Imaging Retinal Amyloid The Virtual Brain Biopsy

Abstract

Alzheimer’s Disease (AD) is mostly regarded as Alzheimer’s disease dementia. AD is diagnosed with certitude at autopsy or via brain biopsy. However, it is now known that the AD pathological abnormalities, detected in vivo by biological markers, precede the clinical symptoms by years or even decades. The uniform lack of success in treating AD may be due to the fact that therapeutic intervention is begun too late in the course of the disease. The earliest recognizable pathological event in AD is aggregated cerebral amyloid-β deposition; this pathology may be present 20 years before the onset of dementia. A newly developed retinal camera visualizes amyloid in the retina and, through computer analysis, quantifies it yielding a number: the retinal amyloid index. The retina is an extension of the brain and early studies show that the amyloid deposition in the retinal correlates with cerebral amyloid deposition. This article introduces this imaging technology and suggests a role for early detection of the pathology associated with AD. Moreover, the utility of this technology in monitoring interventional trials is suggested. If the sensitivity and specificity of this imaging of retinal amyloid is successful enough to be embraced by the research community, it may ultimately be considered a “virtual brain biopsy.