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Non-invasive eye exam may detect early signs of cognitive decline

A research team, led by the Keck School of Medicine at USC, has made a groundbreaking discovery regarding the potential use of a non-invasive eye examination for screening high-risk populations, including Black Americans, for cerebral small vessel disease. This disease significantly contributes to cognitive impairment and dementia, making it the second most common dementia diagnosis after Alzheimer's disease.

According to Dr. Xuejuan Jiang, an associate professor of ophthalmology at the Keck School of Medicine and the study's lead author, most individuals with cerebral small vessel disease remain undiagnosed until substantial brain damage has already occurred. Unfortunately, this brain damage is irreversible. However, this eye examination could serve as a crucial tool in identifying individuals at high risk of developing cerebral small vessel disease at an early stage when intervention is still possible.

The research team utilized an innovative device designed to examine the blood vessels in the retina. With this device, they successfully linked specific characteristics in the eye's vasculature to early indicators of cognitive decline and structural changes often observed in the brains of those with cerebral small vessel disease. This discovery has the potential to revolutionize early detection and intervention for this debilitating condition.

New imaging, new insights

The study's participants were drawn from the African American Eye Disease Study, a population-based research initiative encompassing over 6,000 African Americans residing in Inglewood, California. All individuals included in the study were aged 40 or above and exhibited no prior history of cognitive impairment. To gain insights into their retinal health, these participants underwent a specialized retinal imaging technique known as optical coherence tomography angiography (OCTA), conducted at the USC Roski Eye Institute.

OCTA, a relatively recent advancement in ophthalmological imaging, enables the capture of intricate images of minuscule retinal capillaries without the need for invasive dye injections. Using these high-resolution images, the research team calculated parameters such as the density of these retinal blood vessels, the volume of blood coursing through them, and the speed of blood flow. Dr. Jiang emphasized that OCTA can detect changes in retinal capillaries before patients exhibit clinical symptoms.

The participants also underwent a battery of cognitive function assessments. A subset of them additionally underwent magnetic resonance imaging (MRI) scans of their brains. These MRI scans allowed the research team to measure structural changes within the participants' brains, some of which are recognized as early biomarkers of cerebral small vessel disease. This multifaceted approach provided valuable insights into the connections between retinal health, cognitive function, and structural brain changes.

A common connection

Upon scrutinizing the data derived from the examinations, the research team uncovered compelling connections between diminished blood flow rates within the retinal capillaries and reduced density of blood vessels with both functional and structural alterations in the brain associated with cerebral small vessel disease.

Among individuals who underwent cognitive assessments within the study, those with lower rates of blood flow and reduced blood vessel density exhibited poorer information processing speed and executive function. Furthermore, these findings were correlated with three specific MRI measurements known to be indicative of cerebral small vessel disease.

Dr. Jiang emphasized the significance of these results, suggesting that altered retinal blood flow may serve as a biomarker for early cognitive changes linked to cerebral small vessel disease. Notably, among the associated measures, the rate of blood flow in retinal capillaries emerged as a particularly sensitive indicator of brain changes. Jiang also highlighted the potential utility of this technology in tracking disease progression and assessing the effectiveness of treatments for cerebral small vessel disease.

Focus on diversity

Dr. Jiang also underscored the significance of conducting this study with a predominantly Black participant group. Historically, Black individuals have not been adequately represented in research and clinical trials related to dementia and Alzheimer's disease, despite the fact that dementia is more prevalent among Black Americans than among their white counterparts in the United States.

Dr. Jiang stressed the crucial importance of ensuring diversity in studies focusing on cerebral small vessel disease and vascular dementia. These conditions are more prevalent among populations with elevated rates of diabetes, hypertension, and other vascular diseases, which includes Black and Latino communities.

She emphasized, “We understand the vital need for research to encompass a broader spectrum of patients. In order to address the higher risks faced by Black and Latino individuals, we must encourage and foster more research in these communities. Our hope is that this research will pave the way for the development of effective screening and monitoring tools.” This approach aims to bridge longstanding disparities in healthcare research and provide tailored solutions for at-risk populations.

Source: Keck School of Medicine of USC


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