Potential Tool Diagnoses Common Vascular Dementia Contributor

A team led by the University of Southern California’s Keck School of Medicine discovered that a non-invasive eye exam could be used to screen Black Americans and other people from underdiagnosed and high-risk populations for cerebral small vessel disease, a major contributor to cognitive impairment and vascular dementia. Following Alzheimer’s disease, the second most prevalent dementia diagnosis is vascular dementia, which is related with reduced blood flow to the brain.

“Most people with cerebral small vessel disease are not diagnosed until they have significant brain damage.” The damage to brain cells is irreversible.” Xuejuan Jiang, PhD, associate professor of ophthalmology at the Keck School of Medicine and principal author of the study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, stated. “This exam might help identify those people who are at high risk of developing cerebral small vessel disease early, while they can still get help.”

The team was able to link certain characteristics in the vasculature of the eye to early indicators of cognitive loss and structural alterations often found in the brains of persons with cerebral small vessel disease by using a new type of device that looks at the blood vessels in the retina.

Innovative imaging, innovative discoveries

The research participants were all over 40 and had no history of cognitive impairment. They were recruited from the African American Eye Disease Study, a population-based study of approximately 6,000 African Americans from Inglewood, California. Participants in the study underwent a type of retinal imaging called optical coherence tomography angiography, or OCTA, at the USC Roski Eye Institute.

OCTA, a relatively new method of imaging that is rapidly being used in clinical ophthalmology practice, produces comprehensive images of tiny retinal capillaries without the requirement for a dye injection into the patient. The team was able to compute the density of these blood vessels within the retina, the amount of blood flowing through those vessels, and the speed at which the blood was traveling using these photographs. Jiang observed that OCTA can detect alterations in retinal capillaries even before patients exhibit clinical symptoms.

Participants were placed through a battery of tests to assess their cognitive performance. Some of them also had magnetic resonance imaging (MRI) of the brain, which allowed the scientists to measure the architecture of the participants’ brains. Certain early anatomical alterations in the brain have been identified as indicators of cerebral small vessel disease.

A shared link

The scientists discovered that decreased rates of blood flow through the retinal capillaries and reduced density of blood vessels are both linked to functional and anatomical abnormalities in the brain associated with cerebral small vessel disease after reviewing the data acquired during the exams.

Lower rates of blood flow and blood vessel density were linked to decreased information processing speed and executive function among study participants who undertook cognitive tests. They were also linked to three MRI parameters that have previously been linked to cerebral small vessel disease.

“This suggests that altered retinal blood flow may be a biomarker of early changes in cognition caused by cerebral small vessel disease,” said Jiang, noting that the rate of blood flow in the retinal capillaries was a more sensitive measure of changes in the brain of the two associated measures. Jiang speculated that this technique may be utilized to track illness development or the efficacy of therapy for cerebral small artery disease.

Emphasis on diversity

It is also noteworthy, according to Jiang, that the study included Black participants because Black people have historically been underrepresented in dementia research and clinical trials, despite the fact that dementia is more prevalent among Black people than white people in the United States.

According to Jiang, it is critical that studies on cerebral small vessel disease and vascular dementia include diverse participants because these conditions are more common in populations with high rates of diabetes, hypertension, and other vascular diseases, including Blacks and Latinos.

“We know how important it is for research to include more diverse patients,” Jiang said. “There needs to be more research on Blacks and Latinos because they are at higher risk, and we are hopeful that this research is moving in the direction of finding a screening and monitoring tool.”

More information : Retinal perfusion is linked to cognitive and brain MRI biomarkers in Black Americans. The Journal of the Alzheimer’s Association

https://doi.org/10.1002/alz.13469