Biomarkers Indicative of Late Stage Alzheimer’s Disease Found in the Brain and Retina

Abstract

PurposeAlzheimer’s Disease (AD) is a common neurological disorder affecting millionsof individuals worldwide, and therefore identification of retinal biomarkersfor a noninvasive diagnosis of the disease is critical to confirm the presence of this brain disorder.MethodsCryosections of brains and retinas from cadavers were analyzed. The structures of the brain specifically focused on were the prefrontal cortex (PFC), hippocampus, temporal lobe, visual cortex. Each tissue section was immunostained with antibodies against total tau (TT), phospho‐tau 181 (PT181), phospho‐tau 205 (PT205), and beta‐amyloid (BA). Every stained section was then microscopically analyzed to compare and contrast each marker using optical density (OD) measurements.Results2 cadavers without a history of neurodegenerative disease (1 male, 1 female) and 4 cadavers affected by AD (2 males, 2 females) were used. Retina samples of AD cadavers expressed a statistical significance increase in OD of the TT marker when compared to normal cadavers (AD = 0.37 OD ± 0.179, Normal = 0.01 OD ± 0.0049). In regards to the brain structures, only the TT markers in PFC were found to have statistical significant increases in OD value (AD = 0.28 OD ± 0.0621, Normal = 0.04 OD ± 0.0423). TT, PT181, PT205, and BA also expressed slight increases in OD in several brain structures of the AD cadavers but were not found to be statistically significant.ConclusionThere is a significant increase in the TT marker in the retina with similar findings in the PFC. This suggests that using TT as a marker in the PFC and retina has the highest potential to aid in diagnosing AD, with a possibility of studying the progression of AD through TT in different areas of the brain in future research.