Abstract:
Accumulation of amyloid beta (Aβ) protein in the cerebral region of the brain is one of
the hallmarks of AD and appears 15 to 20 years before the appearance of any
symptoms of AD. This prolonged asymptomatic phase of AD gives a huge potential for
the development of early detection and screening methods for AD. In addition to this,
the fact that Aβ peptide also accumulates in the retina and leads to visual impairment,
has shifted scientists' focus on the eye to be used as a diagnostic tool. Over the last
decade, the use of infrared (IR) rays to detect and study amyloid plaques has opened
new avenues in the field of neuroscience. The current study is designed to validate the
diagnosis of AD by detecting Aβ in the retina using IR rays on AlCl3-treated rodent
models. Behavioral tests were conducted to confirm symptoms of AD such as impaired
cognition and spatial learning induced in rodents, followed by mice dissection to
perform histology including H&E and Thioflavin T (ThT) staining of their retinal and
cerebral tissues for confirmation of the presence of amyloid aggregations. Rodents’
eyes were exposed to IR light for the detection of amyloid plaques by the amount of IR
radiation reflected. The presence of the plaques in the retina was confirmed by the
reflectance percentage of IR light, the more the plaques in the retina, the lower the IR
percentage reflectance as it would be absorbed by the aggregations encountered by IR
radiation. When compared to healthy mice, AD mice showed three to five times less
reflectance percentage of IR light. The findings of this study predict the utility of IR
spectroscopy in the diagnosis of AD and other neurodegenerative diseases.
