Study: Correlation found between vitreous human biomarkers and Alzheimer’s disease

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Researchers from Boston Medical Center have discovered a correlation between biomarkers in the vitreous humor of the eye and pathologically confirmed cases of Alzheimer’s disease (AD) and chronic traumatic encephalopathy (CTE) in post-mortem brain and eye tissue.

According to a study in IOS Press,¹ this exploratory study indicates that biomarkers in the vitreous humor may serve as a proxy for neuropathological disease.

Boston Medical Center noted in the news release the incidence of dementias like AD continues to increase, and as of 2021, 6.2 million North Americans above 65 years of age are suffering from AD, and this number is projected to reach 13.2 million by 2060.

According to the news release, the diagnosis of both AD and CTE is based on symptoms, clinical exam findings, and cognitive testing, but the diagnoses are not confirmed until post-mortem examination of the brain. In Alzheimer’s disease, neuropathological changes occur decades before symptom onset, so by the time a patient is diagnosed, the therapeutic effect is often limited. Studying biomarkers that may predict disease and can be measured before symptoms develop is a significant priority in AD research.

Patients with eye disease have an increased risk for developing neurodegenerative disease, and several studies have established a link between neurodegenerative diseases and ophthalmic conditions like glaucoma, diabetic retinopathy, age-related macular degeneration, and cataracts, Boston Medical Center noted in its news release. Patients with these eye conditions are known to have an increased risk of developing AD, so investigating biomarkers in this at-risk population is important in order to study their role in early diagnosis.

Manju Subramanian, MD, an ophthalmologist at Boston Medical Center and an associate professor in ophthalmology at Boston University Chobanian & Avedisian School of Medicine, noted to the knowledge of researchers, this is the first study to investigate the role of vitreous fluid biomarkers and link it to confirmed post-mortem brain tissue pathological examination of AD.

“In addition, this is the first study to find a link between vitreous fluid biomarkers and confirmed CTE,” Subramanian said. “Our findings provide further evidence to support the potential role of vitreous biomarkers in early diagnosis and prognostication of diseases like AD and CTE.”

The medical center noted in its news release the researchers discovered a link of biomarkers, including total Tau and neurofilament light-chain (NfL) with pathologically confirmed AD and CTE. They noted the alterations of these neurodegenerative proteins in the vitreous fluid confirm that the eye reflects neuropathological changes in the brain and further supports investigations into the eye’s potential role in the diagnosis of these diseases.1

According to researchers, their findings build on earlier efforts that biomarkers in vitreous fluid are linked to cognitive function in live patients with both normal cognition and mild cognitive impairment. These findings are also foundational for future studies to continue to investigate the role of biomarkers and other eye fluid in the diagnosis, prognostication, and management of diseases such as AD and CTE, according to the news release.

Reference:

1. Vig, Viha et al. ‘Vitreous Humor Biomarkers Reflect Pathological Changes in the Brain for Alzheimer’s Disease and Chronic Traumatic Encephalopathy’. 1 Jan. 2023 : 1181 – 1193.