Retinal Functional Changes in Early Alzheimer’s Disease: A Multimodal Electroretinography Study
Abstract (summary)
Alzheimer’s disease (AD) is increasingly recognized as a disorder of early synaptic dysfunction, which may extend beyond the central nervous system to the retina. Retinal electrophysiology provides a non-invasive approach to assessing neuronal function within well-characterized visual pathways. This study aimed to investigate retinal function in cognitively normal and cognitively impaired individuals using multimodal electroretinography, with particular focus on the rod pathway, the first visual synapse, and retinal ganglion cell activity.
Full-field electroretinography (ffERG), photopic negative response (PhNR), and pattern electroretinography (PERG) were recorded in all participants. Scotopic ffERG responses were used to assess rod pathway function, while PhNR and PERG were used to evaluate inner retinal and ganglion cell function. PERG analysis focused on the P50 and N95 components of the ISCEV-standard condition, and an experimental 13-step PERG protocol varying check size and contrast was additionally explored.
Cognitively impaired participants demonstrated reduced dim-flash scotopic b-wave amplitudes, suggesting dysfunction at the rod–bipolar synapse. PhNR amplitudes were reduced, consistent with impaired retinal ganglion cell function. PERG analysis revealed a reduction in P50 amplitude. N95 implicit time demonstrated a trend toward prolongation. Exploration of an extended PERG protocol revealed contrast-dependent variation in group differences, with the most consistent patterns observed in N95 implicit time. These findings indicate functional alterations in both outer and inner retinal pathways in individuals with cognitive impairment due to AD. Retinal electrophysiology may provide a valuable non-invasive window into early synaptic dysfunction in Alzheimer’s disease, with potential applications in understanding disease mechanisms.
Indexing (details)
Neurosciences;
Pathology;
Medical imaging
0574: Medical imaging
0317: Neurosciences
0571: Pathology
