Retinal Changes May Reflect Brain Changes in Preclinical Alzheimer’s Disease

Using Advances in Imaging

This volume loss in the retinal nerve fiber layer probably represents early demyelination or degeneration of axons, Dr. Snyder said. “This finding in the retina appears analogous, and possibly directly related, to a similar loss of white matter that is readily observable in the early stages of Alzheimer’s disease,” he said. “At the same time, patients are beginning to experience cholinergic changes in the basal forebrain and the abnormal aggregation of fibrillar beta-amyloid plaques. I do not know to what extent these changes are mechanistically dependent on each other, but they appear to also be happening, in the earliest stages of the disease course, in the retina.”

More research is needed before retinal scanning can be employed as a risk-assessment tool, however. “Every time we have a major advance in imaging, the technical engineering breakthroughs precede our detailed understanding of what we are looking at and what to measure,” Dr. Snyder said. “This is where we are right now with retinal imaging. Biologically, it makes sense to be looking at this as a marker of risk in those who are clinically healthy, and maybe later as a marker of disease progression. But there is a lot of work to be done here yet.”

Dr. Snyder’s project was supported by a research award from Pfizer and a grant from Avid Radiopharmaceuticals.

—Michele G. Sullivan