Retinal biomarkers useful in detecting early AD abnormalities
Retinal biomarkers assisted with early detection of in vivo Alzheimer’s disease abnormalities in adults, according to a study published in JAMA Ophthalmology.
“The findings showed patterns of association between each AD pathologic characteristic and measurement values of the retina in cognitively normal older adults, indicating that cerebral [amyloid-beta] deposition and AD neurodegeneration may have differential association with specific changes of the retina,” Min Soo Byun, MD, PhD, of the department of neuropsychiatry at Seoul National University Bundang Hospital, and colleagues wrote.
Byun and colleagues investigated the association between structural and functional alterations of the retina with in vivo AD characteristics. The cross-sectional study included 49 participants who tested as cognitively normal. The cohort was split evenly by sex and had a mean age of 70.6 years. They underwent a complete ophthalmic examination with multifocal electroretinogram and amyloid-beta positron emission tomography and MRI at the Seoul National University Hospital.
Byun and colleagues compared participants with amyloid-beta deposition (n = 16) with those without (n = 33). The participants with amyloid-beta exhibited reduced inner nasal macular thickness and retinal nerve fiber layer thickness. In addition, they showed higher implicit time in rings 2 to 6 compared with the other group regarding functional parameters of the retina. The researchers discovered the ganglion cell complex–inner plexiform layer thickness correlated with AD–related neurodegeneration in the study population.
The findings were limited by the small study size and an inability to determine the relationship between retinal alternations and in vivo AD abnormalities using a cross-sectional design, according to the researchers.
“A screening model based on these results showed 90% diagnostic accuracy to detect [amyloid-beta] deposition in these cognitively normal individuals,” Byun and colleagues wrote. They added, “Our finding suggests that delayed implicit time is a potential sensitive indicator of early retinal neuronal change related to cerebral [amyloid-beta] deposition.”
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As often described in literature, “Eyes are a window to the body.” This cross-sectional study suggests they are a window to the brain. Byun and colleagues addressed a correlation between biomarkers obtained from swept-source OCT and amyloid-beta deposition in the brain — precursor lesions of AD. The study suggested that OCT can potentially play a significant role in screening for early detection of AD.
This is not the first study of its kind that connects the cerebrum and the fundus, and it won’t be the last. Clinical scientists have tried to use the fundus as an indicator for neurological conditions, such as multiple sclerosis, Parkinson’s disease and traumatic brain injuries. Indeed, many of those studies also have shown correlations with its disease activities and OCT abnormalities. Thus, eye care practitioners are cautioned against casually suggesting a risk for AD and dementia when seeing abnormal OCT findings in patients with otherwise healthy-appearing eyes. However, this study adds another milestone to help close the loop between the cerebrum and the eye.
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