy. Conclusion: The present noninvasive in vivo detection of retinal amyloid deposition is useful for screening AD patients.

No difference in retinal fluorescence after oral curcumin intake in amyloid‐proven AD cases compared to controls

“…Three previous studies showed hyperfluorescence in AD cases after curcumin intake. 7 , 8 , 9 Although these studies were of similar small sample size, AD biomarker confirmation was lacking, which is essential when relating retinal changes to AD, since other structures may cause changes in fluorescence as well. For example, retinal drusen, associated with macular degeneration, contains amyloid and other age‐related deposits.…”

No difference in retinal fluorescence after oral curcumin intake in amyloid proven AD cases compared to controls

“…More specifically related to AD pathology, three small studies reported visualization of retinal amyloid beta deposits in-vivo using curcumin, a polipotent polyphenol with fluorescent properties that binds to amyloid in post-mortem brain tissue [7][8][9]. The presence of retinal amyloid beta deposits is however not unequivocally proven, since we and other groups could not confirm amyloid beta deposits in post mortem retinal tissue [10][11][12][13][14].…”

Label-Free Hyperspectral Imaging and Deep-Learning Prediction of Retinal Amyloid β-Protein and Phosphorylated Tau

“…To increase visibility, state-of-the-art methods use exogenous fluorophores, and they have visualized retinal Aβ and pTau deposits with a high resolution. [5][6][7]15,[20][21][22][23][24][25][26][27][28] However, administrating contrast agents in humans complicates the imaging procedure, hindering its scalability for population screening. To date, only curcumin, a natural fluorochrome, has been tested and used in clinical trials to label retinal Aβ, [6,[21][22][23]25] whereas fluorophores used to visualize retinal pTau in vivo are more limited.…”

“…[5][6][7]15,[20][21][22][23][24][25][26][27][28] However, administrating contrast agents in humans complicates the imaging procedure, hindering its scalability for population screening. To date, only curcumin, a natural fluorochrome, has been tested and used in clinical trials to label retinal Aβ, [6,[21][22][23]25] whereas fluorophores used to visualize retinal pTau in vivo are more limited. Therefore, there is an unmet need to develop label-free, high-resolution imaging techniques to visualize retinal Aβ and pTau deposits for early AD screening and disease management.…”