Filling in the Gaps

Is retinal capillary perfusion a biomarker of cerebral small vessel disease and impaired cognition in those at higher risk of dementia? A research team from the University of Southern California (USC) Keck School of Medicine enrolled 96 Black Americans – without known cognitive impairment – and found that “lower retinal capillary perfusion is associated with worse information processing, fluid cognition, and MRI biomarkers of cerebral small vessel disease” (1).

Here, Xuejuan Jiang, an assistant professor at USC and co-author on the paper tells us more.

Could you please explain the aim and approach of the study?
 

Cerebral small vessel disease plays a significant role in the development of dementia. Unfortunately, most individuals with this condition remain undiagnosed until substantial brain damage has already occurred. Therefore, we embarked on an investigation to identify imaging measures that could serve as invaluable tools for the early detection and ongoing monitoring of cerebral small vessel diseases and their association with dementia.

Recognizing the striking similarities between the retina and the brain, we postulated that alterations in retinal capillary perfusion could serve as early biomarkers for cerebral small vessel disease and its impact on cognitive function. To put our hypothesis to the test, we used optical coherence tomography angiography (OCT-A) – a noninvasive, high-resolution imaging technology – to examine retinal capillaries in a cohort of older African-American individuals. In addition to this retinal examination, we conducted cognitive assessments and obtained MRI scans. Our findings unveiled a notable correlation: diminished retinal perfusion was associated with poorer cognitive performance and more pronounced changes in brain structure.

How could your findings improve therapeutic options for Black American patients?
 

Our results underscore the potential of retinal imaging to screen individuals at high risk of cerebral small vessel disease, enabling early intervention. Retinal imaging may also facilitate the monitoring of disease progression or regression in response to treatments.

In the paper, you note that Black Americans are an understudied group. What can be done to increase representation in future studies?
 

Our commitment to advancing this research extends to the imperative need for inclusivity. We emphasize the urgency of conducting further studies among underrepresented groups in dementia research, particularly among African Americans, Asian Americans, and immigrant populations, who may be at higher risk for dementia or have difficulty accessing dementia care.  It is crucial that we allocate more resources and investment into health research among these understudied populations.

Furthermore, there is a pressing need for health education programs tailored to the unique needs of these diverse groups to enhance awareness and understanding of dementia. By increasing support for research and education, we can work towards more equitable dementia care and prevention.

How do you plan to build on this study?
 

Despite the promising findings of our investigation, further research is essential. To solidify our findings, we must validate them in diverse populations, gather longitudinal data to ascertain the predictive value of retinal imaging, delve into cognitive and brain structural assessments in greater depth, and explore factors that may influence this intriguing connection between the eye and the brain.